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REVOX B77 Mk 2

SaSi said:
It could well be a matter of adjustment. On the PR99 there are two trimmers that control when these LEDs light up. "Unfortunatelly" my B77 came in pristine condition and I never had a chance or reason to check calibration or the circuits.

I suspect it should have similar controls though. Do you have a service manual? I just had a look in that and in section 6.4.6 it states that the overload indicators are "calibrated" by the values of R37 & R34 in the monitor amplifier (1.177.260). In newer versions (I suspect MkII) these resistors are replaced by trimpots R30 & R38.

These trimpots, if available, should be accesible from the bottom of the machine, however, unlike the PR99 where they are readily available through the bottom, in the case of the B77 you need to remove the unit from it's housing and lay it on it's back. Then you have access to the trimmers at the bottom.
Click to expand...

Thanks again, man! I got the LEDs to fire by reversing the leads, but they fire unevenly, so I will try the adjustment... after I get the service manual. Would cold solder joints affect them? That is definitely the case here.
Also, when fast winding I hear a loud buzz, probably from the supply-side guide roller. What would be the right lube to use on that, and the pinch roller shaft?
 
You won't achieve much if the supply guide roller starts to make sounds. It's really cheap to replace it. it's a standard SKF part. Get 4 for $2 to last a lifetime.

The pinch roller shaft needs only cleaning with alcohol. Unscrew the pinch roller philips screw, remove the cover, roller and shims and clean everything but the roller with alcohol, including the inner shaft of the roller wheel. Then put things back together.

How did you "manage" to have the LEDs in reverse polarity? Didn't you replace the whole VU assembly? IIRC the whole thing connects together in a socket.
 
SaSi said:
...How did you "manage" to have the LEDs in reverse polarity? Didn't you replace the whole VU assembly? IIRC the whole thing connects together in a socket.
Click to expand...

These meters were used freebies that had been snipped out so I had to solder them in. The LEDs had cut wire pieces still soldered on but the insulation colors did not match my machine's wiring.

Many thanks to you and persil!:thmbsp::thmbsp::thmbsp:
 
the b77 mkII is indeed a good machine.

Before getting a b77 up and running please replace the following parts:
-counter belt
-counter ring
-pinch roller
-first tape roller

Cleaning:
-clean the tape heads with some isopropanol and also the tape leaders
-demagnetise the heads

Immediate succes garanteed!
 
This is a good checklist for servicing the machine. I would also add a check on the breaks performance. Sometimes the metal film liners need cleaning with alcohol and often the break linings on the break wheels need replacement. I have been luckier with replacing the whole wheels than stick a replacement pad on the existing wheels.
 
stevevdb said:
the b77 mkII is indeed a good machine.

Before getting a b77 up and running please replace the following parts:
-counter belt
-counter ring
-pinch roller
-first tape roller

Cleaning:
-clean the tape heads with some isopropanol and also the tape leaders
-demagnetise the heads

Immediate succes garanteed!
Click to expand...

The only things a haven't done is replacing supply-side roller, and demagnetizing. Tell ya what, though... I made a great sounding tape with it last night.
I have a Teac demag unit, but no instructions. Definitely gotta replace that roller... it makes a loud buzz when rewinding.
 
You might want to get 2 of these rollers and experiment replacing the RHS stationary aluminum riction roller with a bearing.

The stationary roller supposedly reduces W&F but I have seen better and smoother packing of tape with a roller there. And we have the PR99 with the same motors and transport (high speed though) that has a rotating roller there (tape motion sensor and tape counter feed).

And you might want to inspect the tension guide to the left: It might have a groove from years of use. If it does, then the edges cause wear to the edges of the tape. Apart from replacing it, you can also turn it by 90 degrees or so. Use pliers and some thick carton to catch the steel rod so that you don't scratch it.
 
SaSi said:
This is a good checklist for servicing the machine. I would also add a check on the breaks performance. Sometimes the metal film liners need cleaning with alcohol and often the break linings on the break wheels need replacement. I have been luckier with replacing the whole wheels than stick a replacement pad on the existing wheels.
Click to expand...


Replacing the whole set is an option that I also prefer. I got mine from revox germany for 100 euros (about 120 US dollars i think). Brand new original revox drums.

My main b77 2 track had some replacements and revisioning:
-two new bearings in the motors
-new capstan motor
-revising of the set of plug in cards (all 5 of them)
-new pinch roller
-new first roller (the tape roller on the left)
-new powersupply
-revisioning of the tape speed board
-revisioning of the tape mechanism
-revisioning of the interconnect board
-revisioning of the tape transport control board
-brand new heads: butterfly head!
-and of course the alignment of the machine: hours of work
 
and here is the photo:

DSC04935.JPG
 
KentTeffeteller said:
Hi,

The ReVox B77 Mk II was made until 1986! This was the best machine ReVox made of the A and B 77 line. Parts are available from J-M Technical Arts and these decks are service/maintenance friendly. Worth owning if you like open reel!
Click to expand...

small correction: the b77 mkII was made untill 1992.
 
SaSi said:
You might want to get 2 of these rollers and experiment replacing the RHS stationary aluminum riction roller with a bearing.

The stationary roller supposedly reduces W&F but I have seen better and smoother packing of tape with a roller there. And we have the PR99 with the same motors and transport (high speed though) that has a rotating roller there (tape motion sensor and tape counter feed).

And you might want to inspect the tension guide to the left: It might have a groove from years of use. If it does, then the edges cause wear to the edges of the tape. Apart from replacing it, you can also turn it by 90 degrees or so. Use pliers and some thick carton to catch the steel rod so that you don't scratch it.
Click to expand...

I turned the take-up-side tape guide around about 90 degrees so the tape will be contacting a smooth round surface (instead of a worn surface) and I've recently noticed something. The tape pancake does not wind in the exact middle of the take-up reel... it is definitely closer to the front "wheel" of the take-up reel. I had the whole guide apart at one time and there is a thin brass washer that goes on first, and that thing is a bitch to get into proper position so that the bolt goes through it. I laid the deck on its back so that it would not slide around but I can't tell if I got the bolt to go through the washer or not. I may have the washer caught in a bind between the bolt and the nut. The tape is not scraping against the reel but it is not well centered in the middle.
I'm not even sure what my question is here... unless it's "is this proof that I need to redo the assembly of the tape guide and get the washer installed correctly?" If I don't what is the best method for getting it right?
 
If you are refering to the brass tape guides in the headblock, these should not be altered. Their function is to guide the tape through the heads.

Regarding tape packing and metal reels, I've seen all sorts of bad things and not just in Revox decks. The Teac X-1000 has an adjustment that moves the reel plates back or forward so that the tape packs in the middle of the reel and doesn't scratch the surface. I've adjusted that for one reel and found that another was scraping the edge.

Frankly, I've given up on metal reels. I have found that the plastic 10.5" Revox reels are the best. The don't bend, they are lighter and FF/REW and also braking is smoother, tape packs much better on them and - the most important - they are perfectly centered. Centering a NAB reel with an adapter is another piece of black magic I have yet to master.
 
There's a pretty good deal out "there" on some Maxell 35-90B UD-XL blank tapes. The ad says "high bias" ...I don't think so, but in any event, does anybody know how these sound on the B77?
 
Glad to hear the B77 is working OK! I have never had much luck with those tapes on my machine, Emtec, BASF and Quantigy 456 seem the best (and the ReVox tapes are best match!). Also found the way the tape winds on the spool can be effected by the NAB adaptors you are using, obviously the ReVox NABs are best, and for me the Akai ones are the worse.
 
It's great when recording. I thought about it myself, and will eventually get one. No use if you play back mostly.
 
Yes, I've been thinking about it everytime I see one when I search for cheap parts on German ebay.

Same here, as I can use other decks for recording, there is no real need.

I just wonder why Revox designed the pause button to - not - work. As if there were no R2R and cassette decks before the B77 and they improvised.
 
SaSi said:
Yes, I've been thinking about it everytime I see one when I search for cheap parts on German ebay.

Same here, as I can use other decks for recording, there is no real need.

I just wonder why Revox designed the pause button to - not - work. As if there were no R2R and cassette decks before the B77 and they improvised.
Click to expand...

Mine only has an effect if I hold it in. Other logic-controlled decks I've seen had a pause button that you push and it stays in while paused. Push it again to un-pause and it pops back out. I guess this "pause memory" lets you push once to pause and push again to un-pause. The change is easily reversed so my question is moot (about keeping it all original).
 
Same on mine and same on the PR99 MkII and III.

Only problem with that PCB is that I find it too expensive for just a flip-flop and two sockets.

OTOH, I've seen a nice digital tape counter that fits perfectly in the B77 tape counter slot for (IIRC) $80.
 
I need to clean up the case on my B77 so I can close it up and it has tobacco tar stuck to it. Does anyone know of a strong cleaner that will not harm the painted textured finish of the case?
 
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