Troubleshooting 5f6a build

[sluckey]

It’s kinda hard to tell from your photo, but it looks to me like you have the orange 600 volt ground / death cap connected to your standby switch and not the AC power switch.

Thanks, the orange death cap is wired from the ground lug to the upper left lug of the standby switch like this (from Mojotone schematic)

That's not the death cap. The death cap would have been connected to the GROUND switch but Mojo decided not to show it on the layout drawing. However, you can see the death cap on Mojo's schematic.

That orange cap is wired correctly. You can also see that cap on the original Fender schematic/layout. That cap is also on most of the Fender tweed amps that have a STBY switch. It is supposed to decrease arcing and pops on the STBY switch, providing a bit of protection for the rectifier tube. Later on when the brownface amps came out, Fender put a filter cap between the rectifier and the STBY switch and the .05µF cap was no longer needed.

[ragamuffin]

I took a look under the doghouse and found what looks like a blown/leaking filter capacitor. I assume it needs to be replaced, but what about the other three? (which look alright). Could this be the cause of my problems? Or just a symptom?

[Lynxtrap]

Are you sure the solid state diodes are soldered to the right lugs on the rectifier socket? It's hard to tell from the pics, but it looks to me like one of them is going to pin 7 instead of pin 6.

[ragamuffin]

Are you sure the solid state diodes are soldered to the right lugs on the rectifier socket? It's hard to tell from the pics, but it looks to me like one of them is going to pin 7 instead of pin 6.

Thanks, there on 3 to 4 and 5 to 6 with the silver markings facing 4 and 6

[martin manning]

...3 to 4 and 5 to 6 with the silver markings facing 4 and 6

That sounds ok. Measure resistance to ground at the power supply nodes (filter positive leads) to look for a short.

[ragamuffin]

Thanks guys, I finally found my issue: I had switched two of the wires that go to the filter caps. After replacing the filter caps and wiring correctly the amp is now working great!

The Mojotone layout that I was following showed one red wire and three yellow wires going to the filter caps board but did not specify which yellow wire was coming from where, so in my ignorance I assumed that I didn't matter which yellow wire went to where.

[martin manning]

One of the yellow wires is a ground... that's the only one that maters.