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Problems vid Placid BP - Unable to adjust voltage on negative side
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Crumboo  
#1 Posted : Tuesday, March 25, 2014 5:47:45 PM(UTC)
Crumboo

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Hi,

I recently put together my Placid BP for powering 4xIVY (well, the same schematics and parts but home made pcb:s).

I successfully adjusted the voltage (+15V) and shunt current (50 mA) on the positive side. But on the negative side I can't get the right values. I cannot get more (or less as it's negative) than -10V.

Also, I noted that while both heat-sinks get slightly warm on the positive side, only one of them gets warm on the negative side (the other one stays cold).

What more can I check in order to identify the problem? All LED's lights up. The AC input is at 16V on both rails.

Best regards,

Mattias
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Brian Donegan  
#2 Posted : Tuesday, March 25, 2014 6:20:56 PM(UTC)
Brian Donegan

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Most common issues:

  • Cold/bad solderjoint(s)
    Transposed small signal transistors
    Reversed diode (D1A/B)


Give those a look and report back. Photos often are very helpful.

Also, do you have the supply connected to a load? Have you tried with no load?
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WWW
Crumboo  
#3 Posted : Wednesday, March 26, 2014 8:10:38 PM(UTC)
Crumboo

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Thanks Brian - it was probably some solder joint. I reworked them and now the unit work as it should!:)
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dsolodov  
#4 Posted : Saturday, March 29, 2014 2:00:34 AM(UTC)
dsolodov

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I have a question on temperature of QN1 and QN2 on Placid HD v.1.0. I built a couple of them, and tried to run both open sitting on a table. On both PSUs the temperature of QN1 (~51C-> 123F) is about 20C (36F) higher than the T (31C -> 87F) on QN2. I used Fluke 62 Mini IR thermometer after about 1/2 hour of operation. Is such temperature differential to be expected?

[TP_VIN+, TP_CCS+] => ~500mVDC
[TP_OUT+, TP_SHUNT+] => ~45mVDC
Vout => ~5.25VDC
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avr300  
#5 Posted : Saturday, March 29, 2014 8:06:01 AM(UTC)
avr300

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It normail
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thanks 1 user thanked avr300 for this useful post.
dsolodov on 3/30/2014(UTC)
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