ampage Tube Amps / Music Electronics	For current discussions, please visit Music Electronics Forum.

ampage archive

Vintage threads from the first ten years

Pro Reverb Hum Problem

9/12/2000 2:03 PM
JCS	Pro Reverb Hum Problem Hi All, I have a freinds BFPR in for a tune up. I replaced all bypass caps, bias cap, plate load res and a couple misc res along the way.Tubes all test OK and where swaped around to check for problems. The filter caps where replaced before he got this (about 5 years ago) with Illinos. He is on a tight budget, so I left them in there.There is a hum at all times with this amp. On the bench with no reverb tank, it gets louder as I turn up the reverb pot, and there is still a noticable hum when every knob is on zero and no input signal applied. When the amp is hooked up to the tank and speaker cab everything works. You can hear some reverb coming through with the pot on zero. The hum goes away when I remove the reverb recovery tube or the P.I. tube. Also the volume pot on the reverb channel has a funky hum range when the knob is turned,the hum comes and goes depening on the setting. The pre amp plate volts on pin 6 of the reverb recovery and 1st gain stage are a little high. About 310v, the sch calls for 260v- 280v. Any input on this would be much appreciated. Thanks JCS

9/12/2000 2:03 PM

JCS

Pro Reverb Hum Problem

Hi All, I have a freinds BFPR in for a tune up. I replaced all bypass caps, bias cap, plate load res and a couple misc res along the way.Tubes all test OK and where swaped around to check for problems. The filter caps where replaced before he got this (about 5 years ago) with Illinos. He is on a tight budget, so I left them in there.There is a hum at all times with this amp. On the bench with no reverb tank, it gets louder as I turn up the reverb pot, and there is still a noticable hum when every knob is on zero and no input signal applied. When the amp is hooked up to the tank and speaker cab everything works. You can hear some reverb coming through with the pot on zero. The hum goes away when I remove the reverb recovery tube or the P.I. tube. Also the volume pot on the reverb channel has a funky hum range when the knob is turned,the hum comes and goes depening on the setting. The pre amp plate volts on pin 6 of the reverb recovery and 1st gain stage are a little high. About 310v, the sch calls for 260v- 280v. Any input on this would be much appreciated. Thanks JCS

Replies:

Richie{~}==::: Does this amp have the 100 ohm resi... -- 9/12/2000 11:18 PM
Richie{~}==::: And check the jacks..make sure they... -- 9/12/2000 11:20 PM