Hi
I'm looking to swap out Q5, a 2N6087, on a Williams sys 6 PSB.
Virtually everything else on the PSB has been replaced but I'm getting random CPU crashes after about 20 mins or so of attract mode and Q5 is getting very hot.
I want to replace it just to rule it out.
Can't seem to find one anywhere. What alternatives are available?
PMD10K40 is also a high current Darlington pair transistor -- also an alternate for the 2N6057. I have no idea what an SH1275 is.
I thought System 6 machines used LM323K type regulators and the series pass transistor design (used 2N6057) didn't get used until System 7s.
If you have the series pass transistor design then it sounds more like the regulator (LM723) isn't functioning. This if often due to small caps C7 and C8 going bad. Did you replace these two?
Quoted from G-P-E:PMD10K40 is also a high current Darlington pair transistor -- also an alternate for the 2N6057. I have no idea what an SH1275 is.
I thought System 6 machines used LM323K type regulators and the series pass transistor design (used 2N6057) didn't get used until System 7s.
If you have the series pass transistor design then it sounds more like the regulator (LM723) isn't functioning. This if often due to small caps C7 and C8 going bad. Did you replace these two?
Yes I have replaced all the caps. I will try the LM323K which I also have from you 
I think I am confusing the sys 6 and sys 7 PSBs.
Quoted from G-P-E:You mentioned the transistor was getting real hot. Yes, it does get real hot normally. If abnormally hot - is the current sense resistor (R13?) also getting real hot? If so, the power supply may be overloaded and shutting down.
The heat sink was too hot to touch which didn't seem right.
I don't know if R13 was also hot unfortunately.
Quoted from Zigzagzag:Unfortunately shipping from US is severely delayed these days.
Post office is definitely FUBAR right now. Fortunately, Most orders to EU are not taking that long but there are a few winners.
Last order to Netherlands took 3 months and 1 day to arrive - one day after insurance claim period. Not sure what is happening but the delay is occurring between the Chicago exit of country and the destination country's port of entry. Getting put on wrong plane maybe? Does not only affect EU, last shipment to Japan left country through Chicago - showed up in Cincinnati airport one month later.
I unplugged the displays and soundboard but still get the crashing in attract mode. None of the chips seem excessively hot on CPU and driver boards. IC1 is a little warm but not excessively.
I have replaced interboard connectors and swapped round the socketed 6821s on the driver board without any joy.
I will borrow an IR thermometer from work when next in to see if that can give me any clues.
Displays draw very little current (usually the LED replacement type draw more than gas plasma ones).
Ditto with the sound board.
Your main current draw is the resistors in the lamp matrix and the lamps themselves. Try pulling the lamp fuse and measuring again.
Or do you mean 1.7 amps on the +5 line?
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