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Astro Blaster Z-80 Arcade Machine Help

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bluemanop:
Does anyone have much experience with repairing a full size Astro Blaster arcade machine? The machine currently posts to a completely blue screen and the speaker is making a low roar. The speaker in the unit was being worked on when the machine went dead.

I have clean power, I believe, a good monitor but I believe the main CPU board maybe dead. I believe this to be the case due to the red light CPU halt light on the CPU card being lit. The manual states that it could be a failure with the u26-u29 chips, C10615 ,which I believe to be memory chips or maybe even the Z-80a processor 8400W2N. Could there be any other problems that could have fried these chips like a bad sound card or would replacing any and all of these parts fix the problem?

Any help diagnosing / troubleshooting / fixing would be appreciated.
 ???

D_Zoot:
I assume the board does not boot at all,  no activity on the screen, no test mode available or working etc...

If you are sure that your voltages are spot on......

1) Carefully inspect the board for cracked solder joints, damaged traces or missing/damaged components.

2) Reseat any header connectors, edge connectors, ribbon cables or pin connectors (I'm not familiar with this specific board, so I don't know what it has)

2) Remove any socketed chips and reinstall.

If everything above checks ok, then it goes like this:

There are alot of things that can prevent a game board from booting. Bad cpu, failed rom, failed memory, loss of clock, failed reset line....    Further troubleshooting requires an O-Scope or at least a logic probe.  It might be a good idea to have somebody familiar with board repair to have a look at it.

I wouldn't suggest just replacing any chips without some idea of what was going wrong with the board.   It's easy to run yourself around in circles just trying to throw chips at it.

Regards,
D

bluemanop:
Thanks for responding D-Zoot,

You are correct, the board should post to a memory test. It does not do anything but display a blank, blue screen. No game post at all.

I believe the power supply is still good but I have not hooked a multi-meter to the power supply as of yet. I will observe the manual for the proper power output to the power supply and see what I find.

I reseated all the cables & edge connectors but that did not yield any results. I suspect the main board because of the red error light on the CPU board. I thought to remove the chips and reseat them but I did not have a small screw driver on me or IC puller. I will do this the next time I am in front of the machine.

I was on the same page as you, a bad CPU (z80a) processor or memory chip. Not sure about a failed ROM or know what loss of clock is or failed reset line. I was thinking that the unit would have posted with something it had a good proc or mem chips. Manual stated something to the affect that it would note bad ROM chips after the initial memory post. I will definitely keep it in mind.

I was afraid someone would say logic probe or oscilloscope, all of which I don't have. I have considered visiting this guy's shop where I know he has these tools but he is somewhat of a miser and generally not open to visitors.

Would you have any good links to replacement arcade parts (spare processors and/or memory chips, etc.)? This is what I have read of the CPU board.
-----
CPU
Zilog Z-80A
8400W2N A
8030 PS
-----
Memory (No name just a logo that looks like an "S")
8047
C10615

I'm an old video game arcade nut and this is my first dabble into repair. Although I am not a complete rook in electronics it has been over 15 years since I have really done anything in this area aside from building PCs. I hope this experience with revive an old passion. I look forward to hearing some more input.

Thanks again.
 :D

D_Zoot:

--- Quote ---Not sure about a failed ROM or know what loss of clock is or failed reset line.
--- End quote ---

Okie then,

D_Zoot:
Here's two case studies that you might find interesting.

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