Tube Amp Technical Help Request

[jasonbruce]

Hi guys - this one is a plea for advice from all the amp gurus out there.

I recently got my hands on an old tube amplifier from the US (and when I say old, I mean it's OLD, like early 1960s). I just wanted it for THAT sound which I'd heard once long ago during an earlier visit there.

Here's where the trouble begins. When it arrived, I plugged it into the wall socket and turned it on. (At this point, I know all the amp-heads out there are gonna be clucking their tongues in disapproval). Next thing you know, the operation light turns on for a second, then goes dead. Sound-wise, nothing. Nada. Zip. Zero.

Here's my question then.... What the hell do I do now? Is it beyond repair? Is it likely that the different voltage here killed the transformer (difficult to replace) or just blew a fuse?

Second question, what should I have done? Use a variac to ease the old lady into action first? Go to standby first (note however, this particular unit did not have a standby switch, but for future amps, should that be the way?)

Anyhow, as you can see, amps, tramps, schlamps. I'm no amp guru.

Would be grateful for any sagely advice you guys can give me. And in the interest of saving bandwidth, would be grateful if we save this thread for those who can offer some technical advice please.

Truckloads of thanks in advance.

 

[chimaera]

URMM.... is it because the amp was rated for 110V and well Singapore is 220V...??? If that is the case it could be an expensive fix...

 

[jasonbruce]

Yup, that's what I was referring to when I mentioned the different voltages.
Dammit, why did I get so careless.

 

[chimaera]

Urm blown transformer perhaps ? Randolf/Mikemann should be able to help...

 

[leecs]

go to randolf@embryosongs.com. the amp might & might not get fixed because the transformer inside has blown & diffcult to get the same 1.

Got any 'chau ta' smell once the thing is blown?

 

[ChanMin]

haizz i did the same thing to my Budda ZenDrive....

 

[jasonbruce]

Yes, I fear it may be the transformer too. Replacements will be hard to come by, but not impossible.

Anyone know how Randolf works? I guess I bring it to his place to check it out?

ChanMin - so what did you end up doing with the Budda?

Thanks.

 

[roslih]

Have u checked the fuse ? I'm sure it's the one to go first. If it is just the transformer, it shud not be dat difficult to deal with. Just get it changed to a 240V and you permanently fix this.

 

[embryo]

Hi, sorry to hear about your plight. Hopefully I can be of service. I was told about to check out your problem here and offer some tips.

It seems to me there's quite...or rather more than a few here with pretty similar problems especially with the popularity of acquiring overseas stuff thru ebay. Chan Mins pedal for example has quite an extensive problem throughout the circuit including a blown transformer. I've also been workin on an old mid 60's Gibson amp that originally had a blown transformer which was eventually replaced with a similar spec but you noe wat... more stuff throughout the amp keeps blowing up[ over time. I'm just hopeing the speakers hold up long enuff.
I've also got a mid 90's H&K Triamp from the US that has the power supply and output section blown ...charred even. I'm probaly mad to entertain the idea of reviving it from the grave.... given time I guess I will.

Here's what you can do. Replace the fuse usually located near the power cable that's going into the amp. Chances are there'll also be a red power lamp that's also gonna get blown. If the fuse was originally fitted with a slo blo type you could at worst also blow the rectifier which is inside the amp. Modern amps usually have another fuse nesr the rectifier circuit. If it's blown make sure it's replaced with an exact spec'd fuse otherwise.... the power transformer could be blown too but this only happens with....errrr very very old tube amp designs. Ouch!
Ok the very worst that can happen is really having the power transformer blown and that's where the old "mojo" begins actually.

My advice for reeely old tube amps is if you are really looking to buy, own and use one make sure you are prepared to sustain a whole lotta mooolah needed to service, revive and maintain it running in it's intended working state.

Keep fingers crossed. Best of luck dude.

If anything else email me at randolf@embrysongs.com

 

[jasonbruce]

Hey guys - a truckload of thanks for the advice.

A quick update: I snapped out of my woe-betide-me phase long enough to decide that I would try to solve this problem for myself. So thanks to some checking with Mr Fliegler (an amp guru whose books I'd forgotten I had!), it was clear it was either the fuse or the transformer.

So fingers crossed, I dug up the schematics on the net (not easy for such an old lady*) and found it needed a 1 amp rated fuse. Tracked one down (in Raffles Place no less!) and voila! Problem solved! Good thing the transformer's still fine, thanks to the fuse. (Two days ago, I had actually even managed to track down a vintage replacement transformer, and was ready to buy it online before this stroke of good fortune.)

Again, thanks for the advice, especially from Randolf above.

And by the way, it was all worth it!!! Without hyperbole...this amp doesn't have good tone. THIS AMP IS TONE!

----------
* refers to the amp, not me.

 

[Ratboy]

remember to unplug amp + drain the power caps before you do any circuit surgery

 

[faizal_rocks]

Hi guys

I just checked out this thread n I`m getting some concerns as well. I`m in the midst of getting an Epi VJ head from Ebay thats rated at 115V. So the 1st thing when it reaches here, I don't plug it in yet? I must change a component or something in order to support our local voltage here? Hope u guys can advice. Thanks.

 

[MackSonne]

Gawd Jason do give us some sound clips if you have the time!

 

[Ratboy]

Hi guys

I just checked out this thread n I`m getting some concerns as well. I`m in the midst of getting an Epi VJ head from Ebay thats rated at 115V. So the 1st thing when it reaches here, I don't plug it in yet? I must change a component or something in order to support our local voltage here? Hope u guys can advice. Thanks.

If you want to just check the amp in it's "original condition"
just get a huge step down transformer
so step down the local voltage 240 > 110
and you can test the gear.

All who import electronics from USA should have a nice big one to do basic testing
say 1000watts should work

 

[Indigo_blues]

Congrats on the amp fix.

What amp is it btw? I like old tube amps also so I'm curious to know..

 

[jasonbruce]

Faizal:

That's right, you need a step-down transformer. You can get one from most DIY places, but if it's your first experience with one of these I'd suggest getting the salesguy there to show you how to use it. It's important that you get the input and output settings right. Mix that up and you'll be getting a step-up instead of a step-down! Also check the wattage on your gear cos different voltage transformers have different wattage limits. Mine is a 150W one cos I also use it to run a 125W Gretsch Super Bass Head.

 

[jasonbruce]

IndigoB - Thanks. As to your question, let me be a little cryptic. ;-) It's from an old American department store.

MacSonne - Plans are underway...

 

[faizal_rocks]

Thanks for the reply, folks