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kesgreen  
#1 Posted : Thursday, June 18, 2020 6:51:04 PM(UTC)
kesgreen

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Hi, I have a Placid BP (v2.1.2).

I can't get the negative rail below 22V. I can adjust VR1 and VR2 to get 15Ω, and VR3 and VR4 to 2KΩ and I can adjust the positive rail to 15V and R2 to 0.25V, but VR3 has litttle effect on voltage and I can't adjust VR1 to get 0.25V across R1.

I can get the trimpots online, but I guess I need to replace the FJPF1943RTU PNP Bipolar Power Transistor? I see that they're obsolete and that there are some in the parts bin, but the postage costs are five times the cost of the item. Is there anywhere in the UK/Europe I might be able to find them or somewhere with cheaper postage costs?

Failing that, perhaps there's a suitable replacement part?

Edited by user Friday, June 19, 2020 5:09:19 PM(UTC)  | Reason: Not specified

kesgreen  
#2 Posted : Friday, June 19, 2020 6:32:41 PM(UTC)
kesgreen

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I couldn't wait any longer, so I ordered them from you!
kesgreen  
#3 Posted : Tuesday, July 7, 2020 1:29:55 PM(UTC)
kesgreen

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Negative rail transistors received (thenk you!) and installed. I adjusted VR1 to 15 ohms, but when power is supplied the LEDs on that side don't light. If I turn it slightly, D6 lights but D3 and D4 do not. the output voltage jumps from ~13V to ~21V when turned very slightly. I cannot get it to output 15V. Maybe VR1 is faulty?
Brian Donegan  
#4 Posted : Sunday, July 12, 2020 8:06:08 PM(UTC)
Brian Donegan

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Very possible. Could also be a cold solder joint.
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