JROK SOHS (Save Our High Scores) NVRAM mod failures

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JROK SOHS (Save Our High Scores) NVRAM mod failures

I performed the JROK NVRAM mods to 3 of my games. Only 1 of them has had no problems after the mod.


Q*Bert working perfectly.

Super-PacMan: After a week off, power up and it immediately coins up and starts a game and plays multiple sounds on top of each other. High score table zapped but main high score still there. Power cycle and no subsequent problems. Had burned in this board for 24+ hours before mod and used about 8 hours after mod before shutdown, and power cycled a few times over a month without loss of HS or other problems before it flaked out.


Frogger: Kept scores for a week or so, then had dots instead of names for high score list. A few days later all scores cleared with JROK default initials.


Voltage on all boards tests ~5.0 volts. QB/SuperPac have original power supplies, QBert has the cap mod to the reset line as well. Frogger has newer switcher.

All NVRAMs were manufactured in 2008, new stock from ST. Not dealing with old Dallas pulls.

Anyone else see failures with these mods?
 
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I did my super pac a few years ago and not a single problem with it.
I have a braze HSS kit in my frogger and its bulletproof too.
My qbert just has a lithium battery on it.

What do you have you +5 set to on these games? Measure at the pcb and make sure its around 5.05v. If its dipping down too low you could have issues with the NV ram.
 
Voltage on all boards tests ~5.0 volts. QB/SuperPac have original power supplies, QBert has the cap mod to the reset line as well. Frogger has newer switcher.

Put the original RAM chip back in the superpac and measure the voltage at the chip. Same with the frogger, measure at say the ROM socket right next to the NVRAM.

It needs to be as close to 5v as possible otherwise the RAM goes into the write protect state.

- James
 
Digging up a SUPER dead thread here, does anyone has a copy of the Super Pacman ROMS for the JROK upgrade?
I have tried to files from his website https://www.jrok.com/sohs/superpac/superpac.html on two different sets of 2764s along with mutiple SRAM chips and it wont work.
If I go back to original roms it works,
If I go to original roms and leave in SRAM it works, so I think SRAM is good.

Any help is appreciated.
 
Digging up a SUPER dead thread here, does anyone has a copy of the Super Pacman ROMS for the JROK upgrade?
I have tried to files from his website https://www.jrok.com/sohs/superpac/superpac.html on two different sets of 2764s along with mutiple SRAM chips and it wont work.
If I go back to original roms it works,
If I go to original roms and leave in SRAM it works, so I think SRAM is good.

Any help is appreciated.
There's nothing wrong with his ROM images. What are you using for a NVRAM?
 
There's nothing wrong with his ROM images. What are you using for a NVRAM?
Hi Matt
I've tried 2x dallas 1220 and 1x M48Z02 ZEROPOWER SRAM and get same results. It does have original shit sockets on pcb so I may try dual wipe this weekend.

Also played with voltage at sram. Took it right to 5.00 and went as high as 5.2. No difference.

I think the sram is good as I can leave sram in and boot up with original 1B and 1C and it works as normal ram.

Also I have tried to burn and reburn the 2764 numerous times without erasing and no change.

I'm using topmax2 burner but some of these 2764s I've got are pretty trashed.

Any thoughts?
 
Are you saying the game doesn't boot when you put the new EPROMs in? Or is it just not saving scores?
Wont boot. Goes to a black screen with a white solid square (almost like pacman board when character roms arent recognized, but larger). No sounds, no response to joystick, reset on PCB, service switch. I also tried the P1 Start+ P2 Start + P1 Speedup to "reset" the highscore table in service mode, made no difference.

Currently I also have both banks of dips all set to off, if that makes a difference.

I am leaning towards the shit sockets are lined up perfectly with the original eproms, and when I try to insert new ones they arent making contact as well, and think that socketing may help.
Sounds reasonable?
 
I would question the EPROM burn. What do mean by them being "trashed"? Are the legs all bent up and dirty? Check the speed also. Some of the early 2764's were pretty slow (like 450 ns).
 
I would question the EPROM burn. What do mean by them being "trashed"? Are the legs all bent up and dirty? Check the speed also. Some of the early 2764's were pretty slow (like 450 ns).
Roger that. Will test and report back Sunday. Trashed meaning came out of poker machine and o have no idea how can can scratch up the faces so much. Legs are decent and clean. Will check speed. @mhcapps from arcadechips.com is bringing me a tube of 2764s today when we meet up.
 
Roger that. Will test and report back Sunday. Trashed meaning came out of poker machine and o have no idea how can can scratch up the faces so much. Legs are decent and clean. Will check speed. @mhcapps from arcadechips.com is bringing me a tube of 2764s today when we meet up.

Got brand new tube of TMS2764 from @mhcapps, burned roms, installed -> SAME PROBLEM.

So I went with my original idea, popped off the black plastic supports from original shitty midway sockets, put eproms down on exposed pins, fired right up.
Played a game, ran up a Highscore, played a second game, cut power after level 1 on second game, rebooted, and HS is saved.

Will remove and replace original sockets with new dual wipe tomorrow and call this one done.

Thanks @mattosborn for your help. Will then wire P2 start button to service switch for poorman "freeplay" and HSS kit.
 
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