From Newsgroup: rec.games.pinball

I am working on a System 6 (not 6A) board out of a Firepower. The board came with the combo ROM installed at IC14 and the board had a printed label on it that said “This CPU is a dedicated Firepower.” The board has had the following modifications done to it.
1J31 and 1J41 have been jumped to fix the memory protect trace routing fault. IC9 and IC10 have been removed and the data lines jumped.
IC14 pin 21 has had the trace cut to get rid of the 5v.
IC14 pin 21 has been jumped to IC30 pin 14.
All of the above make sense and I understand it within the context of the combo ROM. But here’s where the modifications get interesting.
The trace from IC14 pin 18 to IC17 has been cut.
IC14 pin 18 is jumped to IC15 pin 3.
IC14 pin 20 is jumped to IC15 pin 1.
IC15 is socketed on this board and contains an LS139.
Lastly, there are no jumpers installed at J3 and J4.
Anyone ever see this config before and can comment about its reliability and stability compared to the other methods out there for this conversion? Thanks.
Front of board
https://photos.app.goo.gl/fHS4YhNfTdCjK9ED8
Back of board
https://photos.app.goo.gl/RGTZrnhbHyjbdHfQ8
viperrwk
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From Newsgroup: rec.games.pinball

On 2020/10/02 9:12 a.m., trader...@gmail.com wrote:

I am working on a System 6 (not 6A) board out of a Firepower. The board came with the combo ROM installed at IC14 and the board had a printed label on it that said “This CPU is a dedicated Firepower.” The board has had the following modifications done to it.

1J31 and 1J41 have been jumped to fix the memory protect trace routing fault.

IC9 and IC10 have been removed and the data lines jumped. (I've seen this before - JR)

IC14 pin 21 has had the trace cut to get rid of the 5v.

IC14 pin 21 has been jumped to IC30 pin 14 (they used a 2732, right? - needs A11 - JR).

All of the above make sense and I understand it within the context of the combo ROM. But here’s where the modifications get interesting.>
The trace from IC14 pin 18 to IC17 has been cut.

IC14 pin 18 is jumped to IC15 pin 3.

IC14 pin 20 is jumped to IC15 pin 1.

IC15 is socketed on this board and contains an LS139.

The above are needed to expand the memory allocation table for U14 from
2K to 4K

Lastly, there are no jumpers installed at J3 and J4. (I'd have to pull the schematics for those, and I'm busy - JR)

Anyone ever see this config before and can comment about its reliability and stability compared to the other methods out there for this conversion? Thanks.

Front of board
https://photos.app.goo.gl/fHS4YhNfTdCjK9ED8

Back of board
https://photos.app.goo.gl/RGTZrnhbHyjbdHfQ8

viperrwk

Hi Bob,
If it works then it is reliable - after 40 years...
Are any of the cruddy black RN sockets used for the combo EPROM?
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 3.18a-Linux NewsLink 1.113

From Newsgroup: rec.games.pinball

On Friday, October 2, 2020 at 12:45:50 PM UTC-4, John Robertson wrote:

On 2020/10/02 9:12 a.m., trader...@gmail.com wrote:

I am working on a System 6 (not 6A) board out of a Firepower. The board came with the combo ROM installed at IC14 and the board had a printed label on it that said “This CPU is a dedicated Firepower.” The board has had the following modifications done to it.

1J31 and 1J41 have been jumped to fix the memory protect trace routing fault.

IC9 and IC10 have been removed and the data lines jumped. (I've seen this before - JR)

IC14 pin 21 has had the trace cut to get rid of the 5v.

IC14 pin 21 has been jumped to IC30 pin 14 (they used a 2732, right? - needs A11 - JR).

All of the above make sense and I understand it within the context of the combo ROM. But here’s where the modifications get interesting.

The trace from IC14 pin 18 to IC17 has been cut.

IC14 pin 18 is jumped to IC15 pin 3.

IC14 pin 20 is jumped to IC15 pin 1.

IC15 is socketed on this board and contains an LS139.

The above are needed to expand the memory allocation table for U14 from
2K to 4K

Lastly, there are no jumpers installed at J3 and J4. (I'd have to pull the schematics for those, and I'm busy - JR)

Anyone ever see this config before and can comment about its reliability and stability compared to the other methods out there for this conversion? Thanks.

Front of board
https://photos.app.goo.gl/fHS4YhNfTdCjK9ED8

Back of board
https://photos.app.goo.gl/RGTZrnhbHyjbdHfQ8

viperrwk

Hi Bob,

If it works then it is reliable - after 40 years...

Are any of the cruddy black RN sockets used for the combo EPROM?

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 3.18a-Linux NewsLink 1.113

From Newsgroup: rec.games.pinball

On Friday, October 2, 2020 at 12:45:50 PM UTC-4, John Robertson wrote:

On 2020/10/02 9:12 a.m., trader...@gmail.com wrote:

I am working on a System 6 (not 6A) board out of a Firepower. The board came with the combo ROM installed at IC14 and the board had a printed label on it that said “This CPU is a dedicated Firepower.” The board has had the following modifications done to it.

1J31 and 1J41 have been jumped to fix the memory protect trace routing fault.

IC9 and IC10 have been removed and the data lines jumped. (I've seen this before - JR)

IC14 pin 21 has had the trace cut to get rid of the 5v.

IC14 pin 21 has been jumped to IC30 pin 14 (they used a 2732, right? - needs A11 - JR).

All of the above make sense and I understand it within the context of the combo ROM. But here’s where the modifications get interesting.

The trace from IC14 pin 18 to IC17 has been cut.

IC14 pin 18 is jumped to IC15 pin 3.

IC14 pin 20 is jumped to IC15 pin 1.

IC15 is socketed on this board and contains an LS139.

The above are needed to expand the memory allocation table for U14 from
2K to 4K

Lastly, there are no jumpers installed at J3 and J4. (I'd have to pull the schematics for those, and I'm busy - JR)

Anyone ever see this config before and can comment about its reliability and stability compared to the other methods out there for this conversion? Thanks.

Front of board
https://photos.app.goo.gl/fHS4YhNfTdCjK9ED8

Back of board
https://photos.app.goo.gl/RGTZrnhbHyjbdHfQ8

viperrwk

Hi Bob,

If it works then it is reliable - after 40 years...

Are any of the cruddy black RN sockets used for the combo EPROM?

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."

The board as pictured is in an early state before soldered parts removal.
The combo ROM was indeed a 2732. IC14 did have the crappy socket that is being replaced.
J3 ties IC14 pin 20 to pins 4 and 15 of IC15. J4 ties IC14 pin 20 to pin 5 of IC15. Per the notes of the schematic:
"When IC14 game ROM is used in place of PROMs, jumper J3 must be connected and J4 removed (IC address 6000 16). When IC14 game ROM and PROMs are used, jumper J4 must be connected and J3 removed (IC address 6800 16)."
Trying to decide if I keep this setup or go with the Duncan Brown method. viperrwk
--- Synchronet 3.18a-Linux NewsLink 1.113

From Newsgroup: rec.games.pinball

On 2020/10/02 11:44 a.m., trader...@gmail.com wrote:

On Friday, October 2, 2020 at 12:45:50 PM UTC-4, John Robertson wrote:

On 2020/10/02 9:12 a.m., trader...@gmail.com wrote:

I am working on a System 6 (not 6A) board out of a Firepower. The board came with the combo ROM installed at IC14 and the board had a printed label on it that said “This CPU is a dedicated Firepower.” The board has had the following modifications done to it.

1J31 and 1J41 have been jumped to fix the memory protect trace routing fault.

IC9 and IC10 have been removed and the data lines jumped. (I've seen this before - JR)

IC14 pin 21 has had the trace cut to get rid of the 5v.

IC14 pin 21 has been jumped to IC30 pin 14 (they used a 2732, right? - needs A11 - JR).

All of the above make sense and I understand it within the context of the combo ROM. But here’s where the modifications get interesting.

The trace from IC14 pin 18 to IC17 has been cut.

IC14 pin 18 is jumped to IC15 pin 3.

IC14 pin 20 is jumped to IC15 pin 1.

IC15 is socketed on this board and contains an LS139.

The above are needed to expand the memory allocation table for U14 from
2K to 4K

Lastly, there are no jumpers installed at J3 and J4. (I'd have to pull the schematics for those, and I'm busy - JR)

Anyone ever see this config before and can comment about its reliability and stability compared to the other methods out there for this conversion? Thanks.

Front of board
https://photos.app.goo.gl/fHS4YhNfTdCjK9ED8

Back of board
https://photos.app.goo.gl/RGTZrnhbHyjbdHfQ8

viperrwk

Hi Bob,

If it works then it is reliable - after 40 years...

Are any of the cruddy black RN sockets used for the combo EPROM?

John :-#)#

The board as pictured is in an early state before soldered parts removal.
The combo ROM was indeed a 2732. IC14 did have the crappy socket that is being replaced.
J3 ties IC14 pin 20 to pins 4 and 15 of IC15. J4 ties IC14 pin 20 to pin 5 of IC15. Per the notes of the schematic:

"When IC14 game ROM is used in place of PROMs, jumper J3 must be connected and J4 removed (IC address 6000 16). When IC14 game ROM and PROMs are used, jumper J4 must be connected and J3 removed (IC address 6800 16)."

Trying to decide if I keep this setup or go with the Duncan Brown method.

viperrwk

All I can say is if the board is working, then why change it? I have
converted a number of boards to work with 2532s, which is the easier conversion, but this seems viable.
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 3.18a-Linux NewsLink 1.113

From Newsgroup: rec.games.pinball

On Friday, October 2, 2020 at 3:03:28 PM UTC-4, John Robertson wrote:

On 2020/10/02 11:44 a.m., trader...@gmail.com wrote:

On Friday, October 2, 2020 at 12:45:50 PM UTC-4, John Robertson wrote:

On 2020/10/02 9:12 a.m., trader...@gmail.com wrote:

I am working on a System 6 (not 6A) board out of a Firepower. The board came with the combo ROM installed at IC14 and the board had a printed label on it that said “This CPU is a dedicated Firepower.” The board has had the following modifications done to it.

1J31 and 1J41 have been jumped to fix the memory protect trace routing fault.

IC9 and IC10 have been removed and the data lines jumped. (I've seen this before - JR)

IC14 pin 21 has had the trace cut to get rid of the 5v.

IC14 pin 21 has been jumped to IC30 pin 14 (they used a 2732, right? - needs A11 - JR).

All of the above make sense and I understand it within the context of the combo ROM. But here’s where the modifications get interesting.

The trace from IC14 pin 18 to IC17 has been cut.

IC14 pin 18 is jumped to IC15 pin 3.

IC14 pin 20 is jumped to IC15 pin 1.

IC15 is socketed on this board and contains an LS139.

The above are needed to expand the memory allocation table for U14 from >> 2K to 4K

Lastly, there are no jumpers installed at J3 and J4. (I'd have to pull the schematics for those, and I'm busy - JR)

Anyone ever see this config before and can comment about its reliability and stability compared to the other methods out there for this conversion? Thanks.

Front of board
https://photos.app.goo.gl/fHS4YhNfTdCjK9ED8

Back of board
https://photos.app.goo.gl/RGTZrnhbHyjbdHfQ8

viperrwk

Hi Bob,

If it works then it is reliable - after 40 years...

Are any of the cruddy black RN sockets used for the combo EPROM?

John :-#)#

The board as pictured is in an early state before soldered parts removal. The combo ROM was indeed a 2732. IC14 did have the crappy socket that is being replaced.
J3 ties IC14 pin 20 to pins 4 and 15 of IC15. J4 ties IC14 pin 20 to pin 5 of IC15. Per the notes of the schematic:

"When IC14 game ROM is used in place of PROMs, jumper J3 must be connected and J4 removed (IC address 6000 16). When IC14 game ROM and PROMs are used, jumper J4 must be connected and J3 removed (IC address 6800 16)."

Trying to decide if I keep this setup or go with the Duncan Brown method.

viperrwk

All I can say is if the board is working, then why change it? I have converted a number of boards to work with 2532s, which is the easier conversion, but this seems viable.
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 appreciate the sentiment. The issue is the machine was not reliable with this board in it but there were a number of (typical) issues which I am addressing (PS, MDB, driver, sound/connectors, sockets, burnt up components, etc.)
What I don't want is to get it all back together, get it to the owner, put it in the game and then issues start cropping up because this mod isn't as effective as the other one. Which is why I'm asking if anyone else has seen this particular mod for Firepower and has any thoughts on its efficacy as compared to the Duncan Brown method.
If no one can specifically address that question I will likely put it back the way it was and see what happens then come back to this thread after a while and let people know if it's a reliable mod or not.
viperrwk
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