Oh great TAG gurus, please help!
A 65 TRRI came in for repair and the guy said that it was distorting too early. I did the standard of checking all caps and resistors, and lifting ends of ones that were reading bad in situ and everything checked out just fine. While scoping the signal and referencing the repair manual, I injected a 47mv 1k sine into input 1 of the reverb channel with all controls maxed. On pin 6 of V2 I should be reading about 3.1 vac when in reality I'm reading closer to 25vac!
At first I thought it might be a bad coupling cap in the tone stack so I replaced all of those and the problem is still there. Once you go above 4 on the volume with all controls set at 5 it distorts quite a bit. In addition, the tube itself seems to be making an audible reproduction of the test signal, which was confirmed when I went from 1k to 2k and so on upwards. While back inside the amp trying to recheck my vac voltages off the test tone I found that pushing pin 6 a certain way dropped the voltage to the right amount and the sound disappeared. I concluded that the problem was in the tube socket but when I replaced it the sound is back and now no amount of prodding the damn thing with a chopstick will make it go away. Has anyone every had this problem? I've gone through everything on the circuit board and it all appeared to check out ok and now I'm starting to pull my hair out. This amp has been to multiple techs and the guy says its never come back fixed so I wanted to give it a shot. Any help would be much appreciated!
Fender TRRI 65' V2 Trouble
Moderators: pompeiisneaks, Colossal
Re: Fender TRRI 65' V2 Trouble
Hey, I'm pretty new to this forum and certainly no guru, but since you haven't gotten any replies yet maybe I'll take a shot.
Have you checked TP4 and TP5 on the schematic and gotten the numbers you're supposed to? Also, the schematic I have specifies a 37mV input signal with all normal channel controls off and all vibrato channels at 50%. Not sure if that would explain the difference or not.
Have you checked TP4 and TP5 on the schematic and gotten the numbers you're supposed to? Also, the schematic I have specifies a 37mV input signal with all normal channel controls off and all vibrato channels at 50%. Not sure if that would explain the difference or not.
Re: Fender TRRI 65' V2 Trouble
Look at the pot that is driving the grid of that triode.