Let me start with stating, I’m below the novice level. With that being said, I did build two M125s without any problems. They fired up day one and have been in service for over a year. This speaks to Bob’s amps not my abilities.
Amps had been on for a few hours. When I was changing albums (no music playing) heard a pop, and one of the amps blew the fuse.
With power tubes and rectifier (WZ68) out, the unit powers up without blowing the fuse, with WZ68 in fuse blows. I put in the WZ68 from the other M125, and power tubes, it did not blow the fuse. So I concluded, WZ68 was bad, and ordered two new ones.
My concern is what may have caused the rectifier to die in the first place. I installed the good WZ68 from the second amp and started to adjust the bias setting. I noticed anytime my hand was close to the tubes in the driver board there was an increase in voltage on one channel and a decrease on the other. This would happen without touching anything, just getting close. A visual inside and out didn’t reveal anything suspicious. What can cause this?
I don’t want to install the new WZ68 only to mess something else up.
Any help on what to check would be greatly appreciated.
Thanks
Amps had been on for a few hours. When I was changing albums (no music playing) heard a pop, and one of the amps blew the fuse.
With power tubes and rectifier (WZ68) out, the unit powers up without blowing the fuse, with WZ68 in fuse blows. I put in the WZ68 from the other M125, and power tubes, it did not blow the fuse. So I concluded, WZ68 was bad, and ordered two new ones.
My concern is what may have caused the rectifier to die in the first place. I installed the good WZ68 from the second amp and started to adjust the bias setting. I noticed anytime my hand was close to the tubes in the driver board there was an increase in voltage on one channel and a decrease on the other. This would happen without touching anything, just getting close. A visual inside and out didn’t reveal anything suspicious. What can cause this?
I don’t want to install the new WZ68 only to mess something else up.
Any help on what to check would be greatly appreciated.
Thanks
Last edited by mikew on Mon Sep 09, 2013 7:15 pm; edited 1 time in total (Reason for editing : wrong name)