• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Revox B710 mk II stopping in playback, refusing to rewind

U

usernaim

New Member
Hi, I just got a single owner B710 mk II and I fired it up. First tape wouldn't play at all, though would rewind, although sometimes I had to jiggle the tape in the well to get it to go. Hmm. Took that over to my Nak DR2 and it wouldn't play or rewind at all. OK, bad tape.

Next tape (an XLII from the 90s) plays, but after a while it stops. Rewinds and ff on one side, but on the other no dice.

What do you think I'm looking at here? I can do basic repair but anything complicated and it goes to a repair shop, or ebay.
 
Register to hide this ad
The B710 mechanism has a tape protection system that prevents snapping by stopping the motors if the tape stops of slows down due to tension, so your problem may be caused by old cassettes getting stiff. Some other machines may still be able to play them, at the risk of snapping the tape. You might try to exercise the cassette by a fast forward / rewind cycle in such a deck if you have one, or (safer but cumbersome) by hand with a Bic pen, before you try again to play those tapes in your Revox. As a last resort, you might move the tape into another shell. Whe a cassette starts doing this, your first priority should be to make a backup if it is special. If not, it is probably best to just toss it.

But since this deck is new to you, it's probably best to first assume that it may be faulty, by playing a couple of known-good cassettes, i.e. a new cassette from a good manufacturer.
 
These decks are fickle. Even fully rebuilt. The sensing of the tape tension is TOO aggressive and the light barrier will often shine through thin or worn tape, causing stop.

The cassette inserted switches will likely need cleaning. They are leaf type switches with carbon contacts. Clean by running a strip of paper through each while holding closed.

Yes, you have to take the mechanism apart to do it.

No doubt the single owner deck is in mint condition and worth every cent paid. Except it's not. Even if it works, it will need servicing. Usually the motors need rebuilding and new capacitors.
But what do I know. I'm sure you will be the lucky exception.

BTW, the deck is EXTREMELY fickle with old pinch rollers. do yourself a favor and get a replacement set. You can thank me later.
 
A lot of good info here. Ive had the same problems with 710s and the 215s. I have one now that has noticeably a small wobble in the spooling motors that when I rewind or play the deck, it will randomly stop. I havent yet recapped it but I dud measure both spooling motors and voltages did not decrease as they got slower while spooling. I heard these motors are notorious for spooling motor bushing wear. Absolutely get the correct pinch rollers. There are the early small and larger one, then the later ones that are the same as the 215. Its a must. My deck has a lead in problem. After it rewinds to the beginning on the tape, its supposed to forward to the beginning of the tape automatically. It doesn't do that. Not sure where to begin with that issue. Anyone know what circuit I should be looking at for that tape lead in problem? Anyone know where I can get bushings for the spooling motors or even a tech trick that would get them working? Someone was talking in another forum about actual mini ball bearings they were able to find. So far, I've not found any parts support other than new pinch rollers from various sellers and cap kits but motors???? I saw used ones on ebay but the seller never responded. Probably worn oval also.
 
FI de HI said:
I've not found any parts support other than new pinch rollers from various sellers and cap kits but motors???? I saw used ones on ebay but the seller never responded. Probably worn oval also.
Click to expand...

I do rebuild the motors with precision ball bearings! Cheaper than a used motor.
 
Yes, a rebuild with ball bearings is the best solution. Revox in Villingen-Schwenningen (Germany) offer this also as repair. Order good quality bearings with 7mm outer diameter, 3mm inner diameter and also 3mm thick. Two for each motor. Be carefully with disassembling, this motors were not produced anymore. Especial carfully with the fine contact brushes. After all, the motors running very well and the drive runs longer out than with bronce bearings. The friction is lowered.
 
Tinman said:
I do rebuild the motors with precision ball bearings! Cheaper than a used motor.
Click to expand...
That would be awesome but I just finished replacing both motors with known good ones and still have the FF problem. Also the lead in on rewind is not working. Im wondering if there is not enough supply current for the spooling motors as they both seem to slow down some what at about 80% in either direction. FF being the main problem. I could send you these to rebuild with bearings and give that a try. If that fixes the problem I will send you 4 more to do. Not that they need it but it would be better to get them done now rather than later. What's the cost for a set?
 
I’ve had 4 sets done by Tinman for B215 & B710MKII. All were perfect. So good, in fact, that when I installed a set in one B710MKII, both reels continuously rotated with no tape and in the Stop position! I had to reduce the balance potentiometer to just below that threshold. I don’t think that same adjustment is on the MKI. Maybe Marc knows.
 
I don't discuss prices in open forums, that's what PM's are for. Also "known good" does not mean they don't "drag". That is usually the problem. The reset to zero after rewind is caused by the end of tape sensor OR it's intensity adjustment. Providing the motors are not struggling to move the tape.

Perry, I think there was an upgrade for the MKI. Mine has it. I do not have the details handy, but my deck has an add-on board soldered to it with a pot.
 
Yes, that is it. I also responded in the other B710 thread. It was not on all the MKIs, but it is in all the MKIIs. The back tension mods were only in later MKIIs, but it can be easily added.
 
You must log in or register to reply here.
Back
Top Bottom