Have I blown my amp

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Ben79
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Have I blown my amp

Post by Ben79 »

Did my first cap job on an old 60s valve amp I picked up for £45 on Gumtree.

Thinking the black wire that had been attached to the filter caps' negative lead was a ground wire, I just soldered it on to the twisted negative leads of the 2 new caps and left it at that. Turned the amp on and nothing happened. Realised today that the black wire came from the PT and it needed an extra wire to ground so I soldered one on, powered it up, and on came the rectifier tube but no glowing from the ef86 or the el84.

When I powered up the amp without the filter cap grounds connected, did I run AC through the circuit and destroy everything?

It's a Bird Talisman btw....

http://www.vintagehofner.co.uk/britamps/birdy/talisman.html
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tuffteef
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Re: Have I blown my amp

Post by tuffteef »

i dont think so the filter caps would be post rectifier so it would be dc by then just like super ripply
i may have to think about this though :idk:
have u found a schem at all?
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osbornkt
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Re: Have I blown my amp

Post by osbornkt »

From what I've been told about filter cap changes, if you wire them in incorrectly it only damages the caps and not the amp.
Think you should be fine.
Just probably need to buy another new filter and put it in. Check everything else with your multimeter coming off that particular cap as well to make sure those parts weren't damaged in the process.
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Ben79
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Re: Have I blown my amp

Post by Ben79 »

have u found a schem at all?


Yes...most of one.

http://www.vintagehofner.co.uk/britamps ... ali4a.jpeg
Last edited by Ben79 on Tue Aug 13, 2013 5:24 pm, edited 2 times in total.
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Ben79
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Re: Have I blown my amp

Post by Ben79 »

another new filter and put it in


Damn, I spent a good 20 minutes soldering those 2 caps in and I've got no more 47uf. Is there a way to check them without a multimeter? Mine only goes up to 2uf.

Another potential issue is that one of the wires cames off the OT while I was working on it. Quite a thin flimsy wire actually. I did my best soldering it back onto what looked like its little metal stump. It stuck, so I presumed it found some kind of connection. Is there an easy way to check the OT with a multimeter?
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Re: Have I blown my amp

Post by Greenfuz »

I dunno anything about this kinda junk but gimme that amp it's beautiful
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Re: Have I blown my amp

Post by Ben79 »

It's only got about 15 components in it, you could build one. And it would be better than this one cos it wouldn't have a 10x6 elliptical gramaphone speaker in it. Actually not a bad amp though. It sort of worked before I started 'repairing' it and like most small valve amps I've used, it liked some fuzz in it. Oh yes.
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Re: Have I blown my amp

Post by Greenfuz »

I've got like 5 different old valve amps I love em


but seriously though the way the grill cloth on that bird wraps around those corners is fuckin HOT


and whatever is goin on in the back with that metal plate? yes please
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Re: Have I blown my amp

Post by Ben79 »

Mine is the less appealing 'picnic basket' design.

http://www.vintagehofner.co.uk/britamps ... tali6.html
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