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Old 22nd September 2012, 05:23 PM   #1
Truth is offline Truth  Sweden
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Exclamation Help! Did my power cable blow his tubes?

I sent my DIY power cable to someone, it has worked perfectly for months in my system. He plugged it into his tube amp and the aftermarket fuse blew in his $10,000 amp. He switched to his old power cable and his tubes blew, and another fuse. The fuses and tubes are worth $641, and he wants me to pay for them. Because he hasn't had any problems for 3 years, until switching the power cord to mine.

Is it possible that a power cable can do this?
 
Old 22nd September 2012, 05:35 PM   #2
jrenkin is offline jrenkin  United States
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I can't imagine how. A power cable really only could fail by being open or being shorted. If it were open, nothing would happen. If it were shorted, it would be a short BEFORE the amp fuse and of course any amp circuits. That might spark and burn and blow a HOUSE CIRCUIT breaker or fuse, but not the amp's. Besides, it happened again with his cord. Does your cord still work in your equipment?
 
Old 22nd September 2012, 05:38 PM   #3
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If it is wired correctly - it can't.

Possibilities I can think of:

* live-neutral reversed (only makes sense if you live in a country with polarized plugs)

* earth disconnected (may have an influence if the device relies on it)

* earth-live/neutral reversed (the most dangerous way of misconfiguring a power cable)

Most of these misconfigurations should already have shown some effect in your own system. And, it should be a really simple DMM job do measure the power cable in question and check its configuration. If it measures ok, the fault in his amp has no connection to your power cable.

Greetings,
Andreas

PS. Many tubes, unobtainium tubes or snake-oil tubes worth $641?
 
Old 22nd September 2012, 05:39 PM   #4
Truth is offline Truth  Sweden
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Quote:
Originally Posted by jrenkin View Post
I can't imagine how. A power cable really only could fail by being open or being shorted. If it were open, nothing would happen. If it were shorted, it would be a short BEFORE the amp fuse and of course any amp circuits. That might spark and burn and blow a HOUSE CIRCUIT breaker or fuse, but not the amp's. Besides, it happened again with his cord. Does your cord still work in your equipment?
I have not tested the cord in my system yet, he lives on the other side of the world. Should I let him send the cable back to me so I can test it?
 
Old 22nd September 2012, 05:39 PM   #5
M Gregg is offline M Gregg  United Kingdom
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Interesting,

NB the aftermarket fuse blew???
On what?
Couldn't be the power to a transformer supplying the bias could it?

After market problem waiting to happen?
Did his power cord have a gnd? If not and yours did..

As above if all connections and polarity are correct then whats the difference with a standard cable?

Only my thoughts...

Regards
M. Gregg
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Old 22nd September 2012, 05:54 PM   #6
Truth is offline Truth  Sweden
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I always triple check everything when building the power cables. I use CE certified AC wiring with color coded conductors and grounding. I wire them into Furutech AC plugs that have color coded screws. I think it's nearly impossible I wired the live and neutral reversed. But it's also a strange coincidence for him that plugged in my power cord. How could this happen? Physical shock to the tubes when switching the power cord?
 
Old 22nd September 2012, 05:56 PM   #7
M Gregg is offline M Gregg  United Kingdom
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If this claim is being made,

Ask how this happened with a tech report because I think its going to be a hard job to prove this has happened..

Post the report here lets see what has happened..The snake oil won't wash here..
If the equipment has failed unsafe then why has it failed unsafe ie faults to the system or bad protection?
Ask what is wrong with the cable..what fault..do you trust it not to be tampered with?
Remember its your call we can only give ideas the rest is up to you..
Even if the live and Gnd were reversed then how will the power Tx turn on..there is no connection between live and Gnd or neutral and Gnd in the amp so how have the heaters or HT (B+) been on for this to happen?
OK the chassis would become live and could Kill someone, however how does the power Tx turn on?
Possible neutral and Gnd in wrong connection..so power to Tx system should still run with neutral on chassis...even then how does this destroy tubes?
No further comment..

Regards
M. Gregg
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Last edited by M Gregg; 22nd September 2012 at 06:11 PM.
 
Old 22nd September 2012, 06:07 PM   #8
DF96 is offline DF96  England
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Would you trust someone who believes in power cables, aftermarket fuses and $10,000 amplifiers and then blames a power cable for what is clearly a coincidental amplifier fault?

PS Just thought of a sensible reason: your cable plugged him in to a doubled supply? I'm thinking of the American habit of having 110V for most items but 220V for power hungry ones. Even if that happened, it is his fault for not checking things like plug type on the end and transformer primary taps on the amplifier.

Last edited by DF96; 22nd September 2012 at 06:10 PM. Reason: add PS
 
Old 22nd September 2012, 06:34 PM   #9
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How do you "blow a tube"? A cold tube that is.
I would imagine your "customer" to move his amp around, and damage something.

If there is a chance of giving the transformer twice the voltage it requires, I would expect there to be a fuse that blows before a damage like an open circuit filament happens.
Is the afermarket fuse a proper fuse, does it have the correct value and characteristic?
 
Old 22nd September 2012, 06:34 PM   #10
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Quote:
Originally Posted by Truth View Post
I sent my DIY power cable to someone, it has worked perfectly for months in my system. He plugged it into his tube amp and the aftermarket fuse blew in his $10,000 amp. He switched to his old power cable and his tubes blew, and another fuse. The fuses and tubes are worth $641, and he wants me to pay for them. Because he hasn't had any problems for 3 years, until switching the power cord to mine.

Is it possible that a power cable can do this?
Where does the person live that you sent the power cable to?
 

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