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REQUIRED VEIWING

Posted: Mon Sep 23, 2013 1:05 pm
by Thom
http://www.youtube.com/watch?v=PLs7p0_1w8U This video should be referred to as required viewing to anyone who even thinks it is ok to plug in vintage equipment without having it first restored to proper operating condition by a professional, knowledgeable in the task. This fella could have lost his home... or worse. Site Administrator, Is it possible to make this a sticky? (Done! Joe_DS)

Re: REQUIRED VEIWING

Posted: Mon Sep 23, 2013 6:02 pm
by MattTech
The video looks like yet another slop-job done by some amateur wannabe tinkerer that read about the famous "cap replacement" that's all-the-rage these days.
It's sad to see, and more dangerous than people think.

The wooden cabinet beneath that charred amplifier could have ignited and caught fire - resulting in a house fire!

I've seen charred amps come in the shop and just shake my head.
One guy insisted on bringing in his Magnavox console's 94-03 amp for me to (properly) re-cap, which I did, and of course fully tested.
His uneducated and careless re-installation of it resulted in a massive burn-out of my hard-earned labor.
Why? - he apparently bridged/shorted the 6.3 volt pilot lamp connectors when reinstalling, and fried the wiring, transformer, and underchassis components.
All blackened up, real nice!

I hate to sound self-righteous, but people need to leave stuff like this to someone knowlegeable, and stop with this highly annoying "I'll fix it from the internet" crap.
They just don't have the finer understanding it takes to do the job properly.
It just reinforces my belief of that often-ignored label placed on electronics...

"WARNING! - NO USER SERVICEABLE PARTS INSIDE - PLEASE REFER SERVICING TO QUALIFIED SERVICE PERSONEL!"

Re: REQUIRED VEIWING

Posted: Tue Sep 24, 2013 1:43 pm
by ami-man
Looking at this video, you can see the latch up of all those caps and the poor installation.

Yes components need to be replaced because of the age of a amplifier or power supply but it should be undertaken correctly it is not only capacitors that need replacing.

Looking at that video they would have been better off just leaving it as original rather than making it a fire risk.

Regards
Alan

Alan Hood
ami-man
UK

Re: REQUIRED VEIWING

Posted: Wed Sep 25, 2013 10:11 am
by Rob-NYC
It should never have gotten to that point..and would not have had the unit been properly fused.

One of the most damning indictments of older American manufacturing practice was the "cost efficiency" phase in engineering.

The designers often made a decent product but it was damaged at the counting stage.

Cheaper capacitors. Cheaper resistors. NO fusing.

I was at the Philadelphia jukebox show back in 1992. I walked by a Seeburg AY . The owner was blabbing to someone and I casually told him "you have a smoking transformer" I could tell by the smell.

Sure enough when he opened the back the main tran was bubbling and ruined. Of all the juke makers, Seeburg was the most "frugal" with fusing. Naturally, nothing had been rebuilt. He asked me to "take it for $75" and I declined. He then went to $50...we made room for it in the van.

The machine was a nice original and really needed only thorough washing and rebuilding. I had it rebuilt and lightly modded in three days. My antique dealer gave me $1300 when he sold it.

Rob

Re: REQUIRED VEIWING

Posted: Wed Sep 25, 2013 12:21 pm
by MattTech
As Rob mentioned, cost-cutting and proper safety measures were a common thing years ago.
One thing I do during restorations is add a fuse to the mains for added peace of mind.
This particularly goes for transformer-powered sets.
The added cost is so minimal, so why not protect the investment?

Re: REQUIRED VEIWING

Posted: Sun Oct 06, 2013 5:28 am
by Record-changer
I have seen only four bad transformers in my life.

One was on a nearly new Rotel amp. One coil had opened due to bad manufacture. The wire had fallen out of the transformer case.

Another was on a strange RCA compact stereo where the power transformer for the amp was in the record changer motor. I had to fix three of these by replacing the motor. One had an open secondary. The transformer was fine in the other two, but the rotor had seized so hard that the entire bearing assembly needed replacement. But they only way to get that was order a new motor. I used a Dremel tool to cut off the seized rotor assembly, and then put the new rotor assembly on the existing coil assembly.

On this unit, the motor ran when the radio was on. You put the drive in N to stop the turntable. On one of the seized units, a coke had been spilled under the turntable platter, and the owner didn't notice any damage at the time.

The last one was a Peavey guitar amp with 6L6 output tubes. The owner was hired to play an outdoor gig, and continued playing after it started to rain. Suddenly flames started shooting out of the amp.

Both the power transformer and the output transformer were fried, and some of the circuit board traces were shorted together by carbonized fiberglass. I was able to order parts and get it going for less than the price of a replacement amp. Yes, there WAS a fuse in the primary of the power transformer. The secondary had a shorted turn, and the primary of the output transformer was open on one side.

Note that, once the transformer starts drawing too much current, the primary fuse protects the owner from fire, but the transformer is usually already gone. Usually a shorted turn in the secondary is the cause. And in many cases, this is due to failure of the winding insulation from vibration, not a shorted capacitor.

Re: REQUIRED VEIWING

Posted: Fri Nov 15, 2013 6:27 am
by MattTech
Well folks, yet AGAIN I have to replace several tubes, along with a FRIED output transformer in a vintage Philco radio-phono console.
I believe this is the 5th restoration this year that I've done with fried transformers.
Virtually the whole audio section and power supply is in dire need of re-working now to get this set up and running properly.

This amounts to added labor time, and of course parts costs that needn't have happened, if the prior owner didn't expect a 50+ year old console to operate into the next millenium.

I really hate to charge the high added costs involved in these situations, but I've no choice. - it's the only way this console will operate again.

Please, people, if you've got a vintage radio or phono, enlist the services of a good restoration tech ASAP, and absolutely avoid using the set in its present (unrestored) condition.
I know, I know, it lights up and sounds ok to you now - BUT - you're playing with a ticking time bomb, trust me.
And for those so-called wannabe teckies - it's NOT just a well-publicized "re-cap" job.
This console's output tube bias was upset by aged resistors, as well as leaking capacitors - causing the tubes to run into redplating and ultimate destruction of the (now difficult to find/replace)output transformer, along with causing power supply issues.

-Matttech.