Quote:
Originally Posted by jr_tech
1. Does the hum actually get louder as you turn the volume control down?
2. Can you measure the voltage of the hum at the speaker?
Sometimes increasing the capacitance value of of a filter cap too much can cause 60hz current spikes that will propagate throughout the entire ground system of the set and cause hum problems. More is not necessarily better. 
jr |
The hum just appears when the volume is lowered to minimum, gradually you can here it the lower it goes, then it's just a nasty hum. Volume at minimum IIRC the voltage was nearly nothing but my Dvom has a hz setting and with the grid off I'm getting a full 60 hz from the speaker. These big caps I used IIRC I used then in one of my other vt71 sets and don't have any problems with hum.