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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 13th Nov 2016, 1:39 pm   #1
jblink1
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Default Revox B77 History

Hello to everyone, post #1!

I have recently acquired a B77 Mk1 and would be interested to know its history, at least manufacture date. I contacted ReVox with the serial number but have had no response. I just wondered if the lack of response was normal or it there is an alternative source of such information?

On an unrelated topic I would just like to give positive feedback regarding NagraVox. I am sure many have seen them on eBay. My B77 is fully working but I intend to upgrade / re-cap as a winter project. I met with Peter from Nagravox as he happened to be in London (he lives in Australia) and he spent a couple of hours looking over the B77 free of charge and with no obligation to purchase anything. Very knowledgeable and gave me the confidence to attempt the work. I feel sure those with Studer / Revox / Nagra gear will be familiar with Peter, but I wanted to just add my comments
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Old 13th Nov 2016, 2:50 pm   #2
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Default Re: B77 History

There is a ton of stuff on the net about these not the least of which is here http://www.reeltoreel.de/worldwide/B77.htm

As its got a load of integrated circuits inside most likely some will have date codes which will give you a fair indication of manufacturing date.

Good luck and welcome to the forum.

Cheers

Mike T
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Old 13th Nov 2016, 4:03 pm   #3
Restoration73
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Default Re: B77 History

Revox B-series introduced in 1979. I bought a new B77HS sync in 1981 for £660. The
normal version was £630.
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Old 14th Nov 2016, 3:19 pm   #4
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Default Re: Revox B77 History

Hi and welcome aboard.
This may sound like a silly question, but if it's fully working why do you need to 'upgrade and re-cap'? Personally I'd be inclined to leave well enough alone expecially if you're not that experienced.
AFAIK the only caps that give trouble in Revoxes are the Rifa type which are usually across the mains. These are used in many machines of the 60s and 70s, Tandberg is another example, and can burn up. See the threads on here.

Revox kit is well made and parts are usually 'findable'. There were so many B77s made you should have few problems finding spares or donor machines. I have a B215 cassette and I have only had to change the pinch rollers. They're practically maintenance-free.
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Old 14th Nov 2016, 10:13 pm   #5
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Default Re: Revox B77 History

The attached Revox B77 review/test report reprint dates from 1978 March.

(Not the best of scans, but I have the original somewhere and can rescan if needs be.)


Cheers,
Attached Files
File Type: pdf Revox B77 Review HFP 197803.pdf (910.6 KB, 354 views)
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Old 15th Nov 2016, 7:51 am   #6
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Default Re: Revox B77 History

I do tend to agree with Ben. Those kits also include the preset potentiometers, if you change or disturb them you will need to recalibrate the whole machine (or certainlythat part that you've disturbed/replaced) for that you need special test equipment to set it up accuately.
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Old 15th Nov 2016, 2:23 pm   #7
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Default Re: Revox B77 History

Love the proper technical review, those were the days!

Younger readers will be baffled by the lack of references to 'microdynamics', 'PRAT' etc.
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Old 15th Nov 2016, 9:31 pm   #8
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Default Re: Revox B77 History

Quote:
Originally Posted by ben View Post
This may sound like a silly question, but if it's fully working why do you need to 'upgrade and re-cap'? Personally I'd be inclined to leave well enough alone expecially if you're not that experienced.
Hi Ben

Not a silly question and I get your point. I have most of the parts and am intending to change initially ones that are going to cause problems (the 0.1uF decoupling capacitor for example across the transformer that apparently (and evidently from the burns on the wiring) can go up in smoke.

Beyond that perhaps it is just a balance between enjoying and learning. I am a chartered mechanical engineer with perhaps a wish I had gone down the electronic route all those years ago. It is a personal challenge I am presently enjoying, if somewhat nervously

I changed the right hand tape guide for a roller bearing because as a "mechanical" I did not believe that polishing the fixed one was really the main purpose of the tape. As it stands owning the B77 is a lifelong (well since 1979 when they came out) ambition I have finally achieved. I may end up doing the "wrong" things and I really value the opinions of people who know far more than me and can keep me on a sensible track.

Cheers

JB
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Old 15th Nov 2016, 9:38 pm   #9
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Default Re: Revox B77 History

Quote:
Originally Posted by Michael Maurice View Post
I do tend to agree with Ben. Those kits also include the preset potentiometers, if you change or disturb them you will need to recalibrate the whole machine (or certainlythat part that you've disturbed/replaced) for that you need special test equipment to set it up accuately.
Indeed and that is an area in which I intend to proceed with caution. please see my reply to Ben. To replace open pots with sealed ones is a clear improvement, but I wholly agree there is a risk regarding calibration. That is why I am reticent about jumping in feet first, but at the same time it will be a great learning experience. I am not averse to obtaining equipment ( I have a digital 'scope and DVM, but I know that is not enough) and much is available at reasonable prices. I am not after a studio quality calibration, just something a 50+ something bloke with bad hearing can appreciate
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Old 16th Nov 2016, 2:51 am   #10
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Default Re: Revox B77 History

Quote:
Originally Posted by jblink1 View Post
I changed the right hand tape guide for a roller bearing because as a "mechanical" I did not believe that polishing the fixed one was really the main purpose of the tape.
I believe it's advisable to retain the standard RH tape guide ring because it's designed to act as a damper for the pull of the take up reel.

I also agree with Ben that apart from the few known faulty caps, changing all the caps can be a waste of time and effort unless there is a definite problem such as a lack of bass response. On my B77's and A77 I've changed the known faulty caps and the rest are original.

Things like pinch roller and capstan shaft, heads and head alignment can be far more critical to performance. I'd be looking at those first.

All the best with it,

Tim
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Old 16th Nov 2016, 10:19 am   #11
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Default Re: Revox B77 History

Cheers! The pinch roller IS non standard s,o although it appears to be functioning OK, will be replaced. Heads about 50% worn and alignment... well I can only go by the guy who sold it to me and his checklist of checks.

I get the damper comment and you may well be right. On the other hand the dampening will only really have an effect starting and stopping and at constant speed all it is providing is drag.

Incidentally the main motor caps are showing signs of leakage......
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Old 16th Nov 2016, 11:46 pm   #12
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Default Re: Revox B77 History

It seems to have become fashionable to completely recap equipment like this. In some cases they may need replacing but it also depends on the quality of the part you are replacing it with.

It seemed to have started when the poor quality chinese capacitors started popping their tops in the early 2000's.

There are good capacitors and there is utter rubbish. I only use Panasonic or Vishay capacitors which I get from RS or Farnell.

Some of the presets suffered from their wipers breaking up, but if you replace them you have to re-calibrate the machine.

Replace the mains filter cap, the RIFA on the speed control board and the motor run if they are showing signs of age, the rest, I'd leave until they fail.

If you decide to do the whole machine, then do one board at a time and test it after you've done it and before you work on the next module. That way any faults can be easily diagnosed.
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Old 17th Nov 2016, 10:15 am   #13
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Default Re: Revox B77 History

Quote:
Originally Posted by Michael Maurice View Post
Replace the mains filter cap, the RIFA on the speed control board and the motor run if they are showing signs of age, the rest, I'd leave until they fail.

If you decide to do the whole machine, then do one board at a time and test it after you've done it and before you work on the next module. That way any faults can be easily diagnosed.
Speed control cap done as is the mains filter. Sound advice regarding one board at a time. I did see a post on another forum where a guy had done them all in one go and....you can guess the rest.

As mentioned this is partly to "upgrade" and partly for experience / pleasure so I may well end up changing components for the hell of it rather than sound technical reasons. I do intend to act with extreme caution as I understand fried B77's are not a good thing

As always the opinions of those who know more than me are welcomed.

Cheers

JB
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Old 17th Nov 2016, 2:48 pm   #14
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Default Re: Revox B77 History

Be careful of the board connectors too. I feel sure that you may eventually chose to upgrade to the PR99, and in this machine one of the two tape path rollers is used to measure the duration of the tape's passage. Head access is also better.
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