Bassman Bias Circuit Questions

[tbbeck]

In a recent 5f6a build Ive ran into a problem with my bias circuit. A 50v tap from the power transformer runs to the cathode end of a 1n4007 diode and then to a 10uf 100v cap, followed by a 15k resistor, another 22uf 50v cap, and finally a 50k bias pot. Unfortunately when I power it up the first 10uf cap keeps blowing. I've double checked my wiring and I can't seem to figure it out. Any ideas as to what might be happening? Attached is a schematic of the problem area.

[statorvane]

Can you post a photo of your amplifier's bias circuit wiring?

[ToneMerc]

Sounds like that first cap is not orientated correctly, is the positive end grounded?

TM

[CHIP]

Sounds like that first cap is not orientated correctly, is the positive end grounded?

TM

That's what it sounds like to me. I did it once, the e-cap went off like one of those black cat firecrackers that we used to play with as teenagers.

[Stevem]

Blown off firecrackers smell way better than popped elec caps! LOL.

[billyz]

Your schematic is wrong. Positive to ground not cathode. Your making negative voltage not positive. Reverse both caps!

[martin manning]

Looks OK to me- although it isn't marked, the straight plate in the symbol is the positive end.

[billyz]

Ok, my bad . Alzheimer's . Looking at the cap thinking diode.

[vibratoking]

The cap orientation in the schematic looks correct. Did you wire it according to the schematic? The schematic shows the postive end of the cap to ground. The fact that it is blowing up indicates that you are putting it in backwards.

[roberto]

I bet on reverse polarity.

[printer2]

Popped the first cap myself on my current build. So used to seeing the negative grounded I automatically hooked it up that way. Won't be doing that mistake again.

[Teleguy61]

2 for reverse.