Qbert No +5

Todd31

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Donor 2011
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Ok, tested all the fuses. Swapped power supply boards with known good. Swapped filter boards with known good. The light is completely off with no voltage at all going to the +5. When the game is turned on the monitor gets power, the marquee lights of course and all the other voltage lights come on on the power supply other than the +5 volts.

What are some of the common issues for something like this?

When this started to fail the +5 faded out over I would say days, it wasn't a fast failure. The +5 failed so I rebuilt the ps board. The +5 was still low at around 4.8v max but the game ran. Then, it started taking multiple power off and ons to get the game to come up. Then the game sat for a month or so and the +5 is now non existent. I bought a rebuilt supply online that was tested working and also acquired a tested working filter board.

Any help would be appreciated.

Thanks,
Todd
 
Ahh... Gottlieb power supplies. A subject near and dear to my heart.

When you talk about rebuilding the power supply, you're referring to the A3 board, right?

Have you checked out the transformer ass'y? It has a bridge rectifier and a ginormous 50,000uF filter cap that sound like prime suspects. (I assume you've checked fuse F4 already.) These provide the 11.5VDC unregulated for the the A3 board to turn into nice regulated 5VDC. Check pins 1 & 2 on A3 P1 (relative to GNDs on pins 3 & 4 of the same connector). Low DC level (under 10 or 11V, mebbe) or high AC content are causes for concern.
 
Ok, tested all the fuses. Swapped power supply boards with known good. Swapped filter boards with known good. The light is completely off with no voltage at all going to the +5. When the game is turned on the monitor gets power, the marquee lights of course and all the other voltage lights come on on the power supply other than the +5 volts.

What are some of the common issues for something like this?

When this started to fail the +5 faded out over I would say days, it wasn't a fast failure. The +5 failed so I rebuilt the ps board. The +5 was still low at around 4.8v max but the game ran. Then, it started taking multiple power off and ons to get the game to come up. Then the game sat for a month or so and the +5 is now non existent. I bought a rebuilt supply online that was tested working and also acquired a tested working filter board.

Any help would be appreciated.

Thanks,
Todd
How's the big blue cap on your transformer block? Have you tested it? I replaced mine with a new one from Bob. That *could* be your problem, but then again, with Q*bert it could be any number of things.
 
Yes, I was referring to A3. I look forward to getting to the bottom of the issue. Thanks for all the help so far guys.

Todd
 
i've had +5 fade in and out before on mine. the fuse clip was loose and making intermittent contact on the transformer assembly.
 
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