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Post subject: '65 Twin reissue volume pot question
Posted: Mon Feb 27, 2017 1:46 pm
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Hello all. I've spent several hours going over older entries, and haven't found an answer, so looking for some info on this.

I received a Twin Reissue that has been played all of 4 times, and recently came by way of a road trip, so plenty of jiggles and bumps. The amp was bought new as a Christmas present in 2013 by the original owner. They left it to me, passing on to bigger/better things. Anyway, I went to try it out, and it sounds pretty good, except the reverb was not working much (had a sort of constant ghost sound), and that was resolved by reseating the tubes (all look stock, except for the PI being an older JAN Philips 12AT7).

The real head-scratcher for me is that the normal channel volume works normally. No volume output when all the way down. The vibrato channel does not do this. I get a little bit of ouput (a bit thin, but mostly full spectrum) conversation level in volume, with a hint of distortion. Looking at the schematic for the amp, this shouldn't really happen. Bright switch was not engaged, and seems to work properly.

So, I'm wondering if the volume pot on the vibrato channel is somehow bad, a board/trace/solder/tube issue, or is this really just normal operation for that channel (doesn't look like it should be)? It happens regardless of reverb/trem being on or off.

I don't recall if the amp did this previously, as the volume was up for the other times it was used. Any suggestions?

Thanks!


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Post subject: Re: '65 Twin reissue volume pot question
Posted: Tue Feb 28, 2017 4:38 pm
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One side of the volume must go to ground. If not or bad solder, pot can't silent the volume.
Or a dirty pot ?


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Post subject: Re: '65 Twin reissue volume pot question
Posted: Tue Feb 28, 2017 4:46 pm
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stratele52 wrote:
One side of the volume must go to ground. If not or bad solder, pot can't silent the volume.
Or a dirty pot ?


Correct.

Try some Caig De-Oxit contact cleaner on the pot's shaft (best to temporarily remove the knob). Spray liberally then briskly spin the shaft from stop to stop several times. Repeat as necessary. If the symptom remains I'd guess that the pot is shot.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: '65 Twin reissue volume pot question
Posted: Tue Feb 28, 2017 11:10 pm
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No static at all in the pot, so I'm doubting it's dirty, though I'll take a look at the solder joints when I have some time. As I've been reading more on these amps, it seems they can be temperamental. Thanks for the input!


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Post subject: Re: '65 Twin reissue volume pot question
Posted: Wed Mar 01, 2017 2:59 am
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Thundersmuckers wrote:
As I've been reading more on these amps, it seems they can be temperamental. Thanks for the input!


I don't know who's writing that tripe but I'm the second owner of a 1999 TRRI purchased in 2001 and it's never been "temperamental". I also own a 1978 Twin Reverb that I bought new in March of that year and it's never been "temperamental". Prior to those, I've owned perhaps three or four more Twin Reverbs (both blackface and silverface) and they were never "temperamental". All were rock-solid dependable and required very little maintenance or repair. Fix your volume-control issue and you'll have a friend for life.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: '65 Twin reissue volume pot question
Posted: Wed Mar 01, 2017 4:22 am
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Retroverbial wrote:
Thundersmuckers wrote:
As I've been reading more on these amps, it seems they can be temperamental. Thanks for the input!


I don't know who's writing that tripe but I'm the second owner of a 1999 TRRI purchased in 2001 and it's never been "temperamental". I also own a 1978 Twin Reverb that I bought new in March of that year and it's never been "temperamental". Prior to those, I've owned perhaps three or four more Twin Reverbs (both blackface and silverface) and they were never "temperamental". All were rock-solid dependable and required very little maintenance or repair. Fix your volume-control issue and you'll have a friend for life.

Arjay


+1

I often read wrong information on the web.

Thundersmuckers, try what we write; clean pot and check solder


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Post subject: Re: '65 Twin reissue volume pot question
Posted: Wed Mar 01, 2017 7:54 am
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Some of it came from the Fender forum, as I spent several hours reading posts, and anecdotal stories about solder joint issues in the reissues (Deluxe and Twin respectively). I've run across several other forums with similar stories, though I've not found one regarding a volume pot not cutting all output, though I have seen plenty of "weak, low output,' threads.

As for older years, I used to practice/gig a '68 Bassman 50W head that needed nothing, though I didn't push it beyond 6 in volume. I still have it in storage to this day, with its old Baldwin tubes. With that said, this thread is not about the old amps. This is about an amp that was played, for the 4th time since purchase, below volume 3, and had an anomaly (possibly from the start, but I never checked for zero volume).

I'll look at cleaning the pot, although there really is zero static when moving it, and the amp is pristine, since it's been covered when not played. One never knows until they try, though my initial though was bad pot or solder joint.


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Post subject: Re: '65 Twin reissue volume pot question
Posted: Wed Mar 01, 2017 10:42 am
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Solder-joint issues *are* a legitimate concern with the re-issues, especially if the amp was built in 2006 or later (when Fender adopted RoHS-compliant solder). And they can be very frustrating to isolate and identify.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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