PS voltage changes after capacitor replacement

[ronenash]

Hi all,

I need some help with a problem I am having. I have an old Beard P100 KT88 based power amlifier. The power suply of the beard is regulated to 580v. I replaced the power suply electrolitic capacitors and notied that after the change the power suply now provides 620v. Originally the power suplly used a two dual section 400uf+400uf 350v capacitors in series which I replaced with two JJ 800uf 385v connected in series. See the attached schematic.[IMG]C:\Users\ronena\Desktop\capture.jpg[/IMG]

Do I need to replace the capacitor load resistor as well? Any idea what's going on?

Thanks
Ronenash

[ronenash]

Now with the schematic attached.

The dual section 2*400uf 350v capacitors were replaced with JJ 800uf 385v

Thanks
ronenash

[kruesi]

It's possible (likely?) that the old capacitors had so much leakage they were dragging down the B+ -i.e. their internal resistance was low enough to reduce the B+ voltage.

They may read OK at a lower voltage- but may break down near their operating voltage.

Just a guess.

If the resistors read OK, look OK, and smell OK, there's likely no need to replace them.

[leadbelly]

First of all, your supply is not regulated according to that schematic.

Second, did you actually measure 580VDC, or are you just quoting the schematic?

Third, how did you measure 620VDC? Was the PS installed in the amp, and the amp was working and under load?

If all you did was measure 620VDC with your amps tubes pulled and the only reason you believe it was 580VDC with the old caps is that was written on the schematic then there is no problem.