2009 Fender Blues Deluxe Reverb Hum and... A poor past repair??

[Steelwitch]

The Illinois electrolytic caps in those are notorious for being bad. Take a known good cap of similar value properly voltage rated and clip it across each cap in the amp, one at a time, to see if the hum goes away.

Also, will the amp bias properly?

Thanks for your suggestion. It looks like the 47uf 500v filter cap is the source of all of this. Unfortunately I don’t have one in stock (which sucks I thought I did!) but when I clipped 2 22uf caps across in parallel, the issue was gone. Still kind of noisey, but completely in the right direction.

[Steelwitch]

The Takeaway: Illinois Crapacitors gotta go! It completely sucks that an amp made in 2009 has a bad cap in it...

[g1]

Did you check whether R52 is stuffed with a resistor on the circuit board? If it is not, and you remove the 'mod' version, the circuit will have issues.

[Steelwitch]

Yup, R52 is unpopulated

[Steelwitch]

I’m tempted to do this out of convenience... but I do have 2 22uf 500v caps. Would it be feasible to use them in parallel as a permanent replacement? It’s a time sensitive repair unfortunately, but I figured the value is similar enough to be totally fine. Has anyone done this?

[g1]

Yes. If you can mount them so nothing is hanging loose or flopping around, I don't see any problem using 2 caps paralleled like that.
I hope you are going to restore the factory mod?

[Steelwitch]

Already done! dang trying to get this out of here TODAY