QBert Power Supply Issue

rockinganker

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Hello,

I bought a power supply rebuild kit from Riptor and installed it. I now have a working supply that puts out a nice +5 volts. My problem now is, once I hook-up the connectors to the output, the voltage drops to 4.1 volts. I'm not sure what would cause this...any help?

I have checked the sound board to make sure everything is working and I do get the "Hello, I'm On" sound on start-up if the main pcb is not connected. Once I connect the pcb all I get is static. I'm guessing that's from the main board not booting, I could be wrong though.

The two resistors located at R13 and R14 get very hot but still everything checks out, could I have mounted them backwards?

Any help would be awesome.

Thanks
 
Hello,

I bought a power supply rebuild kit from Riptor and installed it. I now have a working supply that puts out a nice +5 volts. My problem now is, once I hook-up the connectors to the output, the voltage drops to 4.1 volts. I'm not sure what would cause this...any help?

I have checked the sound board to make sure everything is working and I do get the "Hello, I'm On" sound on start-up if the main pcb is not connected. Once I connect the pcb all I get is static. I'm guessing that's from the main board not booting, I could be wrong though.

The two resistors located at R13 and R14 get very hot but still everything checks out, could I have mounted them backwards?

Any help would be awesome.

Thanks



Were you able to play the game before your installed the rebuild kit? Like was the mobo ok?
 
R13 & R14 run hot, this is normal. There is no polarity on a resistor so thats not a problem either.
Did you replace the pot when you installed the kit? If so, did you adjust it (+5v) after the rebuild?
Sounds like your 30v is working fine, it powers the sound board and knocker. I wouldnt worry about the sounds until you get the game board up and running. If I recall you normally get the "hello im turned on" whether the main pcb is plugged in or not. In fact, it will usually say that even on a partially working sound board as long as you have 30v and a good amp.
I would suggest unplugging the sound board for now until you get the main board booting. Check all the solder joints on the filter board and reflow them if they are cracked.
When adjusting the +5 I reccomend measuring on the main pcb because you typically loose about .25v through the harness and qbert will do some funky stuff if the voltage is low. Around 5.05v on the main board is what you should shoot for.
 
Thanks for the advice. I installed everything in the kit including the pot. The problem is, I can't adjust the pot high enough to get 5 volts at the board. I have already reflowed all the filter board joints as well as all the joints on the power supply.

I'll unplug the sound board and see fi I can get enough voltage to the main board.
 
Qbert Power

I could be that thre is a short on the main board that is dragging the voltage down. Usually a short like this will generate heat in the shorted part.
 
Yeah, after posting last night I checked some things out. Turns out that once the main board is connected, the voltage drops to 1.5 volts. So, there is a short some where...just need to find it.

I've removed the battery and installed the jumper, I've also replaced the two caps at c25 and c27. C25 looked to be installed backwards meaning, the neg side of the cap was on the positive side of the board. Not sure why, but it looked to be factory.

Anyway, the high score mod showed the cap installed in the right direction.

Hoping something happens :)
 
Some revisions of the board will have one of the caps in backwards. If you look at the bottom of the board there will be a trace that is cut on these.
If you installed a lithium battery, did you install a diode and remove the resistor?
 
How do the connectors look? Do any look burnt? My Krull had a few burnt connectors that were causing problems, and I believe uses the same power supply as Q-bert.
 
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