Burt6666
Well-known member
Is a 6820 the same as a 6821?
PIA Question
- Thread starter Burt6666
- Start date
Lindsey
Well-known member
Yes.
EDIT: Well... no but they're interchangeable.
EDIT: Well... no but they're interchangeable.
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Burt6666
Well-known member
Yeah..I found the answer on pinrepair.I have lots of 6820's in some old boards out of those cocktail machines.I think that may be the issue with that Phoenix machine....
Lindsey
Well-known member
If you suspect a PIA problem Leon's test ROM will be the quickest way to find it.
Alternative solution: Trade it to me
Alternative solution: Trade it to me
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Burt6666
Well-known member
How does one go about that?
Lindsey
Well-known member
1) buy logic probe
2) acquire test ROM (from me)
3) http://www.pinrepair.com/sys37/index2.htm#leon
4) trade to Lindsey who already has logic probe and test ROM
2) acquire test ROM (from me)
3) http://www.pinrepair.com/sys37/index2.htm#leon
4) trade to Lindsey who already has logic probe and test ROM
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Burt6666
Well-known member
Trade what??? I have been meaning to buy a probe,however.
Lindsey
Well-known member
How about a nice 4 player showcase machine with 32" monitor? Ready for MAME!
Seriously though... the most direct approach to troubleshooting MPU problems is to pull the MPU and driver board and go through them with a test EPROM. You could use a meter but a logic probe is a lot easier to use for stuff like this.
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Burt6666
Well-known member
Haha... wife says no.... haha !!! JK... This machine is pissing me off.I changed the bad tranisitors,the bad 7408 as well...that's what's leading me towards the PIA.
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Burt6666
Well-known member
Still have 1 locked on coil and the ball never kicks out at game start.It will kick a ball if I short it's trans to ground.IC5 PIA never gets warm at all where the other 2 do(on driver board).
Lindsey
Well-known member
Did you check the pre-driver transistor?
The PIAs are not typically socketed on those boards. With a logic probe you could check the PIA output for that solenoid with the MPU in the machine running in attract mode.
If the driver, pre-driver transistor and 7408s are good I would suspect a shorted PIA output next. You could use a meter to determine if the PIA output is stuck high or low but I would still recommend getting a logic probe.
Desoldering the PIA will be tricky. It's a lot easier to make a board worse than fix it in cases like this.
EDIT: It's also possible you've got corrupted game ROMs.
The PIAs are not typically socketed on those boards. With a logic probe you could check the PIA output for that solenoid with the MPU in the machine running in attract mode.
If the driver, pre-driver transistor and 7408s are good I would suspect a shorted PIA output next. You could use a meter to determine if the PIA output is stuck high or low but I would still recommend getting a logic probe.
Desoldering the PIA will be tricky. It's a lot easier to make a board worse than fix it in cases like this.
EDIT: It's also possible you've got corrupted game ROMs.
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Burt6666
Well-known member
Drivers,pre-drivers and 7408 have all been changed....I was going to put a socket on the board for the PIA.
Lindsey
Well-known member
Definitely do that.
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Burt6666
Well-known member
Changed the PIA...now I'm back to the all coils lock on at power up.However,the ball kickout now fires....
Lindsey
Well-known member
Ugly. Definitely time to pull the MPU and go through it. If you haven't replaced the interconnect that's a must at this point. That could very well solve your problems but I would still consider installing fresh ROM code and replacing any suspect sockets.
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Burt6666
Well-known member
This starting to get beyond my abilities...LOL.
Or maybe I'm just frustrated and cranky...time for a beer...
Or maybe I'm just frustrated and cranky...time for a beer...
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If it has never been done you need to replace the interconnect on the Driver and CPU boards.
Like Lindsey said get a copy of Leons test rom and follow the System 3-7 guides here:
http://www.pinrepair.com/sys37/index1.html
It really will take you step by step through the process. It was invaluable to me when I was rebuilding the boards in a Time Warp I had. The PIAs are hard to find nowadays but they are out there.
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Burt6666
Well-known member
Thought I'd give you guys an update....had the PIA in backwards....oops.
