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quick q on multikit w/o key writing

Have you checked for bent or broken pins between the 2 boards? That's usually what causes these kinds of faults
 
Also, as you're running them outside of the case, try pressing down on the 2 customs on the B board on the right side (underneath the mask ROM area)

These are address and data generation customs for the sprites, and I have seen boards where these fail or need a reflow
 
So I had an interesting night with this board...

Trying to learn things as I move along with this jail-bar issue. I see another awesome forum member mapped out the wiring on the B board so I started using the continuity feature on my multi-meter to test between CN2 and 1927. My eyes started to hurt after trying 6 pins and there are 120 per graphic chip! I gave up pretty quick. But see how this can be useful in the future.

Now for the scary part, I've been pressing lightly here and there and squeezing the boards to try and get these damn bars to go away but I guess I never pressed on DL-1927 or 2027 before. When I pressed LIGHTLY on both of the customs the board shorted out or something! Knocked out my supergun and power supply. The power supply was making a hissing sound till I unplugged it (is that a cap gone bad I assume?). This can't be normal? I must have agitated something that maybe is the root cause of all this?

I freaked out and calmly went in the kitchen and started sipping some 10 year rye.

I came back and plugged in just the power supply and no hissing and the voltages read ok. So then I tried it with just the supergun and voltages were still ok and thankfully my supergun wasn't dead. I bought a backup power supply since they are only like $20. It isn't hissing anymore but not sure if it is good to keep using it. I also then tried the board just to see if it was toast. Amazingly it still works and loads up to the jail-bars so I guess nothing is worse now than before but I don't want to touch this thing anymore lol.

I was going to disassemble the kit next and look at the GFX roms to see if those pins have an issue but not sure it's worth trying anything else with this after what happened.


I think I am going to look for another US/Japan B board at this point. Pretty sure the A board and multi-kit are fine. Once my skills are better I can revisit this.
 
If you're using one of the cheap Chinese PSUs, don't. They are a bad day waiting to happen. Please don't risk hurting yourself with those cheap nasty PSUs, never mind the risk of damage to the board you're working on.

Get a Suzo Happ arcade PSU, Mean Well bench PSU or a non rubbish (something 80+ rated at least) ATX PSU (ATX is the safest option)

Electricity is no joke, at the very least a shock will hurt like hell.

Those 2 customs are exactly where I would be looking of the fault is definitely on the B board
 
I am using the Suzo Happ. My backup is the Mean Well RGB recommended on his FAQ. The only cheap Chinese thing I bought is that EPROM eraser that does the job :) Everything else I've been following what I read from these forums.

So it is definitely those 2 customs then? Any advice on what I should do next? I was thinking of trying that continuity test on all the pins but thats 240 pins! So I don't think I can do that without losing my mind.

The fact that the board crapped out like that when I pressed on them makes me kind of nervous to power it up again.
 
It's not definitely those 2 customs, just that's where I'd be looking

They may be bad - just if you have jailbars and the A is definitely good it's either a bad trace to one of the line between the 2 boards, or one of those customs is loose/bad

I would maybe put it aside for another day as you said, I do this regularly and I've ended up fixing some stuff months/years later :)
 
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