data east power supply

[stangbat]

I'm not totally sure. I've measured three different transistors, one is a 1N6057 and two are 1N6059 (a higher voltage version of the 6057). With all three I got

C-E around 0.450v
C-B around 0.595v

So in my case I'm seeing higher voltages between C-B than what you are measuring. But I'm not sure if what you are measuring could be a problem.

As for the capacitors, it is hard to say for sure unless you remove the caps and measure them. Some of your values are off, but unless you removed them and measured, you can't place a whole lot of value in those reading.

Same often applies for resistors. Sometimes you'll get a wrong reading due to other paralleled resistors in the circuit, but if you remove the resistor and measure it, it will be fine.

Edit: I'd maybe try the good PS you have in your other machine and see if it works. Before doing so, double check your fuses to make sure they are the right values.

 

[Trent]

I second this. The regulator rarely fails. Just replace this cap. It will need to be replaced as some point anyway and see what happens.

Trent

I don't know where my brain has been. The most likely problem is capacitor C2, the little 100 uF 25v cap below and right of the big heat sink. This little guy gets hot from the heatsink and fails.

But you also should check the 2N6057 with the power off and use the diode test mode on your meter. You'll put one lead on the metal part of the transistor (C) and the other end on one of the two pins (B and E). You should read between .4 and .6 on your meter (it may be between 400 and 600 depending on your meter.)

Some testing info here:
http://www.elexp.com/t_test.htm
http://www.kpsec.freeuk.com/components/tran.htm

If the 6057 checks okay, then you need to check the capacitors, specifically C2.

 

[stangbat]

drwicket sent this board to me last week and I've got it going. This was an interesting one. C2 was clearly out, right off the bat I could see some remnants of electrolyte on the PCB. After removing C2, I could see that when it had taken a dump, it destroyed one of the solder pads on the PCB. Got that fixed and also replaced C1 since it looked a little bulged. I also replaced C7 since it is so close to the heatsink.

I did some other housekeeping work, installed the PS to test, and it still wasn't working. So I decided it was then time to check the 2N6057 at TR5. I removed it and came to the realization that someone had either replaced it in the past or had messed with it in some manner. It was either installed incorrectly or the legs were shorted and touching the heatsink. This explains drwicket's somewhat strange measurements he got when testing the 2N6057. Earlier I noticed that a mounting bolt and nut for the heatsink was missing, this should have been a clue something else was wrong. I installed the 2N6057 correctly and everything works, and the test measurements came up the same as others that I have on hand.. All voltages check out fine, +5v is right at 5.0v, and my Star Wars plays fine with it installed.

I also replaced the 9 pin header at CN8 since the solder joints were looking ragged and it was cracked at a couple pins. I also repinned connector CN9 as it had obviously been hot in the past.

It will be on the way back to drwicket soon!