From Newsgroup: rec.games.pinball

Long story....

Punchline is that the zener labelled as VR1 in the original board caught
fire.

Two of us were called into the pinball museum to rescue a Bally Paragon.

Another person tried to 'upgrade' the rectifier board to a new after-
market one. We were told the voltages were 'wrong' after the upgrade.

We found that the HV was low and the solenoid V was ~ 100 V.

A quick look and it appeared that a pair of wires off the transformer
from the HV and the solenoid AC were switched. We didn't see any
damage, but there was a smell that bothered us. Maybe the transformer?

So we rewired the board correctly from the transformer. Double-checked everything.

Wanted to check the AC coming out of the transformer. Removed fuses F1
- F5.

Turned it on. The zener in the VR1 location burned up and caught fire.

I have not figured out how voltage could have gotten to VR1 with the
fuses removed.

Any suggestions on where to go from here?

Maybe if multiple bridges were shorted. If BR3, ground to AC on the
fuse was shorted, and the HV diode from ground to AC was shorted.

We removed BR3 and replaced it because it seemed to test shorted. But
the removed bridge tested fine in the diode test.

This after-market board has a small bridge in place of the HV 1N4004
diodes in the original.
--
http://orcalcoast.com/
--- Synchronet 3.18c-Win32 NewsLink 1.113

From Newsgroup: rec.games.pinball

On 2021/05/26 12:29 p.m., LexingtonVAPin wrote:

Long story....

Punchline is that the zener labelled as VR1 in the original board caught fire.

Two of us were called into the pinball museum to rescue a Bally Paragon.

Another person tried to 'upgrade' the rectifier board to a new after-
market one.  We were told the voltages were 'wrong' after the upgrade.

We found that the HV was low and the solenoid V was ~ 100 V.

A quick look and it appeared that a pair of wires off the transformer
from the HV and the solenoid AC were switched.  We didn't see any > damage, but there was a smell that bothered us.  Maybe the transformer?

So we rewired the board correctly from the transformer.  Double-checked everything.

Wanted to check the AC coming out of the transformer.  Removed fuses F1
- F5.

Turned it on.  The zener in the VR1 location burned up and caught fire.

VR1 is NOT a zener, it is supposed to be a MOV and it is also supposed
to be after fuse F4.

I have not figured out how voltage could have gotten to VR1 with the
fuses removed.

Either you or the board designer made a mistake, or you missed something the previous 'tech' did. Can you get the aftermarket board's
installation instructions?

Any suggestions on where to go from here?

I highly recommend Pinhead's Bally/Stern rectifier board that we sell
(here in BC) and you might be able to get from Player 1 or perhaps
Toronto Pinball (Hamilton) of The Church Of The Silver Ball in
Missisagua (I think).
Ours is here and you can download the manual which gives you all the
wiring info which may apply to your rectifier board IF the designer
followed Bally/Stern labeling. https://flippers.com/catalog_oc/bally-stern-replacement-rectifier-board-p-2678.html?search=pinhead

Maybe if multiple bridges were shorted.  If BR3, ground to AC on the
fuse was shorted, and the HV diode from ground to AC was shorted.

We removed BR3 and replaced it because it seemed to test shorted. 

But

the removed bridge tested fine in the diode test.

Wiring problems...

This after-market board has a small bridge in place of the HV 1N4004
diodes in the original.

That shouldn't matter IF it is rated at a high enough breakdown voltage.
John :-#)#
--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
--- Synchronet 3.18c-Win32 NewsLink 1.113

From Newsgroup: rec.games.pinball

The MOV is rated at 45 to 50 volts, so it did it's job!
it saw the 100v and FRIED, which is *exactly*
what it is supposed to do! This forces a fuse implosion,
which is what you want too. But when a MOV goes,
it GOES HARD AND VIOLENT. but that's what it's
supposed to do. it was preventing over voltage to
the coils in the game. Nothing else should have
fried, as the 43 volt coil power is unregulated, and
the bridge should be able to handle the 100v you
gave it.

You can run without the MOV, but probably a good
idea to install a new one!

Also when i do a rectifier (transformer) board replacement,
after I'm done, you should *always* *always* *always* hook
the input connector up to 120 volts and test *all* the voltages.
Look at the schematics to get the exact two pins on the
input power connector. Frankly this takes all of about 1 minute
to do. All you need is two alligator clips on the rectifier board
connector 120vac pins. Or use the game's input plug (don't
attach the other two connectors.) And then use the test points
to check the voltages (6vdc, 240vdc, 15vdc, 6vac, 43vdc.)
If you had done that, problems would have been avoided...
(though that MOV would have still blown up!)


On Wednesday, May 26, 2021 at 5:26:01 PM UTC-4, John Robertson wrote:

On 2021/05/26 12:29 p.m., LexingtonVAPin wrote:

Long story....

Punchline is that the zener labelled as VR1 in the original board caught fire.

Two of us were called into the pinball museum to rescue a Bally Paragon.

Another person tried to 'upgrade' the rectifier board to a new after- market one. We were told the voltages were 'wrong' after the upgrade.

We found that the HV was low and the solenoid V was ~ 100 V.

A quick look and it appeared that a pair of wires off the transformer
from the HV and the solenoid AC were switched. We didn't see any
damage, but there was a smell that bothered us. Maybe the transformer?

So we rewired the board correctly from the transformer. Double-checked everything.

Wanted to check the AC coming out of the transformer. Removed fuses F1
- F5.

Turned it on. The zener in the VR1 location burned up and caught fire.

VR1 is NOT a zener, it is supposed to be a MOV and it is also supposed
to be after fuse F4.

I have not figured out how voltage could have gotten to VR1 with the
fuses removed.

Either you or the board designer made a mistake, or you missed something
the previous 'tech' did. Can you get the aftermarket board's
installation instructions?

Any suggestions on where to go from here?

I highly recommend Pinhead's Bally/Stern rectifier board that we sell
(here in BC) and you might be able to get from Player 1 or perhaps
Toronto Pinball (Hamilton) of The Church Of The Silver Ball in
Missisagua (I think).
Ours is here and you can download the manual which gives you all the
wiring info which may apply to your rectifier board IF the designer
followed Bally/Stern labeling.

https://flippers.com/catalog_oc/bally-stern-replacement-rectifier-board-p-2678.html?search=pinhead

Maybe if multiple bridges were shorted. If BR3, ground to AC on the
fuse was shorted, and the HV diode from ground to AC was shorted.

We removed BR3 and replaced it because it seemed to test shorted.

But

the removed bridge tested fine in the diode test.

Wiring problems...

This after-market board has a small bridge in place of the HV 1N4004 diodes in the original.

That shouldn't matter IF it is rated at a high enough breakdown voltage.

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

--- Synchronet 3.18c-Win32 NewsLink 1.113

From Newsgroup: rec.games.pinball

On 2021/05/26 3:00 p.m., cfhatprovidedotnet wrote:

The MOV is rated at 45 to 50 volts, so it did it's job!
it saw the 100v and FRIED, which is *exactly*
what it is supposed to do! This forces a fuse implosion,
which is what you want too. But when a MOV goes,
it GOES HARD AND VIOLENT. but that's what it's
supposed to do. it was preventing over voltage to
the coils in the game. Nothing else should have
fried, as the 43 volt coil power is unregulated, and
the bridge should be able to handle the 100v you
gave it.

They had ALL the fuses out. Nothing should have happened...

If the MOV blew because it was connected to the 230VAC, that would have destroyed the transformer - that winding can't handle more than about
500MA after all.

It might be the MOV is somehow hooked up to the line voltage...

John :-#)#

You can run without the MOV, but probably a good
idea to install a new one!

Also when i do a rectifier (transformer) board replacement,
after I'm done, you should *always* *always* *always* hook
the input connector up to 120 volts and test *all* the voltages.
Look at the schematics to get the exact two pins on the
input power connector. Frankly this takes all of about 1 minute
to do. All you need is two alligator clips on the rectifier board
connector 120vac pins. Or use the game's input plug (don't
attach the other two connectors.) And then use the test points
to check the voltages (6vdc, 240vdc, 15vdc, 6vac, 43vdc.)
If you had done that, problems would have been avoided...
(though that MOV would have still blown up!)

On Wednesday, May 26, 2021 at 5:26:01 PM UTC-4, John Robertson wrote:

On 2021/05/26 12:29 p.m., LexingtonVAPin wrote:

Long story....

Punchline is that the zener labelled as VR1 in the original board caught >>> fire.

Two of us were called into the pinball museum to rescue a Bally Paragon. >>>
Another person tried to 'upgrade' the rectifier board to a new after-
market one. We were told the voltages were 'wrong' after the upgrade.

We found that the HV was low and the solenoid V was ~ 100 V.

A quick look and it appeared that a pair of wires off the transformer
from the HV and the solenoid AC were switched. We didn't see any
damage, but there was a smell that bothered us. Maybe the transformer?

So we rewired the board correctly from the transformer. Double-checked
everything.

Wanted to check the AC coming out of the transformer. Removed fuses F1
- F5.

Turned it on. The zener in the VR1 location burned up and caught fire.

VR1 is NOT a zener, it is supposed to be a MOV and it is also supposed
to be after fuse F4.

I have not figured out how voltage could have gotten to VR1 with the
fuses removed.

Either you or the board designer made a mistake, or you missed something
the previous 'tech' did. Can you get the aftermarket board's
installation instructions?

Any suggestions on where to go from here?

I highly recommend Pinhead's Bally/Stern rectifier board that we sell
(here in BC) and you might be able to get from Player 1 or perhaps
Toronto Pinball (Hamilton) of The Church Of The Silver Ball in
Missisagua (I think).
Ours is here and you can download the manual which gives you all the
wiring info which may apply to your rectifier board IF the designer
followed Bally/Stern labeling.

https://flippers.com/catalog_oc/bally-stern-replacement-rectifier-board-p-2678.html?search=pinhead

Maybe if multiple bridges were shorted. If BR3, ground to AC on the
fuse was shorted, and the HV diode from ground to AC was shorted.

We removed BR3 and replaced it because it seemed to test shorted.

But

the removed bridge tested fine in the diode test.

Wiring problems...

This after-market board has a small bridge in place of the HV 1N4004
diodes in the original.

That shouldn't matter IF it is rated at a high enough breakdown voltage.

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
--- Synchronet 3.18c-Win32 NewsLink 1.113

From Newsgroup: rec.games.pinball

On 5/26/21 6:21 PM, John Robertson wrote:

On 2021/05/26 3:00 p.m., cfhatprovidedotnet wrote:

The MOV is rated at 45 to 50 volts, so it did it's job!
it saw the 100v and FRIED, which is *exactly*
what it is supposed to do! This forces a fuse implosion,
which is what you want too. But when a MOV goes,
it GOES HARD AND VIOLENT. but that's what it's
supposed to do. it was preventing over voltage to
the coils in the game. Nothing else should have
fried, as the 43 volt coil power is unregulated, and
the bridge should be able to handle the 100v you
gave it.

They had ALL the fuses out. Nothing should have happened...

If the MOV blew because it was connected to the 230VAC, that would have destroyed the transformer - that winding can't handle more than about
500MA after all.

It might be the MOV is somehow hooked up to the line voltage...

John :-#)#

You can run without the MOV, but probably a good
idea to install a new one!

Also when i do a rectifier (transformer) board replacement,
after I'm done, you should *always* *always* *always* hook
the input connector up to 120 volts and test *all* the voltages.
Look at the schematics to get the exact two pins on the
input power connector. Frankly this takes all of about 1 minute
to do. All you need is two alligator clips on the rectifier board
connector 120vac pins. Or use the game's input plug (don't
attach the other two connectors.) And then use the test points
to check the voltages (6vdc, 240vdc, 15vdc, 6vac, 43vdc.)
If you had done that, problems would have been avoided...
(though that MOV would have still blown up!)


On Wednesday, May 26, 2021 at 5:26:01 PM UTC-4, John Robertson wrote:

On 2021/05/26 12:29 p.m., LexingtonVAPin wrote:

Long story....

Punchline is that the zener labelled as VR1 in the original board
caught
fire.

Two of us were called into the pinball museum to rescue a Bally
Paragon.

Another person tried to 'upgrade' the rectifier board to a new after-
market one. We were told the voltages were 'wrong' after the upgrade.

We found that the HV was low and the solenoid V was ~ 100 V.

A quick look and it appeared that a pair of wires off the transformer
from the HV and the solenoid AC were switched. We didn't see any
damage, but there was a smell that bothered us. Maybe the transformer? >>>>
So we rewired the board correctly from the transformer. Double-checked >>>> everything.

Wanted to check the AC coming out of the transformer. Removed fuses F1 >>>> - F5.

Turned it on. The zener in the VR1 location burned up and caught fire.

VR1 is NOT a zener, it is supposed to be a MOV and it is also supposed
to be after fuse F4.

I have not figured out how voltage could have gotten to VR1 with the
fuses removed.

Either you or the board designer made a mistake, or you missed something >>> the previous 'tech' did. Can you get the aftermarket board's
installation instructions?

Any suggestions on where to go from here?

I highly recommend Pinhead's Bally/Stern rectifier board that we sell
(here in BC) and you might be able to get from Player 1 or perhaps
Toronto Pinball (Hamilton) of The Church Of The Silver Ball in
Missisagua (I think).
Ours is here and you can download the manual which gives you all the
wiring info which may apply to your rectifier board IF the designer
followed Bally/Stern labeling.

https://flippers.com/catalog_oc/bally-stern-replacement-rectifier-board-p-2678.html?search=pinhead

Maybe if multiple bridges were shorted. If BR3, ground to AC on the
fuse was shorted, and the HV diode from ground to AC was shorted.

We removed BR3 and replaced it because it seemed to test shorted.

But

the removed bridge tested fine in the diode test.

Wiring problems...

This after-market board has a small bridge in place of the HV 1N4004
diodes in the original.

That shouldn't matter IF it is rated at a high enough breakdown voltage. >>>
John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

I said Zener. This is a weird aftermarket board. The other tech I was working with, who knows his stuff said he looked it up and it was a
Zener (60V if I recall correctly). But maybe we were both in shock as
that is the first time I have ever seen a board torch like that.

I have requested a schematic from the manufacturer. I don't recall the
name, but it was one I have never heard of before.

As to all of the precautions about wiring.....

Come on guys, we didn't do the initial mistake. As I said:

"Another person tried to 'upgrade' the rectifier board"

We were called in to mop up the mess.

"Either you or the board designer made a mistake, or you missed
something the previous 'tech' did."

Anything is possible. But we went over each and every connection. We
are not newbies on this, but have been doing electronics all of our
lives - between us 70 years. Did we miss something? I would bet my
left nut that we didn't. I found the two errors, moved the two wires.
Then we both went back through and checked every single connection. I checked it. He checked it. Then I went back through it again. Traced
the wire back to the secondary numbers on the transformer. Compared
that to the letters on the schematics. Three times.

#2 to E3, #6 to E4, and on down the list.

"Also when i do a rectifier (transformer) board replacement,
after I'm done, you should *always* *always* *always* hook
the input connector up to 120 volts and test *all* the voltages."

Exactly. We do that also. And that was what we were doing. Only the
120 VAC was connected. As you know, on these Bally boards, that comes
into the rectifier board, through a fuse and back out to the primary of
the transformer. Then the secondaries come back into the board. Pulling
all five fuses should have kept the voltage away from that [MOV / Zener
or whatever]. There is no bleeping way that MOV should ever have had
any voltage across it.

"If the MOV blew because it was connected to the 230VAC"

How would 230 VAC get to that MOV? On the other side of the removed F4?
That is my question!

"It might be the MOV is somehow hooked up to the line voltage... "

Only if the transformer was shorted internally. Even then, the removal
of the fuse should have prevented that MOV from seeing any power.

Here is my only theory so far:

* This board uses a small bridge for the HV, but the equivalent of CR4
or CR3 shorted.

* The diode inside the bridge of BR3 that goes from ground to the
(empty) F4 side of the MOV is also shorted.

"If the MOV blew because it was connected to the 230VAC, that would have destroyed the transformer"

When we came in to test the pin, first thing we did was disconnect all
outputs from the rectifier board. We tested the TP's on the rectifier
board. Saw ~100 V DC at TP5 and turned it off.

We thought we smelled something funky. We could not tell where from be
feared it was internal to the transformer.

Which is why I need to get 120 VAC hooked up to the primary and then
measure all the secondaries. Without understanding why that board
fried, the only thing I can think to do is to unsolder all the wires to
that fried board, put small wire caps on the end of the wires to keep
them from shorting, then measure one pair at a time.
--
http://orcalcoast.com/
--- Synchronet 3.18c-Win32 NewsLink 1.113

From Newsgroup: rec.games.pinball

On 2021/05/26 4:51 p.m., LexingtonVAPin wrote:

On 5/26/21 6:21 PM, John Robertson wrote:

On 2021/05/26 3:00 p.m., cfhatprovidedotnet wrote:

The MOV is rated at 45 to 50 volts, so it did it's job!
it saw the 100v and FRIED, which is *exactly*
what it is supposed to do! This forces a fuse implosion,
which is what you want too. But when a MOV goes,
it GOES HARD AND VIOLENT. but that's what it's
supposed to do. it was preventing over voltage to
the coils in the game. Nothing else should have
fried, as the 43 volt coil power is unregulated, and
the bridge should be able to handle the 100v you
gave it.

They had ALL the fuses out. Nothing should have happened...

If the MOV blew because it was connected to the 230VAC, that would
have destroyed the transformer - that winding can't handle more than
about 500MA after all.

It might be the MOV is somehow hooked up to the line voltage...

John :-#)#

You can run without the MOV, but probably a good
idea to install a new one!

Also when i do a rectifier (transformer) board replacement,
after I'm done, you should *always* *always* *always* hook
the input connector up to 120 volts and test *all* the voltages.
Look at the schematics to get the exact two pins on the
input power connector. Frankly this takes all of about 1 minute
to do. All you need is two alligator clips on the rectifier board
connector 120vac pins. Or use the game's input plug (don't
attach the other two connectors.) And then use the test points
to check the voltages (6vdc, 240vdc, 15vdc, 6vac, 43vdc.)
If you had done that, problems would have been avoided...
(though that MOV would have still blown up!)


On Wednesday, May 26, 2021 at 5:26:01 PM UTC-4, John Robertson wrote:>>>> On 2021/05/26 12:29 p.m., LexingtonVAPin wrote:

Long story....

Punchline is that the zener labelled as VR1 in the original board
caught
fire.

Two of us were called into the pinball museum to rescue a Bally
Paragon.

Another person tried to 'upgrade' the rectifier board to a new after- >>>>> market one. We were told the voltages were 'wrong' after the upgrade. >>>>>
We found that the HV was low and the solenoid V was ~ 100 V.

A quick look and it appeared that a pair of wires off the transformer >>>>> from the HV and the solenoid AC were switched. We didn't see any
damage, but there was a smell that bothered us. Maybe the transformer? >>>>>
So we rewired the board correctly from the transformer. Double-checked >>>>> everything.

Wanted to check the AC coming out of the transformer. Removed fuses

F1

- F5.

Turned it on. The zener in the VR1 location burned up and caught fire. >>>> VR1 is NOT a zener, it is supposed to be a MOV and it is also supposed >>>> to be after fuse F4.

I have not figured out how voltage could have gotten to VR1 with the >>>>> fuses removed.

Either you or the board designer made a mistake, or you missed
something
the previous 'tech' did. Can you get the aftermarket board's
installation instructions?

Any suggestions on where to go from here?

I highly recommend Pinhead's Bally/Stern rectifier board that we sell
(here in BC) and you might be able to get from Player 1 or perhaps
Toronto Pinball (Hamilton) of The Church Of The Silver Ball in
Missisagua (I think).
Ours is here and you can download the manual which gives you all the>>>> wiring info which may apply to your rectifier board IF the designer
followed Bally/Stern labeling.

https://flippers.com/catalog_oc/bally-stern-replacement-rectifier-board-p-2678.html?search=pinhead

Maybe if multiple bridges were shorted. If BR3, ground to AC on the>>>>> fuse was shorted, and the HV diode from ground to AC was shorted.

We removed BR3 and replaced it because it seemed to test shorted.

But

the removed bridge tested fine in the diode test.

Wiring problems...

This after-market board has a small bridge in place of the HV 1N4004 >>>>> diodes in the original.

That shouldn't matter IF it is rated at a high enough breakdown
voltage.

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

I said Zener.  This is a weird aftermarket board.  The other tech I was working with, who knows his stuff said he looked it up and it was a
Zener (60V if I recall correctly).   But maybe we were both in shock as that is the first time I have ever seen a board torch like that.

I have requested a schematic from the manufacturer.  I don't recall the name, but it was one I have never heard of before.

As to all of the precautions about wiring.....

Come on guys, we didn't do the initial mistake.  As I said:

"Another person tried to 'upgrade' the rectifier board"

We were called in to mop up the mess.

"Either you or the board designer made a mistake, or you missed
something the previous 'tech' did."

Anything is possible.  But we went over each and every connection.  We
are not newbies on this, but have been doing electronics all of our
lives - between us 70 years.  Did we miss something?   I

would bet my

left nut that we didn't.   I found the two errors, moved the two wires. Then we both went back through and checked every single connection. 

I

checked it.  He checked it.  Then I went back through it again.  Traced the wire back to the secondary numbers on the transformer.  Compared
that to the letters on the schematics.  Three times.

#2 to E3, #6 to E4, and on down the list.

"Also when i do a rectifier (transformer) board replacement,
after I'm done, you should *always* *always* *always* hook
the input connector up to 120 volts and test *all* the voltages."

Exactly.  We do that also.  And that was what we were doing.  Only the 120 VAC was connected.  As you know, on these Bally boards, that comes
into the rectifier board, through a fuse and back out to the primary of
the transformer. Then the secondaries come back into the board.  Pulling all five fuses should have kept the voltage away from that [MOV / Zener
or whatever].  There is no bleeping way that MOV should ever have had
any voltage across it.

"If the MOV blew because it was connected to the 230VAC"

How would 230 VAC get to that MOV?  On the other side of the removed F4? That is my question!

"It might be the MOV is somehow hooked up to the line voltage... "

Only if the transformer was shorted internally.  Even then, the removal
of the fuse should have prevented that MOV from seeing any power.

Here is my only theory so far:

* This board uses a small bridge for the HV, but the equivalent of CR4 > or CR3 shorted.

* The diode inside the bridge of BR3 that goes from ground to the
(empty) F4 side of the MOV is also shorted.

"If the MOV blew because it was connected to the 230VAC, that would have destroyed the transformer"

When we came in to test the pin, first thing we did was disconnect all > outputs from the rectifier board.  We tested the TP's on the rectifier
board.  Saw ~100 V DC at TP5 and turned it off.

We thought we smelled something funky.  We could not tell where from be feared it was internal to the transformer.

Which is why I need to get 120 VAC hooked up to the primary and then
measure all the secondaries.  Without understanding why that board
fried, the only thing I can think to do is to unsolder all the wires to
that fried board, put small wire caps on the end of the wires to keep
them from shorting, then measure one pair at a time.

At this point I would unsolder the rectifier board and start over.
As for testing the transformer, why not (after removing the rectifier
board) simply hook the transformer lugs E1 & E2 (fused or use a 40W to
100W lamp in series - the Dim Bulb Test) to the 120 line and then
monitor the other lugs. I would start with the 230VAC (E5 & E6), if that is bad, then nothing will save the transformer...
If you are using a light bulb in series then all secondary voltages will be low. The Dim Bulb Test is to see if the transformer is shorted or
not. The bulb should be bright for just a moment after power is applied. https://antiqueradio.org/dimbulb.htm
I've used this trick since the 70s.
John :-#)#
--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
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From Newsgroup: rec.games.pinball

John Robertson wrote:

At this point I would unsolder the rectifier board and start over.

Yeah, dump that shit.

One mistake you did make was using original schematics on an aftermarket
board that has different parts (unless you verified the layout + traces)
on it - how do you know where you were putting the wires from the
transformer was correct?

Pull the board like john says and test the transformer separately. I'd replace the suspect rectifier board at this point with a known good
remake anyway, sounds like a bad design the way it came out.

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From Newsgroup: rec.games.pinball

On 5/26/21 8:18 PM, John Robertson wrote:

On 2021/05/26 4:51 p.m., LexingtonVAPin wrote:

On 5/26/21 6:21 PM, John Robertson wrote:

On 2021/05/26 3:00 p.m., cfhatprovidedotnet wrote:

The MOV is rated at 45 to 50 volts, so it did it's job!
it saw the 100v and FRIED, which is *exactly*
what it is supposed to do! This forces a fuse implosion,
which is what you want too. But when a MOV goes,
it GOES HARD AND VIOLENT. but that's what it's
supposed to do. it was preventing over voltage to
the coils in the game. Nothing else should have
fried, as the 43 volt coil power is unregulated, and
the bridge should be able to handle the 100v you
gave it.

They had ALL the fuses out. Nothing should have happened...

If the MOV blew because it was connected to the 230VAC, that would
have destroyed the transformer - that winding can't handle more than
about 500MA after all.

It might be the MOV is somehow hooked up to the line voltage...

John :-#)#

You can run without the MOV, but probably a good
idea to install a new one!

Also when i do a rectifier (transformer) board replacement,
after I'm done, you should *always* *always* *always* hook
the input connector up to 120 volts and test *all* the voltages.
Look at the schematics to get the exact two pins on the
input power connector. Frankly this takes all of about 1 minute
to do. All you need is two alligator clips on the rectifier board
connector 120vac pins. Or use the game's input plug (don't
attach the other two connectors.) And then use the test points
to check the voltages (6vdc, 240vdc, 15vdc, 6vac, 43vdc.)
If you had done that, problems would have been avoided...
(though that MOV would have still blown up!)


On Wednesday, May 26, 2021 at 5:26:01 PM UTC-4, John Robertson wrote: >>>>> On 2021/05/26 12:29 p.m., LexingtonVAPin wrote:

Long story....

Punchline is that the zener labelled as VR1 in the original board >>>>>> caught
fire.

Two of us were called into the pinball museum to rescue a Bally
Paragon.

Another person tried to 'upgrade' the rectifier board to a new after- >>>>>> market one. We were told the voltages were 'wrong' after the upgrade. >>>>>>
We found that the HV was low and the solenoid V was ~ 100 V.

A quick look and it appeared that a pair of wires off the transformer >>>>>> from the HV and the solenoid AC were switched. We didn't see any
damage, but there was a smell that bothered us. Maybe the
transformer?

So we rewired the board correctly from the transformer.
Double-checked
everything.

Wanted to check the AC coming out of the transformer. Removed fuses

F1

- F5.

Turned it on. The zener in the VR1 location burned up and caught
fire.

VR1 is NOT a zener, it is supposed to be a MOV and it is also supposed >>>>> to be after fuse F4.

I have not figured out how voltage could have gotten to VR1 with the >>>>>> fuses removed.

Either you or the board designer made a mistake, or you missed
something
the previous 'tech' did. Can you get the aftermarket board's
installation instructions?

Any suggestions on where to go from here?

I highly recommend Pinhead's Bally/Stern rectifier board that we sell >>>>> (here in BC) and you might be able to get from Player 1 or perhaps
Toronto Pinball (Hamilton) of The Church Of The Silver Ball in
Missisagua (I think).
Ours is here and you can download the manual which gives you all the >>>>> wiring info which may apply to your rectifier board IF the designer
followed Bally/Stern labeling.

https://flippers.com/catalog_oc/bally-stern-replacement-rectifier-board-p-2678.html?search=pinhead

Maybe if multiple bridges were shorted. If BR3, ground to AC on the >>>>>> fuse was shorted, and the HV diode from ground to AC was shorted.

We removed BR3 and replaced it because it seemed to test shorted.

But

the removed bridge tested fine in the diode test.

Wiring problems...

This after-market board has a small bridge in place of the HV 1N4004 >>>>>> diodes in the original.

That shouldn't matter IF it is rated at a high enough breakdown
voltage.

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

I said Zener.  This is a weird aftermarket board.  The other tech I
was working with, who knows his stuff said he looked it up and it was
a Zener (60V if I recall correctly).   But maybe we were both in shock
as that is the first time I have ever seen a board torch like that.

I have requested a schematic from the manufacturer.  I don't recall
the name, but it was one I have never heard of before.

As to all of the precautions about wiring.....

Come on guys, we didn't do the initial mistake.  As I said:

"Another person tried to 'upgrade' the rectifier board"

We were called in to mop up the mess.

"Either you or the board designer made a mistake, or you missed
something the previous 'tech' did."

Anything is possible.  But we went over each and every connection.  We
are not newbies on this, but have been doing electronics all of our
lives - between us 70 years.  Did we miss something?   I

would bet my

left nut that we didn't.   I found the two errors, moved the two
wires. Then we both went back through and checked every single
connection.

I

checked it.  He checked it.  Then I went back through it again.
Traced the wire back to the secondary numbers on the transformer.
Compared that to the letters on the schematics.  Three times.

#2 to E3, #6 to E4, and on down the list.

"Also when i do a rectifier (transformer) board replacement,
after I'm done, you should *always* *always* *always* hook
the input connector up to 120 volts and test *all* the voltages."

Exactly.  We do that also.  And that was what we were doing.  Only the >> 120 VAC was connected.  As you know, on these Bally boards, that comes
into the rectifier board, through a fuse and back out to the primary of

the transformer. Then the secondaries come back into the board.
Pulling all five fuses should have kept the voltage away from that
[MOV / Zener

or whatever].  There is no bleeping way that MOV should ever have had
any voltage across it.

"If the MOV blew because it was connected to the 230VAC"

How would 230 VAC get to that MOV?  On the other side of the removed
F4? That is my question!

"It might be the MOV is somehow hooked up to the line voltage... "

Only if the transformer was shorted internally.  Even then, the
removal of the fuse should have prevented that MOV from seeing any power.

Here is my only theory so far:

* This board uses a small bridge for the HV, but the equivalent of CR4
or CR3 shorted.

* The diode inside the bridge of BR3 that goes from ground to the
(empty) F4 side of the MOV is also shorted.

"If the MOV blew because it was connected to the 230VAC, that would
have destroyed the transformer"

When we came in to test the pin, first thing we did was disconnect all
outputs from the rectifier board.  We tested the TP's on the rectifier
board.  Saw ~100 V DC at TP5 and turned it off.

We thought we smelled something funky.  We could not tell where from
be feared it was internal to the transformer.

Which is why I need to get 120 VAC hooked up to the primary and then
measure all the secondaries.  Without understanding why that board

fried, the only thing I can think to do is to unsolder all the wires to

that fried board, put small wire caps on the end of the wires to keep
them from shorting, then measure one pair at a time.

At this point I would unsolder the rectifier board and start over.

As for testing the transformer, why not (after removing the rectifier
board) simply hook the transformer lugs E1 & E2 (fused or use a 40W to
100W lamp in series - the Dim Bulb Test) to the 120 line and then
monitor the other lugs. I would start with the 230VAC (E5 & E6), if that
is bad, then nothing will save the transformer...

If you are using a light bulb in series then all secondary voltages will
be low. The Dim Bulb Test is to see if the transformer is shorted or
not. The bulb should be bright for just a moment after power is applied.

https://antiqueradio.org/dimbulb.htm

I've used this trick since the 70s.

John :-#)#

The board is completely unsoldered at the moment, so that will be easy
to do.

Putting a light bulb in series is a great idea! Thank you. I had
forgotten that trick.

I believe I know the answer to this, but thought I would ask:

If the 230 VAC is fried, can I use the other taps and expect the
transformer to last? I figure we could slap that one in a pin that has
LED displays.

If, as expected, the answer is 'not a good idea', I guess we will just
have to troll the usual suspects for a used replacement? Do you have
any suggestions?
--
http://orcalcoast.com/
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From Newsgroup: rec.games.pinball

On 5/27/21 10:05 AM, seymour.shabow wrote:

John Robertson wrote:

At this point I would unsolder the rectifier board and start over.

Yeah, dump that shit.

One mistake you did make was using original schematics on an aftermarket board that has different parts (unless you verified the layout + traces)
on it - how do you know where you were putting the wires from the transformer was correct?

Pull the board like john says and test the transformer separately.  I'd replace the suspect rectifier board at this point with a known good
remake anyway, sounds like a bad design the way it came out.

"One mistake you did make was using original schematics on an
aftermarket board that has different parts (unless you verified the
layout + traces) on it"

We did trace the letters on the board to which fuse and to which bridge.

Since it appeared that the original tech cross wired the 49 V AC and the
173 V AC, we were especially careful to check that the traces from E3
went to F4 which went to BR3, E4 to the other side; and E5 (to F2) / E6
went to the HV bridge.

So it appears that the letters on the aftermarket board conform to the original board.

I am pretty sure that the only major difference between the aftermarket
board and the original Bally board is the use of a bridge for the HV.
Plus the bridges are not attached on the back, but facing up with their
own heat sinks (like all other aftermarket Bally rectifier boards).
Other than that, it has the same characteristics of the original, both
good and bad.

It is interesting to see how these aftermarket boards are designed.
Some copy the original. Some try to improve.
I know they have to be plug compatible, but I would at least remove the
AC from the common ground. I think that could be done by isolating J3-2
and J1-2 from the other grounds and sending it directly to E8. I just
do not like sending AC to the common DC ground.
Maybe that is just asking for trouble with little benefit.
--
http://orcalcoast.com/
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From Newsgroup: rec.games.pinball

LexingtonVAPin wrote:

I am pretty sure that the only major difference between the aftermarket board and the original Bally board is the use of a bridge for the HV.
Plus the bridges are not attached on the back, but facing up with their
own heat sinks (like all other aftermarket Bally rectifier boards).
Other than that, it has the same characteristics of the original, both
good and bad.

Well, I don't think I'd replace a MOV with a Zener. The replacement
boards that stick with the original design but correct the heat
deficiencies are the way I go.
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From Newsgroup: rec.games.pinball

LexingtonVAPin wrote:

If, as expected, the answer is 'not a good idea', I guess we will just
have to troll the usual suspects for a used replacement? Do you have
any suggestions?

I have a couple extras myself but I have to make sure I'm not selling
one I need for a project..... there's a pile of projects still here that
may or may not be missing that part.
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From Newsgroup: rec.games.pinball

On 2021/05/27 7:48 a.m., LexingtonVAPin wrote:

On 5/26/21 8:18 PM, John Robertson wrote:

On 2021/05/26 4:51 p.m., LexingtonVAPin wrote:

On 5/26/21 6:21 PM, John Robertson wrote:

On 2021/05/26 3:00 p.m., cfhatprovidedotnet wrote:...

At this point I would unsolder the rectifier board and start over.

As for testing the transformer, why not (after removing the rectifier >> board) simply hook the transformer lugs E1 & E2 (fused or use a 40W to
100W lamp in series - the Dim Bulb Test) to the 120 line and then
monitor the other lugs. I would start with the 230VAC (E5 & E6), if
that is bad, then nothing will save the transformer...

If you are using a light bulb in series then all secondary voltages
will be low. The Dim Bulb Test is to see if the transformer is shorted
or not. The bulb should be bright for just a moment after power is
applied.

https://antiqueradio.org/dimbulb.htm

I've used this trick since the 70s.

John :-#)#

The board is completely unsoldered at the moment, so that will be easy > to do.

Putting a light bulb in series is a great idea!  Thank you.  I had forgotten that trick.

I believe I know the answer to this, but thought I would ask:

If the 230 VAC is fried, can I use the other taps and expect the
transformer to last?   I figure we could slap that one in a pin that has LED displays.

No, that won't work. Once one winding has failed (shorted) in a
transformer it then turns into a heat source. It will warm your game
depending on how big the primary fuse is...

If, as expected, the answer is 'not a good idea', I guess we will just > have to troll the usual suspects for a used replacement?   Do

you have

any suggestions?

The lamp test will let you know if the Xformer is shorted without the
blowing of fuses and possibly lots of smoke. If it is then start hunting... John :-#)#
--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
--- Synchronet 3.18c-Win32 NewsLink 1.113

From Newsgroup: rec.games.pinball

On 5/27/21 12:31 PM, John Robertson wrote:

On 2021/05/27 7:48 a.m., LexingtonVAPin wrote:

On 5/26/21 8:18 PM, John Robertson wrote:

On 2021/05/26 4:51 p.m., LexingtonVAPin wrote:

On 5/26/21 6:21 PM, John Robertson wrote:

On 2021/05/26 3:00 p.m., cfhatprovidedotnet wrote:...

At this point I would unsolder the rectifier board and start over.

As for testing the transformer, why not (after removing the rectifier
board) simply hook the transformer lugs E1 & E2 (fused or use a 40W to

100W lamp in series - the Dim Bulb Test) to the 120 line and then
monitor the other lugs. I would start with the 230VAC (E5 & E6), if
that is bad, then nothing will save the transformer...

If you are using a light bulb in series then all secondary voltages
will be low. The Dim Bulb Test is to see if the transformer is shorted

or not. The bulb should be bright for just a moment after power is
applied.

https://antiqueradio.org/dimbulb.htm

I've used this trick since the 70s.

John :-#)#

The board is completely unsoldered at the moment, so that will be easy
to do.

Putting a light bulb in series is a great idea!  Thank you.  I had
forgotten that trick.

I believe I know the answer to this, but thought I would ask:

If the 230 VAC is fried, can I use the other taps and expect the
transformer to last?   I figure we could slap that one in a pin that
has LED displays.

No, that won't work. Once one winding has failed (shorted) in a
transformer it then turns into a heat source. It will warm your game depending on how big the primary fuse is...

If, as expected, the answer is 'not a good idea', I guess we will just
have to troll the usual suspects for a used replacement?   Do

you have

any suggestions?

The lamp test will let you know if the Xformer is shorted without the blowing of fuses and possibly lots of smoke. If it is then start hunting...

John :-#)#

Thanks John.

I figured that the transformer would not be any good with a winding
blown. Had not figured out that the winding would become a heat source.

Good to know why it would not be any good.
--
http://orcalcoast.com/
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From Newsgroup: rec.games.pinball

On 5/27/21 11:53 AM, seymour.shabow wrote:

LexingtonVAPin wrote:

If, as expected, the answer is 'not a good idea', I guess we will just
have to troll the usual suspects for a used replacement?   Do you have
any suggestions?

I have a couple extras myself but I have to make sure I'm not selling
one I need for a project..... there's a pile of projects still here that
may or may not be missing that part.

Thanks Scott. I might get into the museum on Sunday (it is a one hour
drive each way). I will come up with a way to safely wire in that lamp
in series with primary, then start testing.

Will let everyone know what happens.
--
http://orcalcoast.com/
--- Synchronet 3.18c-Win32 NewsLink 1.113

From Newsgroup: rec.games.pinball

On 5/27/21 12:31 PM, John Robertson wrote:

On 2021/05/27 7:48 a.m., LexingtonVAPin wrote:

On 5/26/21 8:18 PM, John Robertson wrote:

On 2021/05/26 4:51 p.m., LexingtonVAPin wrote:

On 5/26/21 6:21 PM, John Robertson wrote:

On 2021/05/26 3:00 p.m., cfhatprovidedotnet wrote:...

At this point I would unsolder the rectifier board and start over.

As for testing the transformer, why not (after removing the rectifier
board) simply hook the transformer lugs E1 & E2 (fused or use a 40W to

100W lamp in series - the Dim Bulb Test) to the 120 line and then
monitor the other lugs. I would start with the 230VAC (E5 & E6), if
that is bad, then nothing will save the transformer...

If you are using a light bulb in series then all secondary voltages
will be low. The Dim Bulb Test is to see if the transformer is shorted

or not. The bulb should be bright for just a moment after power is
applied.

https://antiqueradio.org/dimbulb.htm

I've used this trick since the 70s.

John :-#)#

The board is completely unsoldered at the moment, so that will be easy
to do.

Putting a light bulb in series is a great idea!  Thank you.  I had
forgotten that trick.

I believe I know the answer to this, but thought I would ask:

If the 230 VAC is fried, can I use the other taps and expect the
transformer to last?   I figure we could slap that one in a pin that
has LED displays.

No, that won't work. Once one winding has failed (shorted) in a
transformer it then turns into a heat source. It will warm your game depending on how big the primary fuse is...

If, as expected, the answer is 'not a good idea', I guess we will just
have to troll the usual suspects for a used replacement?   Do

you have

any suggestions?

The lamp test will let you know if the Xformer is shorted without the blowing of fuses and possibly lots of smoke. If it is then start hunting...

John :-#)#

I went down to the museum on Sunday, and met with another volunteer tech.

On the aftermarket board, the position where the MOV would go on the
original board is marked as ZR1 on this board. That is why we thought
it was a Zener. We replaced it with a MOV from an old Bally board.

All secondary voltages were good on the transformer with nothing
connected but primary. Connected it to the rectifier board, still good.
Installed fuses, still good. We did low voltages first, then moved up
to higher ones.

We installed the transformer and board into the backbox and hooked it
up. Tested good. Connected the voltage regulator board - good, then MPU
- booted, then lamp board - good, sound & solenoids - all fine.

To review, the previous person crossed the secondaries of the HV and
solenoid on the rectifier board. We think that VR1 (or ZR1?) became a
direct short as a result of this mistake.

We noticed that when previous people replaced the 0.156 plugs, they
neglected to install keying plugs. We figured either we inverted J2, or
were off by one pin. We went back through all reworked plugs and
installed keys.

If the plug was flipped upside down, AC at 6 and 7 would go to 4 & 5
which are spare and ground. 4 appears to have no connection.

If we are off by a pin, AC would go to 5 & 6 or 7 & 8. 5 is ground, 6 is
AC primary. 7 is AC primary, 8 is key. None of those seem to get any
power to VR1 with F4 removed.

If we grounded the AC, the rectifier board is tied to earth ground.
That would ground the AC line (assuming the pin is earth grounded).

I never realized that there is not a cabinet 8A fuse on these early
Bally SS pins (according to the schematic).
--
http://orcalcoast.com/
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