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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 11th Nov 2018, 4:22 pm   #1
NorfolkDaveUK
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Default Revox B77 No record left side

I have this B77 .

It's not recording on the left side and the right side record sounds a bit weak. I'm getting signal into the osc on Y-rec, but nothing on H-rec , can someone explain what the Y and H are please and thank you.

David
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Old 11th Nov 2018, 7:02 pm   #2
NorfolkDaveUK
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Default Re: Revox B77 No record left side

Let me start over.

It's the oscillator signal I can see on pin 8 of the oscillator (not adjustable with the record level.

Can someone help me to proceed please.

Thanks.
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Old 11th Nov 2018, 7:12 pm   #3
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Default Re: Revox B77 No record left side

A cursory look at the circuit shows that Y-REC is the input to the record amplifier and H-REC is the output from the record amplifier. I think Y and H are just ways of labelling the points in the circuit and have no other significance.

You need to fault find on the amplifier. As you have two amplifiers ie one per channel checking voltages and signal levels at various points in the amp should be a simple matter of comparison.

Bear in mind that there's a muting circuit at the input to the amplifier and a fault here will kill the output.
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Old 11th Nov 2018, 7:14 pm   #4
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Default Re: Revox B77 No record left side

Probably 'L-REC' is Low (amplitude) RECording signal and 'H-REC' is High (amplitude) RECording signal.
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Old 11th Nov 2018, 7:15 pm   #5
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Default Re: Revox B77 No record left side

OK . I have now checked the left channel . I have a signal (from the sig gen) making is as far as the input of the recording amp , (pin 9) but its not making it out again (pin 2) . Can you maybe confirm this would indicate a fault on the record amplifier please ?

David



P.s. Thanks Tony
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Old 11th Nov 2018, 7:17 pm   #6
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Default Re: Revox B77 No record left side

See my previous answer.
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Old 11th Nov 2018, 7:18 pm   #7
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Default Re: Revox B77 No record left side

Quote:
Originally Posted by TonyDuell View Post
Probably 'L-REC' is Low (amplitude) RECording signal and 'H-REC' is High (amplitude) RECording signal.
Sorry Tony, I said L when I meant Y. I've now corrected it.
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Old 11th Nov 2018, 8:36 pm   #8
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Default Re: Revox B77 No record left side

So far I've got it down to being between Q2 and Q3 somewhere.
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Old 11th Nov 2018, 9:23 pm   #9
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Default Re: Revox B77 No record left side

Joint break at the solder pad of C10 ...nailed it
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