Repair logs

I recently bought a job lot of 16 faulty boards plus I have all my other faulty boards I've collected over the years scattered every where.

So I've been in a hurry to repair boards and get them sold just to make some space, because of this I haven't really been thinking about logging the repairs or taking pictures.

I have covered as much as I can remember but that's why there's no pictures this time.

Shinobi
No sound apart from 'mission one' when you start a game otherwise completely silent. A note on the board said 'probably YM2151' but looking at it on the scope all pins looked very active, the near by YM3012 on the other hand had four dead pins. Piggy backing a pulled 3012 from a scrap board brought all sounds back.

Street Fighter 2 World Warrior (Bootleg)
Lots of missing sounds, sounds playing randomly, noise / static and missing the colour red.
Looking on the bottom of the board there were some pins that looked like they had little to no solder on them. After soldering them properly red returned. As for the sound I suspected the yamaha chips at first as these bootlegs use fake chips. Turned out to be the surface mount OKI 6295 chip, I took one from a scrap CPS1 board.

CPS1 Motherboard
Game running but screen is blue and nothing is visible.
All four 6116 palette rams near the edge connector bad. Depending on the board some times it's 2x 6264 rather than 4x 6116.

CPS1 Motherboard
Board would always lose sound after a few minutes.
This one was a real bastard to find, I thought it was going to be a thermal problem and something was failing as it heated up. I thought the most likely candidate would be the z80 cpu as capcom fitted a standard z80 instead of a z80a. Then I tried replacing the amp, still no difference. I recapped the entire sound section still no change. I was about to give up but thought what the hell and replaced the z80 crystal even though I've never had a crystal fail on me before apart from ones that were physically damaged. To my surprise this actually fixed it.

Commando (Capcom)
Bad background graphics.
The only fujitsu ttl on the top board a 74LS30 if I remember correctly, replaced and problem fixed.

There have been several other repairs but simple trace repairs and ram replacements.

Gun Smoke (Bootleg) repair

I bought this bootleg Gun Smoke board years ago but a colour prom was missing and as I had no way to burn another it has pretty much sat waiting for a prom ever since.

Time to deploy my new favorite toy that I picked up from ebay a couple of months ago.

Stag System 3000 (cira 1991)

This beast of a programmer can program many chips but most importantly for this repair it can do bipolar proms.

I usually use it on an old laptop in dos connected by serial cable but as I had an original Gun Smoke pcb as well I decided to copy the original proms directly rather than try and find the correct files in mame. Turn the key and you're in standalone mode, copy the content of the original prom and burn it to a new blank one which took a total of about 8 seconds.

When the prom was missing the screen was all red (which I forgot to photograph) but just think of a virtualboy game.

After installing the new prom the game looked a lot better but there was no green, checked the green pin at the edge connector with a meter and sure enough 0v. Traced it back to the prom next to the new one, pin 12 had internally shorted to pin 8 (ground).

Bad prom removed.

I did the same as before to replace the missing prom by simply copying the one from my original board and burning it to a new old stock 82S129.

Green restored, repair complete.