space duel ar II board problems

tron guy

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so I rebuilt the bad board I had. It was putting out +8.6 on the +5.
When I replaced the board with a known working one I got my +5 and my game worked.

so I rebuilt the bad board, and I am still getting +8.6. I turned what I believe to be the power adjustment pot on the board and simply no change. turning it all the way one direction and measuring to +8.6 and all the way the other direction and measuring +8.6.

What's next? Replace that pot?

chuck the board with the new parts, lol.
 
What parts did you change on it? I think you'll find you still have a bad transistor...

I changed all the caps. I changed the center transistor and a side transistor thatmounts to the big black hunk in the middle.
 
I doubt very seriously that changing the pot is going to help at all.

I have a similar issue with an ARIII I'm working on. The +5 was running at +7.3 and the pot adjustments did nothing. I changed out all the caps, all the transistors, the LM305, and the pot (even though the old one measured fine) and I still had the same problem. I found one resistor that was measuring as open, and changing it got it down to +6.8, but I haven't found any other problems yet.

Part of my problem may have to do with the Power brick putting out +14.8 where I should be getting +10.6, but a replacement of the Big Blue(s) and the rectifier did nothing to affect it...
 
Mod brings up a good point. Pull the pot off the board and measure it to see if it is still good first.

Mod: I have read up on your Paperboy A/R III issue, and have been waiting until some RAM chips come in. I will then take some readings to see what I get, compared to what you are getting. Was also going to verify the power brick / big blue's (2)wiring for you too. Damn Paperboy is too heavy for me to move, and I will only have one shot at it once the wife moves it for me.
 
so I rebuilt the bad board I had. It was putting out +8.6 on the +5.
When I replaced the board with a known working one I got my +5 and my game worked.

so I rebuilt the bad board, and I am still getting +8.6. I turned what I believe to be the power adjustment pot on the board and simply no change. turning it all the way one direction and measuring to +8.6 and all the way the other direction and measuring +8.6.

What's next? Replace that pot?

chuck the board with the new parts, lol.

I agree with the others that said the pot probably isn't your problem. The 2N3055 is bad (I know you replaced it...maybe a bad one out of the box), you have a broken trace associated with the 2N3055, or less likely (but possible)...the LM305 is bad.

Oh yeah, ohm out the big power resistors/check them for cracked solder joints.
Edward
 
here are some pics of the board after the cap kit/rebuild
 

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I would replace the LM305 and re-test. If I am reading the data sheet correctly, you would get about 9vdc if the LM305 failed.
 
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lm305 changed

no change. This board is virtually completely rebuilt. Reflowed so much solder it's unbeleivable.

No matter this fucked up board goes in the "other space duel" lol
but what a waste of money and time. So far that is. :O)
 
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