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FDP Forum / Fender Amps: Vintage (before 1985) / Seriously suspicious

wrnchbndr
Contributing Member
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New Jersey

I'm back with the otters again
Sep 5th, 2018 09:37 AM   Edit   Profile  

I generally don't do amp repairs. But I'm skilled enough for basic troubleshooting of an old '60s Fender. I know a number of guys who have amp repair mojo and I'm not one of them.

A blackface Deluxe Reverb come into the shop to be sold on consignment by a widow -- that is what I'm told. Its missing the fuse cap and it looks like its been in a dusty but not damp basement for ten years.

The fuse holder itself is damaged and I have a replacement on hand. Since I'm doing the fuse holder, I upgrade to a three prong power cord and disconnect the death cap. Inside, everything is totally original. The tubes are vintage made in USA except the two AT7s which are Telefunken. I look it over and I don't see anything wrong so I slide the chassis back into place and slowly power it up with a variac over a one hour period.

The jewel light comes on at about 30VAC, the current draw is low and by the time I get to 110VAC I plug in a guitar. No output, total silence, no smell, and the amp is drawing about .8A. I look in the back and see the rectifier tube lit but none of the other filaments lit so I turn it off and pull the chassis again.

I follow the filament wires from the jewel light to the first 6V6 and find one of the wires disconnected from the tube. Its not broken -- its been desoldered cleanly. The tinned hook on the wire is still there and there is no broken-off wire in the solder filled lug which still has the other green wire in place. It is really clear that this wire has been removed by someone with a soldering iron.

Reconnected the wire, found a dead AT7 - replaced it, the amp powers up drawing 1.5A and everything works. The speaker was slightly distorted for about a minute and it cleaned up and the amp is working 100% -- not even any scratchy pots. Sounds great.

I can't think of any troubleshooting process that would cause a tech to disconnect this one wire. My thoughts are that this was done on purpose to make the amp not work. I've disconnected sections of circuits to troubleshoot but not like this. I find this very fishy. Do you?

Hammond101
Contributing Member
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So. Cal. USA

Sep 5th, 2018 10:42 AM   Edit   Profile  

Yeah that's weird. Guys would engage the reverb pan lock covertly when checking out used Fender reverb units years ago. A rookie sales clerk in a pawn or guitar shop would think the unit needed repair and offer bigger discounts.

Who knows how long ago this wire was disconnected.

BbendFender
Contributing Member
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American Patriot

About as ordinary as you can get.
Sep 6th, 2018 09:25 AM   Edit   Profile  

This would be a good amp to own.

Silverface

Lawndale CA

No Chops but Great Tone ©
Sep 7th, 2018 09:36 PM   Edit   Profile  

Who knows?

But if the amp is all original it needs new filter and bias caps asap. They have a general life expectancy of around 15 years. At this point the amp may work fine but a cap can blow with no warning. This can fry your power transformer.

Most vintage Fenders I service have not been properly serviced, simply because most players aren't aware they need a periodic checkup - check voltages, clean and lube pots, jacks and tube sockets and replace significantly out of spec parts. This, with filter/bias cap replacement , is normal maintenance.

Also, if an amp has been stored for an extended period it's even more critical. Electrolytics crystallize if the amp isn't fired up periodically and they are even more prone to failure.

I'd get that work done right away. If the caps are the originals and it was mine I wouldn't even turn it on until it's serviced. Power transformer replacement is expensive and also reduces vintage value. I've replaced enough of them I'd be concerned..

Peegoo
Contributing Member
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Head down, ears back

Headed for the bar
Sep 7th, 2018 10:27 PM   Edit   Profile  

Depends on the buyer.

Some want all original (or as close as possible), play it, and take the risk of having it blow a gasket.

Some buyers have no intention of even plugging it in. They want to admire it and dust it.

And some will want it in racing trim, ready to do gigs and be a reliable player.

Roly
Contributing Member
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Whitehorse Canada

I don't get out much
Sep 8th, 2018 05:07 AM   Edit   Profile  

"If the caps are the originals and it was mine I wouldn't even turn it on until it's serviced."


+1

wrnchbndr
Contributing Member
**********
**

New Jersey

I'm back with the otters again
Sep 10th, 2018 09:38 AM   Edit   Profile  

It ain't mine and leaving it alone is the winning strategy to make it appealing to the widest range of potential buyers. At this point, it can be left alone or it can be serviced. I question my decision to upgrade the power cord but when I do, I save the original cord and all of the wires to allow it to be returned to it's original configuration. But it won't be my failure to update this safety issue if somebody plugs it into the wall and dies.

FDP Forum / Fender Amps: Vintage (before 1985) / Seriously suspicious




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