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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 24th Jul 2022, 9:06 am   #21
DMcMahon
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Default Re: Grundig TK24 belts location

Rechecked the EL 95 results and unless I am going stupid (hopefully not ) the results are not drawn correctly.

On the valve, pins 1 (G1) and 7 (G1) are internally linked but 0V is shown on pin 1 and 20.7V on pin 7, i.e. pins 1 and 7 should read the same.

181V is shown on pin 2 (Cathode/Grid 3) which is far too high.

202V is shown on pin 3, pin 3 is a heater filament connection so will not have DC voltage on it.

0V is shown on pin 5 (Anode), the anode will have a high HT voltage on it via the output transformer secondary winding.

21V is shown on pin 6 (Grid 2) this is far too low

Please recheck the EL 95 results.

David
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Old 24th Jul 2022, 9:31 am   #22
DMcMahon
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Default Re: Grundig TK24 belts location

To remove the chassis from the case as you know involves disconnecting the loudspeaker wires.

When powering up the chassis when it is out of the case, it is not good to leave the speaker disconnected, so either reconnect the speaker wires or switch in the 20 Ohm dummy speaker load resistor (R48) by pulling up the volume control until you hear its switch click.

David
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Old 6th Nov 2022, 11:43 am   #23
moss999
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Default Re: Grundig TK24 belts location

Hi , sorry ,but this got put at the bottom of a large pile , I think the confusion was I couldn't get to the pins on the bottom so I pulled the valve out slightly and measured from the top and must have drawn them wrong , although I put this back together today and didn't realise the on /off knob is also an internal speaker off ,,,, ...
So it appeared to be working ok , I left it playing for a while but the volume seems to get less and less until nothing over a couple minutes or so .
sorry again for the late reply .
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Old 6th Nov 2022, 1:41 pm   #24
DMcMahon
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Default Re: Grundig TK24 belts location

Does not sound good, does the output transformer get noticeably warm/hot during the volume fading ?

See what happens to the main HT voltage at C31 (as per Post 19) when the volume fades.

David
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Old 7th Nov 2022, 9:36 pm   #25
moss999
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Default Re: Grundig TK24 belts location

Hi , so I removed the chassis again and rigged up the speaker with some extension cables but cannot get it repeat the volume fading issue , had it playing for an hour or so and it appears to be working fine , !
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