Forum Topic

Baby PAC eprom

By xbdrabbitx

1 year ago


  • 29 posts
  • 6 Pinsiders participating
  • Latest reply 1 year ago by vec-tor
  • No one calls this topic a favorite


Search this topic for posts matching certain words or written by a specific Pinsider. Or both!

Linked Games

Topic Gallery

There have been 3 images uploaded to this topic. (View topic image gallery).

IMG_6139 (resized).JPG
IMG_6138 (resized).JPG
IMG_6100 (resized).JPG

#1 1 year ago

I may have a damaged eprom on my baby PAC vidiot board. What do I do? Can I acquire new ones? Can I burn a new rom image? This is totally new to me.

IMG_6100 (resized).JPG

#2 1 year ago

I had a baby PAC the eproms are easy to obtain
Depends on how many games your going to get but I purchased my own writer and eraser years ago cheap good investment. Depends on how fast you want it but somebody I used eBay can get it to you fast. EPROM girl on eBay just search Simpsons EPROM and send her a question she is fast and reasonable

#3 1 year ago

Thanks for the info. If I did buy a writer, where would I find the roms? I assume they are different for each chip?
Also, I found this on the back side of the vdp chip. Is this normal, or did someone do a hack fix?

IMG_6138 (resized).JPG

IMG_6139 (resized).JPG

#4 1 year ago
Quoted from xbdrabbitx:

Thanks for the info. If I did buy a writer, where would I find the roms? I assume they are different for each chip?

Yes, each ROM has its own program code. You should be able to find the ROM images on IPDB in the ROM zip file.

#5 1 year ago

John Wart Jr frequents the forums here, and he can burn new ones.

If you want to do it on your own, you'll need to determine how your board is jumpered and which EPROMs it is configured to accept, find that EPROM (or rejumper your board to accept more common ones), and get an EPROM burner and eraser. link » Prg 113 Gq 4x V4 Gq 4x4 Trueusb Programmer Eprom Uv Eraser Adp 054 Adapter

#6 1 year ago
Quoted from xbdrabbitx:

Also, I found this on the back side of the vdp chip. Is this normal, or did someone do a hack fix?

I've seen a few vidiot boards, but don't remember seeing that add-on on the back. I'd leave it alone if it's not causing problems.

#7 1 year ago

Okay thanks for all the good feedback. Let me tell you what's going on. When I got the game, it didn't work. The screen came up blank and red. I was able to use the video test to get the screen to look okay. But the game didn't start. I popped out the eprom that the FAQ says is causing an issue. I cleaned the contacts and put it back in. Fired it up and the game played. But looked goofy. So I pulled the other EPROMs one at a time to clean them thinking maybe it would clean up the image. And when I did that, I bent one of the legs on the eprom at u10. I carefully bent the leg back and added a touch of solder on it to mend it. Just in case it was cracked. I put her back in, and the game now gets stuck after the 8th blink of the light. Which the FAQ states is the vdp chip. I can't help but kick myself hard to fucking around and not being more careful. So I ordered a new vdp chip and I'll replace it and hope for the best. If that doesn't work, and still gets stuck, I'll replace the socket. Although.. I checked continuity between the top of the chip to the solder joint at the bottom of board. Not sure if that's the proper way to see if the socket is working as it should... what do you guys think?

#8 1 year ago

I did pull the vdp chip and cleaned those legs also. That's why I'm looking st the back and wondering if that resistor/cap install is proper. And if that could be causing my game to not clear the vdp check.

#9 1 year ago

8th Flash.
The 6809 CPU chip at U8 attempts to test the PIA chip (6821) at U7. If the PIA is good, the eighth LED flash is shown. If there is no eighth LED flash, the PIA at U7 is bad.

#10 1 year ago

Yes, as stated above, I get the 8th flash.. but not the 9th.
"The 6809 CPU chip at U8 attempts to test the VDP (Video Display Processor, which is the TMS9928 at U16). If there is no ninth LED flash, the TMS9928 at U16 is bad."

#11 1 year ago

Does the 8th flash get stuck on, or does it turn off?

#12 1 year ago

it flashes and turns off. i get scrambling items on screen.

#13 1 year ago
Quoted from xbdrabbitx:

it flashes and turns off. i get scrambling items on screen.

Alright, next you can take a look at the back of the board and check for cracked solder joins on each leg of the u16 socket.

Next, try continuity testing for each leg.

Put on probe on each leg near the top of the chip, and the other probe on the corresponding socket pin on the back of the board.

Also, put the board up to a light and see if you can spot any broken traces on either side of the board.

#14 1 year ago

I'll take a look again. I did check for continuity and it checked good. I put a light to the board and looked at traces, they look good too. I'll look for cracked joints. I'll take my meter and check continuity for some traces too just to be sure.

#16 1 year ago
Quoted from xbdrabbitx:

Thanks for the info. If I did buy a writer, where would I find the roms? I assume they are different for each chip?
Also, I found this on the back side of the vdp chip. Is this normal, or did someone do a hack fix?

Ok, I checked the vidiot boards I have and they all have the resistor and cap added to the back of the board, so I'm assuming that's a factory addition.

#17 1 year ago

Forceflow thanks for all your help. I'm very glad you found that was a factory addition. I looked really hard at the schematics, and it looked as if it was supposed to be there but I'm no electrical engineer. I did order that chip from twistyarcade. Thanks

#18 1 year ago

The VDP chip overheats during operation and fries itself. Add a heatsink to the new one after installing it.

#19 1 year ago

think the VDP chip would quit working after 2 minutes of being on?

#20 1 year ago

I've heard the process is slow, from months to years. Like the issue with the Nintendo Wii and standby mode overheating that plagued the consoles. People didn't start noticing the damage to the video chip until much later in production.

#21 1 year ago

okay. well lets assume this should fix my current issue. You guys have a link to a heat sink recommendation?

#22 1 year ago

I'd look for a DIP heatsink and thermal glue or a thermal paste pad to secure it.

#23 1 year ago

Ok. Maybe I'm just a little slow here.. someone please help me count these stupid flashes. Am I doing something wrong? How many flashes do you see? Does the first flash even count?? Help! Forceflow?

» YouTube video

#24 1 year ago

Looks like a ram issue.

#25 1 year ago

Yep, seems like it could be a RAM issue. Take a look at the troubleshooting info under flash #10.

It could be connectivity between chip legs and the sockets, cracked solder joints on the socket legs, chip leg corrosion, bad socket contacts, cut/damaged trace issues, or simply one or more bad RAM chips.

#26 1 year ago

So you guys saw how many flashes? 9?

#27 1 year ago

Those ram chips are cheap, I can pick all 8 up no problem.

1 week later
#28 1 year ago

Okay. I replaced all the ram chips on the board. And reseated all EPROMs again. After this, the game boots 100% and had no issues with gameplay. Working on recapping everything now. Just finished the monitor and did my adjustments. Boy is it a night and day difference! Thanks for all your help thus far.

#29 1 year ago


Promoted items from the Pinside Marketplace
From: $ 16.95
From: $ 129.95
€ 3.95
Flipper Parts
1,200 (OBO)
Machine - For Sale
Hurst, TX
From: $ 119.95
From: $ 29.95
$ 22.00
Cabinet - Sound/Speakers
ModFather Pinball Mods
$ 48.00
Cabinet - Other
ModFather Pinball Mods
From: $ 9.99
Matt's Basement Arcade
$ 5,699.00
$ 15.00
Playfield - Decals
$ 6.00
$ 229.99
Lighting - Other
Lighted Pinball Mods
$ 99.95
Cabinet Parts
Merf's Pins
$ 10.00
Playfield - Toys/Add-ons
ModFather Pinball Mods
$ 45.00
Cabinet - Other


Note: This is an old thread. The last post was made to it 478 days ago. Resurrecting old threads is not necessarily a bad thing, if you think the topic is still relevant and/or your post is beneficial to it (e.g. following up on something). In other cases, it might be better to create a new topic.

Wanna join the discussion? Sign up for a Pinside account, or log in if you already have an account.

Hey there! Got a moment?

Great to see you're enjoying Pinside! Did you know Pinside is able to run thanks to donations from our visitors? Please donate to Pinside, support the site and get anext to your username to show for it! Donate to Pinside