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Question for owner of Fender amps


One-armed Alec

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Specifically those who own amps with the 'Tweed' style of cabinet, where the controls are at the back of the amp - e.g. the Blues Junior, Bassman, Tweed Twin.

 

I've just bought a Vintage Reissue '57 Twin. I'm not very familiar with this style of amp and am concerned about two things:

 

* When looking down at the top of the amp, there is a 5mm gap between the back of the chrome control panel and the wooden panel that fits to the back of the amp. It's big enough that I can see the wires inside the chassis. Is it normal to have a gap like this?

 

* I can see from looking through the above gap that there is no kind of 'lid' or 'panel' on the back of the chassis. In other words, if I were to remove the wooden panel at the back of the amp (say, to change a tube), I'd be looking right into the insides of the chassis. This just seems a wee bit dangerous. From what I understand, you can kill yourself just by touching the wrong component inside a tube amp, even after it's been powered down for ages. Is this normal, shouldn't there be a metal cover on the back of the chassis?

 

:confused:

 

I'd be grateful if anyone could enlighten me!

 

Many thanks.

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Originally posted by
JC777

Just looked at a picture online. Does it look like the panel may have warped or maybe it's bowed from humidity?

Hey man - thanks for the reply.

 

The panel itself looks fine - it's not warped or anything - it's more like the chassis has been mounted too far in. Either that, or the chassis should have a metal cover on the back...!

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Some amps will develop a small gap. It could also be due to being dirty but mostly, your probably going to have to deal with it. It would be nice if you could post a pic to show the extent of the problem. I would say, it happens.

About the chasis, there should be no metal cover. You can change the tubes without removing the back panel but its easier to take it off. (sometimes) What protects the circuit is the back panel and thats it. To reduce any RF interference they use a kind of metal foil on the back cover. As long as you dont stick you hands in there you should be fine. If you're really paranoid then what you can do is reduce the voltage that is held in the caps by partially draining them.

Turn the amp on, let it warm for a min, turn the standby off to where you are in playing position. Unplug the amp (yes, while its on) and let it fade out. Now leave the switches where they are at. Bboth in the "on"/operating position. Remove the back panel and change the tubes. (respectably when they are not hot). Place the back panel back on. turn both switches to the "off"/shutdown position. Plug her up and just use it like normal. That should drain the caps to like 3-6 volts. (or at least in my HRD it does).

If you have any more questions dont be afraid to ask.

:wave:

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Interesting to see this old thread again..... Boy have I learned a lot about tweed amps since I posted this question!

The Fender Tweed Twin went back to the shop on account of the incorrectly-mounted chassis (which was the cause of the excessive gap between it and the rear panel), and also on account of the amp producing loud crackling noises after having been on for more than 20 minutes (tubes were swapped, etc - no joy).

In the end, I ended up buying a Victoria Double Deluxe tweed amp. It's a Fender Tweed Deluxe clone with a twist - it has double the number of power tubes and two speakers rather than one. There is no gap between the chassis and the back panel of the Victoria - it has apparently been put together with some precision! Most importantly, the amp sounds even nicer than the Fender (which itself sounded very nice, to be fair).

On the downside, the Vicky had some teething problems. The power tube sockets were rather loose for the tubes that came with it (JJ 6V6s), there was red glow on the plates of the tubes, and an intermittent crackling noise from the speakers

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I've got a few tweeds; if there is a gap between the chassis and the upper back panel, it should be narrow to the point that light doesn't shine out of it.

I had a baset-case `59 Tremolux re-tweeded a few years back. Midwest Restoration did a great job except the new holes for mounting the chassis were drilled about an 1/8" forward on the front/back axis. This translated to an 1/8" gap when the chassis was in the amp. Light fron the pilot bulb shone bright out of the gap, it looked bad.

Since that was my first restoration project, I decided to drill the mounting holes in the chassis. Fixed the problem at the cost of f'd up holes in the chassis (not visible when the amp is all together). Half the amp is no longer original, so I figured I wasn't doing too much damage.

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Originally posted by
MarkSimpson


I've got a few tweeds; if there is a gap between the chassis and the upper back panel, it should be narrow to the point that light doesn't shine out of it.

Yeah - the gap on the Fender was more like 1/8" at one side and 3/16" at the other. I could look in and see the tops of the tube sockets. It was ex-demo (trade fairs, apparently) and I get the impression it had been chucked about a bit.

 

The panel fit on the Victoria is perfect. However, I have to watch how tightly I screw it back in. Too far and it can vibrate against the chassis.

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Originally posted by One-armed Alec

Yeah - the gap on the Fender was more like 1/8" at one side and 3/16" at the other. I could look in and see the tops of the tube sockets. It was ex-demo (trade fairs, apparently) and I get the impression it had been chucked about a bit.


The panel fit on the Victoria is perfect. However, I have to watch how tightly I screw it back in. Too far and it can vibrate against the chassis.

 

 

I don't see how an amp getting banged around can cause the gap - if anything, I'm guessing the amp came off the line that way, a bunch of folks in the shop looked at it until a light bulb appeared and someone said "hey, let's send this one to the trade fair."

 

As far as your Vicky goes - maybe a bit of thin foam tape where the back panel meets the metal edge of the chassis?

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Originally posted by
MarkSimpson


I don't see how an amp getting banged around can cause the gap - if anything, I'm guessing the amp came off the line that way, a bunch of folks in the shop looked at it until a light bulb appeared and someone said "hey, let's send this one to the trade fair."

Possible - but the chassis was twisted in such a way that the back panel screws had stripped from the cabinet (the bottom of the chassis was pushing the back panel out). I find it hard to believe that they'd have let it out of the factory in that condition - isn't very good publicity for them at the trade fair!

But who knows ;).

Originally posted by
MarkSimpson


As far as your Vicky goes - maybe a bit of thin foam tape where the back panel meets the metal edge of the chassis?


It isn't causing me a problem right now - it's OK if the screws are set just so - but thanks for the useful tip.

:thu:

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