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Old 27th Jun 2020, 12:04 pm   #1
John G8MWF
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Default GEC 5639 Tone Correction Capacitors.

Does anyone know the working voltages of the tone correction capacitors C21 & C22?

Something in the back of my mind says they should be higher than 'normal' and I would like to get hold of them before fitting them!

The ones in my set are very black and impossible to read - see picture.

My set is missing the bottom cover and, if possible, I would also really appreciate a picture of what the original cover looks like.

Kind regards

John
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Old 27th Jun 2020, 12:13 pm   #2
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Default Re: GEC 5639 Tone Caps

Can you please explain "Tone caps" ?
I can see three new electrolytics rather poorly fitted. I don't know what "tone" caps you may be asking about.
There is ONE sad looking paper waxy that I would remove on sight. That's about all I can see.
Joe
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Old 27th Jun 2020, 12:31 pm   #3
Station X
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Default Re: GEC 5639 Tone Correction Capacitors.

The OP meant Tone Correction Capacitors.

Thread title updated.
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Old 27th Jun 2020, 12:36 pm   #4
marconi_pete
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Default Re: GEC 5639 Tone Correction Capacitors.

Just had a glance at the service sheet for the GEC BC5639. C21 is a 0.0015uf cap and C22 is 0.05uf cap. Theres no working voltage rating given on the trader sheet but as they're both waxies I'd just replace them them with 630v axial poly caps. You could possibly get away with 400v rated caps in those positions but would recommend going with 630v to be on the safe side.

Thanks,
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Old 27th Jun 2020, 12:38 pm   #5
poppydog
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Default Re: GEC 5639 Tone Caps

Quote:
Originally Posted by joebog1 View Post
Can you please explain "Tone caps" ?
I can see three new electrolytics rather poorly fitted. I don't know what "tone" caps you may be asking about.
There is ONE sad looking paper waxy that I would remove on sight. That's about all I can see.
Joe
How are the elec caps poorly fitted??

poppydog
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Old 27th Jun 2020, 12:39 pm   #6
paulsherwin
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Default Re: GEC 5639 Tone Correction Capacitors.

The tone correction cap across the output transformer primary is normally rated at 1kV, though you can probably get away with a lower rating if using modern plastic film caps with self healing characteristics. Other tone caps just need to be rated at the HT voltage.
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Old 27th Jun 2020, 12:59 pm   #7
ms660
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Default Re: GEC 5639 Tone Correction Capacitors.

Don't forget to disconnect the original HT filter capacitor if those new ones are to be left in circuit.

The HT filter resistor looks as though it's had a hard life at some point.

Lawrence.

Last edited by ms660; 27th Jun 2020 at 1:20 pm. Reason: correction
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Old 27th Jun 2020, 1:09 pm   #8
crackle
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Default Re: GEC 5639 Tone Caps

Quote:
Originally Posted by poppydog View Post
Quote:
Originally Posted by joebog1 View Post
Can you please explain "Tone caps" ?
I can see three new electrolytics rather poorly fitted. I don't know what "tone" caps you may be asking about.
There is ONE sad looking paper waxy that I would remove on sight. That's about all I can see.
Joe
How are the elec caps poorly fitted??

poppydog
Two heavy electrolytic capacitors hanging on to a single pair of wires is asking for the solder joints to fail.
I would solder each capacitor direct to the solder tags, and strap the caps together to help stop them vibrating. I would also strap the single capacitor down as well to stop it vibrating and breaking the wires or cracking the solder..
Mike
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Old 27th Jun 2020, 2:24 pm   #9
cathoderay57
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Default Re: GEC 5639 Tone Correction Capacitors.

I'd also strongly recommend slipping on some red sleeving to cover the live wires to the replacement caps - otherwise, it's all too easy to get a belt when you are poking about with meter probes etc.
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Old 27th Jun 2020, 2:27 pm   #10
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Default Re: GEC 5639 Tone Correction Capacitors.

Certainly a 1000V as stated or even 1500 V across the primary output transformer.
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