Demolition Derby stuck at test screen

Bullwinkle

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I've been working on this one for a while, it's my UR 2Player Demolition Derby. Finally got my G07 rebuilt and working(some of you may remember..this was the monitor with the flyback that exploded on me...see pic of flyback that was removed below) so it's on to the boards. My original set, I screwed up by plugging in the power connector on the left side with the pins offset by one position ...a truly maddening evening that was (now it seems to be in a perpetual "reboot", flickers the test screen on..then off..then on ..then off)...

so I picked up a 2nd set that was a "working pull" years ago. I plug it in and the test screen comes up...and sticks there. I've checked the cables between boards and they tone out fine. could this (or the other boardset) be a processor issue or an eprom issue? Anyone have any ideas on where I should start looking? (on either boardset?)

Thanks,

-Tom
 

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Have you checked inside the coin door to make sure that there isn't a test switch that is on?

Checked to make sure all your voltages are what they should be?
 
I actually have the test switch leads snipped at the moment, so the only way to enter test mode is to tie them together. I did check voltages coming out of the ps, but not at the board. I'll check the power at the board.
 
Assuming voltages are all good and nothing funky is going on with your wiring, run the boardset without the SSIO board attached. If it comes up past the test screen, it's the SSIO board...and could be one of several issues. If it's still acting goofy, reconnect the SSIO board and try replacing the Z80CTC on the CPU board.

Dave
 
Daviea... Good call... disconnected the SSIO board and got the following screen (albeit upsidedown..it works)... cant start a game but I'll assume that is because I need the SSIO board to do it. So now to diagnose the SSIO... i do have the other one, but the previous board set does something funky too. Any suggestions on what to look for on the SSIO?
 

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Narrowed it down to SSIO?

Reconnect SSIO to main boardset.
Disconnect ALL of the wire harness connectors attached to the SSIO
All OK? Look into wire harness troubles.

Not OK and still giving you trouble:
- Check dip switches first. Turn all to OFF position.
- I would then suspect the Z80 on the SSIO board.
- Next, the two AY-3-8910's
- Still giving you trouble? double check that the crystal isn't broken off or any pins on underside of board touching each other. (physical damage, etc).
- last, but not least, check/replace the ribbon cables.

I think that covers pretty much every SSIO problem I've ever had with a Demo Derby.

Tron, Tapper, Spy Hunter, DOT, etc... totally different set of solutions. LOL

Good luck!!

Dave

Daviea... Good call... disconnected the SSIO board and got the following screen (albeit upsidedown..it works)... cant start a game but I'll assume that is because I need the SSIO board to do it. So now to diagnose the SSIO... i do have the other one, but the previous board set does something funky too. Any suggestions on what to look for on the SSIO?
 
Daviea, cool..thanks for the troubleshooting list. Just one thing, one of the troubleshooting steps calls for replacing the z80 on the SSIO board. My SSIO boards do not have a z80 processor on them. This is assuming I'm correct in calling the sound I/O board the SSIO

SSIO board is on top of stack
CPU board is middle of stack (this is where the z80 is)
video board bottom of stack


Also, I'm completely missing where the two AY-3-8910's are located. I'll keep looking but havent found them on the SSIO board as of yet.

thanks

-Tom


.
 
If yours are not on the board, skip those and focus on the other steps. I have seen Demo Derby's WITH those parts and WITHOUT those parts (Z80 and AY-3-8910) - they're all large 40 pin chips.

You are correct. SSIO is on top of stack. :)

Dave

EDIT: If you do happen to have a SSIO that requires the Z80/8910's, you might want to pop some in just to make sure. It can't hurt the board, just make sure they're plugged in correctly (not backwards). CPU goes into location 12A and 8910's into locations 6F & 7F. Good luck!!


Daviea, cool..thanks for the troubleshooting list. Just one thing, one of the troubleshooting steps calls for replacing the z80 on the SSIO board. My SSIO boards do not have a z80 processor on them. This is assuming I'm correct into calling the sound I/O board the SSIO

SSIO board is on top of stack
CPU board is middle of stack (this is where the z80 is)
video board bottom of stack


Also, I'm completely missing where the two AY-3-8910's are located. I'll keep looking but havent found them on the SSIO board as of yet.

thanks

-Tom


.
 
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OK..i see the sockets for them, but they're not populated. so I'll move along :)

I have a few spare interconnect cables I can try, we'll go there first.

Thanks.

-Tom

PS> are SSIO boards generic? can I grab one if I need to from another gameboard set?
 
Some people will say that there are only two versions of the SSIO: With Panning and Without Panning. Incorrect. There are exactly five different versions, each very specific for it's use.

Luckily, some of them are so rare, it's unlikely that it will be an issue. Many of the SSIO boards will directly interchange with each other, minus ROMs and panning/no-panning.

If you can find a board with the same part number number (disregard the very last 4 digits A000, F000, G000, etc) you should be OK. Make sure, though, that you pull ROMs and set all dip switches to OFF.

Dave
 
Some people will say that there are only two versions of the SSIO: With Panning and Without Panning. Incorrect. There are exactly five different versions, each very specific for it's use.

Luckily, some of them are so rare, it's unlikely that it will be an issue. Many of the SSIO boards will directly interchange with each other, minus ROMs and panning/no-panning.

If you can find a board with the same part number number (disregard the very last 4 digits A000, F000, G000, etc) you should be OK. Make sure, though, that you pull ROMs and set all dip switches to OFF.

Dave

OK... digging up an old thread because I'm finally able to get to my demo derby again (was packed away while I remodeled the gameroom.

So I've got a 3rd SSIO (populated with z80 and two AY-3-8910s) .tried it with the chips in place, removed them and tried again. Same stuff. With the SSIO attached to the harnesses, I get the test screen. If I disconnect the the harness at J4 on the SSIO, i get the game to come up, but no control or sound. At first glance, it looks like an SSIO problem, but I think it might be something from the CPU board.

Looking at the schematics (and I'm not expert that's for certain), the pinout for J4 on the CPU board (which connects to J2 of the SSIO) shows +12v at pins 11 & 12, yet I'm not getting voltage a cross those pins. Does the voltage come to or from the SSIO over those pins. The way I read it, it should come from the CPU board into the SSIO...and if that's the case, my problem is on the CPU board.

Any ideas on what I should be looking at now?

thanks

-tom


UPDATE:

Got it working as far as game play goes, video, controls & test mode... still no sound. am continuing to diagnose.
 
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