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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 14th Sep 2018, 2:26 pm   #1
Glowing Bits!
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Default 50C5 valve with a strange fault.

This would be a simple question but is likely to end up long and winded, what a surprise!
I'm nearing completion on an American GE set but have come across an issue with the above output valve when running it on the valve tester.
The first fault I found was that pins 2 & 5 (both internally connected to G1) seem to be operating the heater, as is pin 4 which is the correct pin for the heater, is this normal?
The other thing I couldn't help noticing was the fact that there appears to be some form of electrical leakage between the anode and cathode, this would usually be a bad sign at the best of times.
Would this render the valve scrap?
I don't fancy the idea of having 50v ac as opposed to the usual negative voltage driving the grid!

Any help/advice greatfully appreciated.

Regards, Rick.
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Old 14th Sep 2018, 2:45 pm   #2
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Default Re: 50C5 valve with a strange fault.

Are the heater connections correct, 5&3 mixed up?

Lawrence.
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Old 14th Sep 2018, 2:52 pm   #3
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Default Re: 50C5 valve with a strange fault.

Are the marking clear that it is a 50C5?

The structure inside of a 50C5 is very easy to see, can you establish that the pins are connected to where they should be?

If it is a faulty valve something quite horrible has happened to it.
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Old 14th Sep 2018, 2:52 pm   #4
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Default Re: 50C5 valve with a strange fault.

Are the leaks in the valve or valve holder?
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Old 14th Sep 2018, 3:40 pm   #5
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Default Re: 50C5 valve with a strange fault.

Thanks for the replies so far, the usual pins of 3 & 4 are working correctly for heating the valve, the filament return on the machine is to pin 3, pins 2 & 5 should not be connected to anything other than G1, but the valve still glows on these pins.
Another valve has been used on the machine to verify that the holder is working as it should.
When lightly (with finger only) tapping the valve whilst holding it (no test gear needed), there is a slight movement sound, I'm now wondering if the valve has had a bang at one time but not enough to break it.

All of this is more of a curiousity if anything, these are available on a well known auction site if need be.

Rick.
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Old 14th Sep 2018, 3:44 pm   #6
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Default Re: 50C5 valve with a strange fault.

Sounds terminal.

Lawrence.
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