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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 17th Jun 2016, 2:22 pm   #61
sennsai
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Default Re: Revox A77

Quote:
Originally Posted by vidjoman View Post
The picture shows the multiplug in place and I assumed it was that which was stopping the cover being removed.
No, I actually used a picture off the net.

2 Further points:

1. The capstan shaft finish appears to be a satin (bead blasted) finish, does this pic of it look normal?

2. When cold, and particularly with a full 10.5" in play on RH take-up reel, it tends to stall and spill tape. Ok when warm with empty RH reel.

I checked (by hand) the "free-ness of the motors with brakes disabled, the LH spins free and silent, the RH has a noticeably more drag with audible noise, so points to faulty bearings. Could this be the source of the tape spillage?
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Old 17th Jun 2016, 2:55 pm   #62
SteveCG
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Default Re: Revox A77

Sennsai,

Have you checked the physical state of the Rifa (clear yellow plastic) 0.47uF capacitors on the motor board ? Any cracks in their plastic cases?
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Old 17th Jun 2016, 8:11 pm   #63
Ted Kendall
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Default Re: Revox A77

The finish of the capstan looks quite OK - this was brought in with the Mk3 revision, if memory serves. The stiffness in the motor which clears on warming up certainly sounds like a bearing problem - first thing to check, anyway.
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Old 17th Jun 2016, 8:44 pm   #64
sennsai
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Default Re: Revox A77

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Originally Posted by SteveCG View Post
Any cracks in their plastic cases?
Had a close look, can't see any cracks. I've re-set the 24v rail slightly and lubed all board connectors. It's behaving ok just now but that might be because the motors are warm, so I'll test when cold tomorrow.

Quote:
Originally Posted by Ted Kendall View Post
The finish of the capstan looks quite OK - this was brought in with the Mk3 revision, if memory serves.
I've just looked it up, seems to be a Mk 4 (G207696)
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Old 17th Jun 2016, 9:05 pm   #65
Ted Kendall
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Default Re: Revox A77

Those Rifas are best replaced anyway. It's not a question of whether they fail, but when, and then the pong and general corruption has to be seen to be believed.
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Old 18th Jun 2016, 4:12 am   #66
TIMTAPE
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Default Re: Revox A77

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Originally Posted by Radio Wrangler View Post
15ips bodge number 1 is to muck about with the frequency discriminator so that the frequency locked loop runs the motor faster. If you're in a 60Hz country, this may still leave you a bit of margin. But you're running your motor bearings at double speed. If you're in a 50Hz country, the speed of field pattern rotation is slower, and you don't have enough margin, so this trick is said to be 60Hz only. Normal revoxes don't care about 50/60Hz
I understand now thanks. That's a bodge I'd not heard of or seen in jobs that came to me, probably because Australia is 50hz mains supply. I definitely wouldnt try it myself, 60Hz or no. I have occasionally come across bodge #2 though.

Tim
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Old 18th Jun 2016, 1:04 pm   #67
sennsai
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Default Re: Revox A77

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Those Rifas are best replaced anyway.
Ok, that's on the cards, and probably new motor bearings which fortunately are a standard size.
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Old 18th Jun 2016, 3:09 pm   #68
sykospain
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Default Re: Revox A77

Yes Andy, but why would you wish to keep using a Revox analogue tapecorder ? When the merest PC World laptop loaded with Adobe Audition will give you 16-bit definition audio that outclasses any 15ips stereo audio you ever recorded ? After 38 years in BBC Network Radio, I couldn't even give away my two A77s to the local Scout Hut radio station - they already had StationPlaylist radio playout software tasting from a 10,000 song database...

When I twenty years ago demo'ed the original Protools digital audio editing application on the Apple platform, which is now universal in radio & TV broadcasting, to a hoary old pre-retirement BBC tape cubicle engineer, and showed him how you could delete a section of recorded audio with one keystroke, then restore it instantly with a second keystroke, he literally burst into tears.. "All those years slashing at my fingertips with a razorblade..." he whined.
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Old 18th Jun 2016, 4:14 pm   #69
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Default Re: Revox A77

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Originally Posted by sykospain View Post
but why would you wish to keep using a Revox analogue tapecorder ? When the merest PC World laptop loaded with Adobe Audition will give you 16-bit definition audio that outclasses any 15ips stereo audio you ever recorded ?
The early Americans came up with the phrase "Life, liberty and the pursuit of happiness" which seems as good as any other reason I've ever come across.

I've had an A77 for several decades and I fancy getting it going again just for fun. I'm typing at a perfectly good Apple, with quite a collection of lossless files on it., but I want to explore some of my old tapes again. In a few day's time I will be whizzing around the countryside surrounding a town in the Scottish Borders on horseback along with several hundred other riders, despite there not being anything wrong with the range rover I'll use to get there.

I've got an amateur radio transceiver running by my elbow, but nothing heard on it is out of range of my cellphone.

Sometimes it's nice to do things you once did, just for fun. HAVING to do it is a completely different matter, of course.

David
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Old 18th Jun 2016, 6:51 pm   #70
m0cemdave
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Default Re: Revox A77

Sykospain:

There's a big difference between using something for work, and indulging in a technical hobby.

When I need to edit a memory stick's worth of conference presentations for a podcast, I wouldn't dream of doing it on on anything but a computer. That's work.

But I still have the A77 that I bought new in 1974, keep it maintained in good condition, and enjoy listening to some of the tapes I recorded 30 years ago. Just a bit of harmless fun...
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Old 20th Jun 2016, 5:09 pm   #71
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Fair enough gents ! !
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