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  1. Enginuitor

    Help with power supply repair

  2. Enginuitor

    Help with power supply repair

    Uh oh... Just got a quote from MicroSemi, the only known maker of the PIC647: o__0 Methinks it may be time to research an acceptable alternative to this IC! Here is the manufacturer's datasheet: http://www.microsemi.com/datasheets/WT7-12.PDF Below is a schematic of the PIC647. It is...
  3. Enginuitor

    Help with power supply repair

    Q1 base is about 12.6 volts. Q1 emitter is about 12.2 volts. Q9 base is about 3 volts with C5 disconnected from input side, and does the ramping thing (0 to 45 volts) when C5 is fully connected. Q9 emitter is of course the final voltage output, and also does "the ramping thing". Very curious. I...
  4. Enginuitor

    Help with power supply repair

    Took some more measurements on U9. Its output with the cap disconnected reads on the meter at about 19VDC with voltage knobs turned all the way down, and 23VDC when turned all the way up. In addition, when switching the meter to AC, it reads from about 1.1 volt to 0.8 volts respectively, at...
  5. Enginuitor

    Help with power supply repair

    Interesting. The U9 input is at about 65 volts (it's connected directly to the input) while the U9 output behaves exactly as the final voltage output; it ramps slowly up to about 45 volts before the OVP kicks in. Next, I will disconnect C5 on the input side so I can see exactly what's coming out...
  6. Enginuitor

    Parts from stuff

    Desoldering is putting a soldering iron against the solder to re-melt it, then either using something to wick/suck it away, or just pulling the component out while it's still hot.
  7. Enginuitor

    Parts from stuff

    Why not just desolder them??
  8. Enginuitor

    Help with power supply repair

    Thanks again Ante! After I get all my real-life duties taken care of today, I'll hunker down and start taking measurements. Updates to come...
  9. Enginuitor

    Help with power supply repair

  10. Enginuitor

    Help with power supply repair

  11. Enginuitor

    PSU repair, found strange cap, need guidance

    Thanks for all your help. Since we're past the capacitor issue, let's move this discussion into my other thread (Electronics Chit-Chat -> "Help with power supply repair") so we don't have to jump back and forth.
  12. Enginuitor

    PSU repair, found strange cap, need guidance

    Here is the schematic for those who don't want to deal with the PDF: Click here to enlarge
  13. Enginuitor

    Help with power supply repair

    I was halfway through the calibration steps when a wispy trail of magic smoke lead me to R43 (see schematic). Perhaps something has gone wrong with U2 (MC1723CG) or the surrounding circuitry. I would appreciate anyone's input. I have posted the full schematic so people no longer have to...
  14. Enginuitor

    PSU repair, found strange cap, need guidance

    Long story short, I set up the back terminal strip according to the strapping diagram for local sensing and control. It miraculously worked!... For a short period of time. Everything was working fine, so to test the current output I put a small wire across the output. I started easing the...
  15. Enginuitor

    Help with power supply repair

    It miraculously worked!... For a short period of time. Everything was working fine, so to test the current output I put a small wire across the output. I started easing the current up, and it did fine up to about 3 amps, then suddenly the needles dropped to zero. I think I may have heard a...
  16. Enginuitor

    Help with power supply repair

    Found an operation & maintenance manual! Luck just doesn't get any better than this... http://www.elgar.com/pdfs/manuals/PowerTen/3101A%20Series%20Models%204006%20and%204010%20Operation%20and%20Maintenance%20Manual.pdf Remember that strange screw-terminal header I mentioned? As I gathered...
  17. Enginuitor

    PSU repair, found strange cap, need guidance

    Guess what Iiiii fooouund... http://www.elgar.com/pdfs/manuals/PowerTen/3101A%20Series%20Models%204006%20and%204010%20Operation%20and%20Maintenance%20Manual.pdf ;D
  18. Enginuitor

    Whoops!

    Just a reminder to everyone to use sufficient work lighting when sticking probes into live high-power circuits... I couldn't really see what I was doing, and managed to convert the last several millimeters of my nice needle probe into plasma by inadvertent contact with two adjacent power traces...
  19. Enginuitor

    PSU repair, found strange cap, need guidance

    I traced the VIN lead and it brought me straight back to the zener/reisitor circuit I mentioned earlier. As it turns out, this is actually a crude voltage regulator. The resistor is connected between the positive supply voltage and the cathode of the diode. The anode is grounded. This is a 12V...
  20. Enginuitor

    Help with power supply repair

    An update on the overheating components. It appears it is due to a poor design rather than some kind of failure. The resisitor and zener diode are essentially being used as a crude voltage regulator. The diode drops 12 volts in reverse, so by running power across it (I.O.W. putting it straight...
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