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Hi,
I'm adjusting my HDBP V2 but the voltage is not adjustable on one side.
It keeps at 19,95 V.
I am able to adjust the current and to get the voltage down with lowering the current.
What can possibly be wrong here?
Thx,
Jordo
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Oeps for everything there must be a first time. I inverted C3a somehow.... + and - were swapped... Edited by user Thursday, December 25, 2014 7:37:52 AM(UTC)
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Hm, now the voltage is increased to a steady 21v. Also the shunt is not adjustable and stays at a 60mV. I cannot mixed up voltage regulators since the RH side works as advertised. The pot meters adjust fine in resistance by the way. Edited by user Thursday, December 25, 2014 7:51:45 AM(UTC)
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I assume that it's the Placid 2.1.
Pls measure between TP_VREF and GND.
Can you post a picture?
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Hi Avr300, Thanks for your reply on this Christmas day! Yes it's the regular V2.1, not the Beta version. I will post pictures when I'm home this afternoon. (some people do work today  ) I've inspected the Print myself yesterday briefly. All solder connections seems fine and I only found one Capacitor (C3a) installed wrong (never happened to me). I hope this can do no harm? I will inspect the Voltage Regulators later for as far as possible. What do I measure between TP_VREF and GND? Voltage or Resistance? What Value should I expect? Many thanks in advance! Jordo
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Merry Christmas to you.
Measure voltage.
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Here some Pics in advance. Jordo attached the following image(s):  foto 2.JPG (104kb) downloaded 15 time(s). foto 4.JPG (87kb) downloaded 10 time(s). foto 5.JPG (105kb) downloaded 14 time(s).You cannot view/download attachments. Try to login or register.
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At first glance it looks ok to me
Lets see the voltage between TP_VREF and GND
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Ok, thx for the assurance.
I think I will make measurements tomorrow. I have to build the other unit out and it will take some time before I have the V2.1 connected properly. It's a little crowded in my case (chassis) :)
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ok.
Make sure that you haven't mixed up the QP/QN and the REFx's.
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Yes indeed. I was very aware of that. The only ones I havn't been able to check are QP3 and QP5. They are too close together to read their numbers. But they have to be okay since the RH side of the board works fine and QP4 has the correct p/n even as REF1A and 2A... We'll see. Thanx for so far! And, I populated the board in a way that avoid these errors. But you never know... Edited by user Thursday, December 25, 2014 1:22:09 PM(UTC)
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Well they are identical. So if all other transistors are in correct position and Brian has supplied the correct numbers (I'll bet he has) QP3 and QP5 are fine.
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I took the measurements:
TP_VREF + = 2.49 V
TP_VREF - = 2.49 V too....
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Now let try to have some more numbers. @attachment. The green spots you already have measured, ~2.5v. Good. Lets see the result of measurements in the other yellow spots. avr300 attached the following image(s): cut.JPG (47kb) downloaded 23 time(s).You cannot view/download attachments. Try to login or register.
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Hi AVR, I took the measurements first thing this morning. Yesterday I was still celebrating Christmas (we have two day's in Holland) IC 1- 3 = 3.34V IC 2- 3 = 2.50V VR2A = 3.97V VR2B = 2.49V R8A = 21.1V R8B = 14.3V As you can see all the values differ between the left and the right side. I did not equalled the Potmeter values before I took the readings. I also added the values in the picture attached. I would say that R13A must have a lower resistance than R13B but the markings have the same colours and they measure both 470R. I'm curious about your judgement... Thx! Jordo Edited by user Saturday, December 27, 2014 11:19:20 AM(UTC)
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Something around the 3.34v positive input is wrong. Can you please check the value of the resistors, that will be R6 and R13. Also double check the Vref+ voltage (green spot). Then check voltage in all 3 red spots. avr300 attached the following image(s): cut.JPG (47kb) downloaded 8 time(s).You cannot view/download attachments. Try to login or register.
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Both Vref's are still 2.49V R 13 A and B measure both 470R R6A measures 1988 R (2K) R6B 1158 R They have the same colour code... R6A voltage = 2.49V on the inside of the board R6A voltage = 20.6V on the outside of the board towards the current pot. Ref 2A-2 = 0.6V R13A Voltage 2,49 on the inside of the board and 3.32V towards C8A Edited by user Saturday, December 27, 2014 11:39:16 AM(UTC)
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ok.
Check for tiny (tiny) solder bridges around the OPAMP (IC1).
Reflow all solder joints.
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Ok I will this afternoon.
I have to go for now.
But don't you think the difference in resistance around the R6A/B isn't remarkable?
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