Author Topic: old tube radio exploded in a weird way, what happend ??  (Read 270 times)

Offline e21baur

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old tube radio exploded in a weird way, what happend ??
« on: January 31, 2018, 08:57:50 AM »
2 months ago, was doing this old Nordmende carmen 57 radio... all was working said the former owner, it was mint.... no dust, seem like factory fresh inside...

so here is the question.... did some cleaning at the tubes... and then turned it on.... i head this loud BUZZZZ sound from... the transformator... janked out the powercord.... put it in again... and this buzzz sound for 3-4 seconds and then BLAM !!!!! huge ball of spark/plasma out of the powerchord socket.
Fuses blown in apartment. fuses at radio is complete.

so what happend? seems like the powerchord socket is blown, did i put it upside down in wall outlet socket or did my ... ehrm spraycleaning blew the radio??


Offline bmwr75

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Re: old tube radio exploded in a weird way, what happend ??
« Reply #1 on: January 31, 2018, 09:03:57 AM »
Probably a capacitor failed.
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Offline vpgh

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Re: old tube radio exploded in a weird way, what happend ??
« Reply #2 on: January 31, 2018, 09:07:23 AM »
Any kind of old electronics equipment, especially tube, MUST be serviced before using.
In this particular case, power capacitor might be shorted, that might fault of the power transformer also.

Offline Sir Thrift-a-Lot

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Re: old tube radio exploded in a weird way, what happend ??
« Reply #3 on: January 31, 2018, 12:00:22 PM »

Fuses blown in apartment. fuses at radio is complete.


The first thing I would check is for frayed wires shorting at the plug.   Those old plugs weren't molded, it was copper strands to screws.   One or two frayed strands shorting out power at the socket would certainly do what you describe.   Then work your way through the power source.   Check for shorts at the point of entry.   Check for shorts at the transformer.   If you have a multimeter, first check for continuity at the plug, then proceed as described.

Offline e21baur

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Re: old tube radio exploded in a weird way, what happend ??
« Reply #4 on: February 02, 2018, 04:31:11 PM »
checked the power chord... wow.... seems like explosion come from inside of the plug.... tucked it away, not touching old tube radios anymore after reading about horror storys about high voltage... better let a qualified repair man check out unit :)

Offline Sir Thrift-a-Lot

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Re: old tube radio exploded in a weird way, what happend ??
« Reply #5 on: February 02, 2018, 04:45:30 PM »
You always have to check those before plugging in.   The good thing is that a short there likely didn't harm the amp.   You do know not to power on a tube amp without a load, right?