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WPC No power to CPU

orchid

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Joined
Apr 18, 2012
Messages
57
A worrying problem has developed with my Judge Dredd. I returned from a weekend away to find that it won't boot. My housemate had been playing it and reports that it suddenly reset/turned off, and then wouldn't turn back on. When I came to look at it a couple of days later, the machine seems to boot, but the DMD is scrambled.

Looking inside, none of the CPU LEDs are lighting up. I have tested all the fuses (in place) and they're fine. I have removing everything apart from the power ribbon (J210) and it remains the same.

Any thoughts on where to go next with diagnosis?
 
Have you tested for voltage on the CPU board? I suspect the 5v is missing (or the capacitor has failed) but the next step is to see if that's the case.
 
Thanks - I haven't. Which pin should I test for that sorry?
 
Ace, thanks. No, no power there! Reading .256, which sounds pretty well out of normal operating bounds. Pins 6/7 are reading 12V fine though.
 
Also just checked and the 5V seems to be missing back to TP2, so I guess that this is the issue (and TP1 is reading close to 15V incidentally). Any thoughts on further checks?
 
Had similar problem with my Tom for weeks (mainly resets).... Have just cleaned pins and re-seated connectors J104, J102 & J101 on power driver board tonight and appears to have solved it. Beforehand, mine was dead as a dodo with scrambled display and no lights on CPU board, just like yours. Worth trying...!
 
Thanks JMP - unfortunately reseating those connectors hasn't fixed it for me. So, checking the +5v section of the power board. I think I should be following this backwards? So, first up - how do I test the LM323K? Google isn't proving very helpful...
 
Can't help you there but just replied via the Yahoo group by saying I would still try REPLACING connectors for J114, J101 & J102 on both the board and wire side (or at least the wire side if you don't have the board soldering skills).

I had two months of resetting problems with my ToM, throwing me off in all directions and it was one of these connectors all the time as Andy N. said it likely would be.

Did you try re-seating the actual wires into the connector? You can buy the push tool to do it properly.
 
Thanks JMP - unfortunately reseating those connectors hasn't fixed it for me. So, checking the +5v section of the power board. I think I should be following this backwards? So, first up - how do I test the LM323K? Google isn't proving very helpful...

Unusual for the LM323k to go (not impossible though) test the bridge, check the cap and more simply - check the fuse!
 
By f*cking jove JMP, you were right! After getting annoyed and leaving the poor old Judge untouched for a month, I came back to this thread and trie again, and it turned out that while testing through the J101 connector (by metering each of the connections above the crimp) I must've pushed a loose wire back in, and lo & behold it reset and looks like it's working.

Ordering a new 7-pin connector now to replace it with, then I'll give it a test game. It's incredible how simple these things can be sometimes! Thanks for all your help everyone. Back to pinball.
 
Glad to hear it. :) If occurs again after changing your wired connector, get the board side connector done too if possible.
 
Just to check - is the replacement for J101 a 0.156 crimp housing 7 way?
 
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