Revox B77

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RemcoV

Well-known member
Joined
Jun 6, 2004
Messages
56
Location
amsterdam
Hiya..
found a Revox B77 in the scrapyard with our local broadcaster..
but the capstan isn't running..

anybody might have a schematic layin' around of this baby?

Thanks!

Remco
 
I cant just remember the web address but I got all I needed for Revox A77 and B77 by Googling "A77 schematic " or B77 circuit". There is a Swiss website that has all the operating a service books. I will try to track it down.
The guy with the A77 should start by changing ALL the small electrolytics on the plug in boards.
Small parts like pinch rollers and lamps can be found on German e-bay.
Steve
 
Yeah baby!

thanks Samuel! when i've got some time i'll dive into this baby and see what's wrong!

Greetz
Remco
 
great! i've been looking for schems for the B77 for ages... i have two of these babys.

anyone got any tips on this problem:

both of them make a quiet squeeky/screechy noise once you get close to half way through a reel. they are fine for the first 3rd or so of the reel.

i just have to keep rewinding and re-using the first 3rd or so of my tapes...!

i guess it must be some kind of tension/tape pulling/grabbing kind of thing but i don't know much about the workings of these machines yet.

i clean the tape path regularily so i don't think it's that...

anyone got any ideas?

thanks!
 
[quote author="haima"]both of them make a quiet squeeky/screechy noise once you get close to half way through a reel. they are fine for the first 3rd or so of the reel.[/quote]
Are you sure it isn't the tapes? If the tapes are old (80's/early 90's) that could be it. I have the same problem, but it follows the tapes not the deck :grin:

Best regards,

Mikkel C. Simonsen
 
The drive oscillator for most B77s/A77s that I have seen is a 555 circuit, but he chip is marked as something else. Many of the A77s required a shorting plug in the "varispeed" socket for the capstan to run... can;t remember if the B77 was the same... I have one in the garage, but it's all wrapped up...

Keith
 
[quote author="SSLtech"]The drive oscillator for most B77s/A77s that I have seen is a 555 circuit, but he chip is marked as something else. Many of the A77s required a shorting plug in the "varispeed" socket for the capstan to run... can;t remember if the B77 was the same... I have one in the garage, but it's all wrapped up...

Keith[/quote]

Nope, the B77 doesn't need the shorting plug.
 
The screeching noise is almost certainly the tape grabbing on the erase head. Those Revox erase heads seem to be a little abrasive causing old tape to grab there first. Sometimes I try a piece of sellotape over the erase head if I'm only playing back, ultimately though if the tape is shedding or sticking then you'll need to "bake" it.

A poor mans method is to run a fan heater in a small area with the tape left there for a few hours.

basically just dry it out.

The serious method is thermostats/ovens etc, 120 degrees for about 4 -5 hrs. I have had great success with tapes I am trying to run just long enough to dub without the grabbing.

I have a B77 and an A77 and even a G36, also have some bits left from a a dismantled A77.

LarryK
 
See Eddie Ciletti's page on using a food dehydrator for a great way to dry tapes...

I have a bit of trouble with som old ReVoxes if they've been sitting for a long time in a damp enviromnent, check the hubs where the brake bands grab. ReVox did it the 'opposite way' to a lot of manufacturers, in that the brake band is just a sliver of spring steel, and the 'friction' material is stuck on the hub. If the adhesive breaks down, it can become gooey and leech through the fabric of the friction layer, gluing itself -either partly or completely- to the brake band.

A quick check for giooey white mess around the brake bands is all it tales to eliminate or confirm this particular issue...

Keith
 
Hi guy`s,

Maybe I pop up late here, but I have schematics for all Revox (and Studer) machines, so if you need a particular schematic section I will help you but unfortunately I have no time to do manual copy.

--Bo
 
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