Marshal JMPl cathode cap question

[Helmholtz]

I think the less professional cap checkers (like found on DMM) will show leakage as increased capacitance. So it is actually a measurement error. The principle is the same as Enzo outlined in post #5, just no resistor but cap leakage instead.
So, a good reason to be suspicious of caps that measure high when using a DMM cap function.

Sure, no doubt. BTW, analog C-meters often just measured impedance.

Nevertheless I thought it might be good to know that the capacitance of ecaps doesn't increase with operating hours.
So if a meter shows strongly increased capacitance, it indicates both: high leakage and an unreliable C-meter.

[Chuck H]

FWIW when I owned that Marshall is when I started bending my soldering iron tips. I put an arced bend in my tips and have learned to use them that way. I don't even think I could use a straight tip anymore. You can undo the standoffs and lift the board a couple of inches without unsoldering all the leads. Then, with an arced tip you can reach a remarkable amount of the circuit.

Submitted for your consideration.

[drewl]

"I'd lift one end, if it measures 300-360uf, leave it be. "

Well, of course so would I if I had reasonable access to it. Not wanting to disconnect umpteen connections to measure a cap, but if the board is coming up anyway, it's getting replaced.

If you have a curved soldering iron tip, you could heat one end underneath the board.

I wouldn't bother if the voltage is okay, there's only like 1.5 volts on there, and they don't go bad very often.

[Helmholtz]

A leaky cathode cap would cause the plate voltage to be low.

Even if capacitance would be higher than specified, I don't expect an audible difference.