Finally working to revive an old friend

sunvalleylaw

sunvalleylaw

Yep.
My 1961 Concert started acting up several months ago, and eventually came to the place that I did not feel I could play it a few months ago. It was starting to make a little noise now and then several months ago, then it started making a loud grunchy sound if I bumped it in any way, and/or sometimes if I was playing hard with some dirt pedal on. I wasn't playing that much and so just started using my C-30. But now I am playing again and motivated to revive her.

A friend suggested that I test the tubes by tapping with the eraser end of a pencil, and sure enough, a couple of the tubes in the middle of the line of 5 pre-amp tubes make sounds coming through the speaker. The power tubes seem very quiet. Also at the suggestion of my friend, I tried swapping those tubes back and forth, and though it got a bit quieter maybe, it was still there.

I found an amp tech that is supposed to be good and is Fender certified in Twin Falls, about and hour and a half or so south, or I could just buy a new set of tubes from eurotubes or somewhere and try that. What do you guys think? I guess it seems like I will need the new tubes anyway, so I could try that first. But the amp tech may have a different recommendation for the tubes. It is $40 deposit for diagnosis, then an estimate would be prepared.

Advice? I want to get this amp up and running again. She sounds so good when happy.
 
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How much maintenance has it had done over the years? Have all the electrolytic caps been replaced?

I would like the tech do a check-up, check the age of the filter, bias and cathode-bypass caps; check the plate and screen resistors (which bake over time); swap out and bias the tubes; etc.
 
My only recommendation would be that he do no work unless you sign off. You don’t want him to strip it of original components. Anything that gets changed out, you get the original parts back. Make minimal changes from the original parts.
 
If you replace the power tubes you'll need to have the amp biased, so (unless you know how to do that yourself) I think a trip to the amp tech is in order either way.

It's probably a good idea to give the amp a top-to-bottom checkup if you're planning on gigging it.
 
If you've never had a tech take a look at it, I think that would be a good idea. As others have mentioned, if the caps haven't been replaced, they will need to be. That may not be contributing to your issue, but for the sake of the amp, you'll want that done.
 
Also keep in mind that the preamp tubes in gain stages will make some noise as you tap them. Absolutely silence is probably not realistic.
I would think at he very least you’ll need a power tube replacement and bias (you MUST bias).
Preamp tubes are easy....all you do is plug them in...no biasing necessary. And if your amp hasn’t been looked at in a long time filter caps should probably be replaced too...altogether I’d think you are looking at about $200-ish.
 
smurfco said:
If you replace the power tubes you'll need to have the amp biased, so (unless you know how to do that yourself) I think a trip to the amp tech is in order either way.

It's probably a good idea to give the amp a top-to-bottom checkup if you're planning on gigging it.
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telecaster911 said:
My only recommendation would be that he do no work unless you sign off. You don’t want him to strip it of original components. Anything that gets changed out, you get the original parts back. Make minimal changes from the original parts.
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Bottom line, I think I am bringing it in for that checkup. I know too little about the amp to know when it was last serviced (before I got it in early 2010, that is for sure).

Howie and a couple others have talked about this amp with me before. I tried to sell it a year and a half back or so. It is not completely original, and was gone through prior to my owning it. I have not dropped the chassis out recently, but learned a little when I got it. It has a mercury magnetics bassman style output transformer, and the power filter caps have been changed to Sprague, and Mallory 150 for the tone caps. I do not know right now anything else, and if the caps are all still in good shape, or if it is properly biased, etc. It's speakers are Eminence from 1967. The 67 in the code, is the code for Eminence, and that the speakers may be from 1969 based on the rest of the stamp on the speakers. So, though I will stipulate with the repair guy not to swap anything out without asking, it will not take a hit in value if I get some things cleaned up. It also has a pigtail plug installed.

The power tubes are Tung Sol 6L6WGB and are quiet. I think they are good. The pre-amp tubes are tung sol as well, I believe. Though I need to check a couple. As I said, they might be bad. But not sure after reading the replies here.

So, all in all, I think a good general check up, including any needed biasing, fixing, tube-replacing, etc. is in order. I have had the thing now nearly 8 years and done nothing to it but play it. Time for some upkeep.

Power tubes
IMG_6771.jpg


Pre-amp tubes, current condition
IMG_6770.JPG


Overall view of back
P1010016_zpsydtmudhf.jpg

Output transformer
P1010013_zpsaxha8l1y-1.jpg
 
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Front view.

IMG_1600_zpsettkmmcr.jpg


When it is running well, which it has always done until just lately, it can do this sound.



It can also snarl too.

Time to get it fixed up!
 
Well, that only took until now to finally get done. I took it down to a recommended guy in Twin Falls (1.5 hour drive) who is, or at least has been, Fender certified. He went through it and gave me the following news.

1). Whoever went through the amp did a very nice job using good parts, capacitors, solder technique, etc. The amp overall is in very good shape and will give years of service.

2). Despite the good solder technique, the problem was a solder joint servicing one of the pre-amp tubes. He had to spend some time finding it, but did. Fixed it right up and the amp is running like a champ he says. One pre-amp tube is a little microphonic, but ok. Wouldn't hurt to replace it. And probably will just do the set. Need to decide who to buy those from. I am guessing a matched set would be a good investment as long as I am getting them.

Should be able to pick it up sometime this week maybe. Excited to get it back!
 
Clarification, it only took a long time because I had had a hard time finding an opportunity to haul the amp down there when he was open, since I posted the thread. He was very quick and professional.
 
Guess who’s home??

dae308cd9c39194de723fd47ebd094a7.jpg


She had to have repaired a “broken connection at V3 cathode bypass capacitors,” and had her tube sockets and pins cleaned and tested.

Just tested everything out and sounds great! Even seems to like my Little Big Muff now. Must have been the failing connection that made them not get along. Missed this amp. Nice to have it up and running.

He emphasized again what a nice job the person did recapping everything and doing everything needed to modernize it when the output transformer was replaced. Due to be replaced transformer, I guess it will never fetch full original dollars like a fully original one would. But I don’t care, it sounds awesome with the Mercury Magnetics FO50BM-2 '59 Tweed style OT and is a stronger amp then a fully original one would be. He said one pre-amp tube was a little microphonic, but that it was not bothering anything. If it acts up, I can replace it. Just a 12Ax7. No big deal.

It seems louder than I remember too. Yay!
 
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