65 Fender DRRI

Fender Amp Discussion

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Rockwell666
Posts: 136
Joined: Mon Nov 21, 2016 4:56 pm

65 Fender DRRI

Post by Rockwell666 »

Hey guys, My bandmates 65' Deluxe reissue stopped working on the vibrato channel. Tested the tubes and all test good. measuring the volume pot resistance I am getting less then 1K ohms across the volume pot... so naturally I scoped the signal. it seems ok going into the volume pot, it doesn't come out the wiper, regardless of position.... measuring resistance from ground to pin 7 on V4B I get around 800ohms regardless of the pot position. so I removed the pot and it seems to functioning properly out of the circuit.. I removed the 47pf bright cap. same issue. I will try swapping in another pot but I cant help but feel its not related to the pot. any other ideas to try?
Rockwell666
Posts: 136
Joined: Mon Nov 21, 2016 4:56 pm

Re: 65 Fender DRRI

Post by Rockwell666 »

its the pot :-)
tubeswell
Posts: 2337
Joined: Thu Mar 27, 2008 6:42 am
Location: Wellington. NZ

Re: 65 Fender DRRI

Post by tubeswell »

I had one in for repair a couple of months back. The traces on those PCBs are prone to cracking and becoming open.

So before you go to the time and expense of replacing the pot, you should measure for DC continuity between each of the pot lugs and the other parts of the circuit they are supposed to connect with (using your R-meter). You will either get a low or high resistance reading if there is some sort of connection. But if you don't get any reading, then you may have to resort to jumpering between components.
He who dies with the most tubes... wins
Stevem
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Re: 65 Fender DRRI

Post by Stevem »

Do your buddy a favor and scrape off the circuit board masking a jumper out the volumes on both channels if he uses them, and then tell him to be more carfull with his amp and not bang the front of them into things, lol!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!😊

Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Rockwell666
Posts: 136
Joined: Mon Nov 21, 2016 4:56 pm

Re: 65 Fender DRRI

Post by Rockwell666 »

pot is shorted internally. wiper to body is under 1k ohms. The traces are weak on this thing.
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