Hum in MV Twin Reverb

[Chuck H]

Sorry for the second post. The forum isn't allowing editing at this time. So, to add...

How do you know if touching up the solder under the doghouse actually did anything? If you replaced the PI tube at the same time as the solder work, you can't know. You can only believe it did. This sort of prolonged failure to diagnose can lead to a lot of frustration and re shelving projects. Don't fall into that.

[earache]

Hi -

I had already been thru all of the tube sockets, sprayed them with DeOxit, touched up the solder joints on the sockets and retensioned them.

The reason things happened how they did is this: I have recently acquired an old capacitor analyzer that my work was throwing away, a Sencore LC103. I unsoldered one leg of all the new capacitors and had begun testing them with the analyzer when it became apparent that the device needs to be recalibrated, because it was giving results that weren't consistent. That's how I came to retouch the solder joints.

I swapped in the different Phase Inverter because it was on the list of things that I thought I should try as I retraced my steps from earlier troubleshooting. I realize I should have tried out the amp between steps but I didn't because I didn't want to bleed the caps off again in between different tests. I know it doesn't make for a very good cause-and-effect trail. I will pay better attention to that from now on.