Rank: Member
Groups: Member
Joined: 9/7/2011(UTC)
Posts: 3
Location: Greece
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Ok I have completed assembling my Placid HD power supply intended for supplying the Buffalo III DAC board. I connected my 9V 50VA transformer and set VR1 to 450R and VR2 to 1K. The leds light up, no smoke :-) and the vout is 5.4V. Now when I try to adjust voltage through VR2 nothing changes... Up to a point where voltage jumps to 9.5V and stays there. Checked the VR1 and VR2 to ensure they operate properly and they do consistently throughout their ranges. Doublechecked the solder joints. Also some extra measurements TP_GND1 - TP_VIN+ = 10.9V TP_GND1 - TP_CSS+ = 10.55V TP_VIN+ - TP_CSS+ = 0.15V TP_GND2 - VREF+ = 3.85V TP_GND2 - TP_OUT+ = 5.48V TP_GND2 - TP_SHUNT+ = 5.25V TP_OUT+ - TP_SHUNT+ = 0.15V And some photos     Any ideas?
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Rank: Member
Groups: Member
Joined: 9/7/2011(UTC)
Posts: 3
Location: Greece
|
After spending many hours resoldering, and replacing all the bc transistors to no result I noticed that the QN1, QN2 were instead the QP1, QP2 for the other part of the Placid Bipolar kit....  Replaced those two with the correct transistors and everything worked as it should. I learned my lesson the hard way. Always check the components before soldering them. Even if they come in neatly packed kits such as the TP ones.
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