Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: mresistor on January 09, 2018, 04:19:23 pm
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I've got an '04 Fender Blues Deluxe Reissue on the bench and this is the first time I've ever seen this problem. I let the amp warm up for a bit and then take it off standby and it has brutal arcing sound for about 1/2 a second, Since I have the back off, I cycle the standby switch again and I can see the 47uf e cap is arcing at the joint of the negative lead to the end of the cap.
Has anyone ever seen this before? I wonder if it is just a bad cap or something else. Is it ok to solder a lead back to the negative end of the body of an e cap?
The cap is an F&T as someone has been in this amp before and it looks good. They lifted the sand cast resistors to keep from burning the board, etc.
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probably a bad solder joint. remove old solder and flow new solder.
--pete
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Thanks Pete I'll give it a go.
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Well the solder won't take to the end of the cap which I think is aluminum. So it needs new cap. Has anyone ever desoldered and resoldered a main filter cap in a Fender Blues Deluxe reissue from the front side of the board?
(the negative lead broke off right where it meets the body of the cap. )
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Has anyone ever desoldered and resoldered a main filter cap in a Fender Blues Deluxe reissue from the front side of the board?
I would not do that. No telling what may get damaged on the other side of the board.
Are you just trying to avoid the tedious job of pulling the board to do it correctly? If so, just snip the cap leads as close to the cap body as you can. Sounds like you're half way there already. Then solder the new cap leads to the leads that are still connected to the board. Take your time and you can make a neat, secure connection.
I would only do this as an emergency/temporary solution. But I've seen lots of work like this just because the tech was lazy. Many times the work is sloppy to boot.
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Thanks Sluckey,, I know I have to undo all the pots and jacks on the board to flip it over to access the pads on the back ..not being lazy..just asking a question. I've always disassembled the amp to access board backsides. I was interested if anyone ever did it successfullly. There is a bit of pad on the front side of the board for the filter caps. If the pad hole has metalic composition continuous to the backside then the solder heat would be transfered to the back of the board, in both soldering a de-soldering operations. With the use of fluxed desoldering braid and correct heat it might wick the solder from the backside to the fluxed braid on the frontside in the desoldering operation. Then with flux and proper heat it could be resoldered back in. Not good that what happens on backside won't be observable.
Personally, splicing of capacitor leads is tacky and although I could do that I will not. Not even on my amps.
So I guess that is an experiment for another time.
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I probably should have posted this pic to begin with ..
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I did a recap on my blues deluxe with no major problems, you may have just gotten a dud, sadly. I've had great success with those caps (They're what I put in mine, I did a video on it if you want to watch somewhere on my frenchie films channel :D)
~Phil
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Hey Phil I will go check yer vid.. :icon_biggrin: . This is a customers amp and I think someone bent the leads on the cap too much and fractured the lead at the point where it meets the body.. and it started arcing at the point where the metal was fractured after some time of use and lots of vibration.... from what I understand this amp has been gigged weekly for many years.
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Oh yeah, then I'd also suggest trying to bend the leads in more of a gentle 'u' bend instead of a hard angle, found out from one of the guys on facebook that gives the leads room to 'move' better. That and of course use GE Silicone II on that cap so it can't move next time :D
~Phil