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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 14th Aug 2019, 9:58 am   #1
drewwagar
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Default Newly acquired Revox B77 Mk2 - Recording Issue

Hi Folks,

Opening post here, so apologies if commit any newbie gaffs.

I've recently been given a large collection of Revox audio gear:

- B77 Reel to reel
- B710 Mk2 Cassette Deck
- B291 Turntable
- B760 Tuner
- B750 Mk2 Amplifier

I've been lurking around here for a while, picking up tips and taking a slow and gentle approach to restoring these machines. Thus far I've given them a gentle external and internal clean.

On inspection, none of the troublesome Rifa capacitors have been replaced, so that job is on the list. However I have done a basic operational check on the machines.

The amp is currently DOA, to be investigated. Tuner and Turnable are fully operational. Cassette deck is operational but pinch rollers are in poor condition, otherwise working fine.

The most interesting, to me, is the B77. I have already replaced the tyre for the pinch roller. Playback is working fine, along with FF/RW. However, the B77 is unable to record.

Recording controls appear to be working (both indicators come on when the switches are flipped) but nothing appears on the VU meters when an audio source is provided and the monitor switch set to 'Input' (I know the source is good as the B710 records from it fine).

Unfortunately I can't test the erase function as the only tape I have is a recording I don't want to erase! I have a blank tape as well. I am hopeful the erase/record aspect is working, but the lack of input means there's nothing to record.

I'd appreciate suggestions on how to proceed with diagnosing the input/monitor side of the machine.

Many thanks,

Drew.
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Old 14th Aug 2019, 10:16 am   #2
Michael Maurice
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Default Re: Newly acquired Revox B77 Mk2 - Recording Issue

Hi Welcome to the forum.

I take it that you are providing the source via the phono sockets at the back and that the inputs are set to AUX.

If that is correct, then you may have a fault on either the input card or the record amp card.

The record switches themselves dont have any influence on the input signal save that when the switches are down the inputs are reversed.

The switches themselves may need cleaning, that's not uncommon though unusual for both channels to be suffering.

What test equipment do you have?

You will need a scope and preferably an oscillator, that way you can trace the signal through the machine.

The service manual is available online.
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Old 14th Aug 2019, 10:23 am   #3
drewwagar
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Default Re: Newly acquired Revox B77 Mk2 - Recording Issue

Thanks Michael, much appreciated.

Yes - Source is via the phono sockets on the rear and the selector is set to Aux. I've also tried microphones in the front sockets with the selector adjusted accordingly - still no input shows on the VU meters regardless of the position of the gain dials.

I have access to an oscilloscope and can follow instructions, so I will go find the service manual online - that's a bonus!

I'll identify the two cards in the first instance and ensure they're seated correctly and there is no obvious damage.

I'd like to establish whether the equipment is worth spending time and energy on in terms of repairs/cost before I go too much further. Your website looks intriguing - I may be giving you a call when funds allow!

Cheers,

Drew.

Last edited by drewwagar; 14th Aug 2019 at 10:36 am.
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Old 14th Aug 2019, 10:42 am   #4
Michael Maurice
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Default Re: Newly acquired Revox B77 Mk2 - Recording Issue

The machine is definitely worth repairing and bringing up to spec. They are excellent machines.

Pinch Rollers for the B710 are available here
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