Any Help ???any Hope???

[kathodyne]

about input caps:

For the 5ar4:
maximum input capacitor (the one directly after the rectifier) max 60uf

for the 5u4:
DOesn't state maximum, the note says:
if a condenser bigger than 40uf is used, it may be necessary to apply more plate impedance

taken from the datasheets at franks electron tube page....

 

[mwcontract]

OK guys I found a nos mallory 40-40-20-20 450 volt,should i buy it??Mark

 

[Kegger]

My question for you "mwcontract" is the "60 40 20 20" you mention earlier on replacing
was this the original specs on the can in the unit?

If it was then I would definatly not go lower! My assumption would be then if the 5u4
could only handle 40uf to start with then the 60 must not be wired to the rectifier.
"makes sense to me the manufacturer is not going to overdrive the rectifier"

So I would get the new unit from tubesandmore I mentioned and I would replace the
5u4 with the 5ar4, do whatever work had to be done and fire the unit up.
That Is what I would do! From the experience with that rectifier tube in my St70 with
the (80/40/30/20 µF @ 525 VDC) can cap my unit works fantastic, so either my ST70
does not use the 80 on the rectifier, "possably like yours" or it can handle that capacitance!

All I can tell you is that I'm using that cap with that rectifier and it works great.

That's all the info I can give you is what I've done and speculate about your amp.
If It was mine I would use the (80/40/30/20 µF @ 525 VDC). But It's not mine and
I'm not working on it so, that's about all I got.