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Revox B77 Reel-to-Reel

Discussion in 'd.i.y.' started by ToTo Man, Jul 19, 2020.

  1. ToTo Man

    ToTo Man the band not the dog

    My uncle has gifted me his Revox B77 reel-to-reel. It's the 7.5ips/15ips 2-track version. Needless to say I'm chuffed! :) He demoed to me working but says it hasn't been used in some time so will likely need a service.

    I'm not entirely new to the B77. I bought a partly-restored one on eBay a few years ago but ended up returning it for a refund as it had a few minor issues that concerned me and I didn't want to go down the rabbit hole of spending more money on it. Things are different this time, my uncle has owned this B77 from new so I know its history and that it hasn't been hammered over the years, therefore I don't mind spending a bit of money on it if necessary to restore it to perfect working order.

    I have a million questions to ask, but let's start with a few basic ones:
    - Is there anything I should inspect before powering it up and using it? It's been a while since I researched the B77 but I have vague recollections of it containing 'Rifa' capacitors that have a tendency to smoke and/or explode. Should I be worried about this?
    - The surface of the unit looks very dirty with ingrained dust. My dad wants to take a wet cloth to it but I'm concerned this will simply make things sticky and ingrain the dust even further. What is the best way to clean the unit?
    - Lastly, and without getting ahead of myself, is there anyone within a reasonable distance of Glasgow (e.g. 75 mile radius) of Glasgow who could be trusted/recommended to restore a B77?

    PS - When responding with advice, please assume my technical knowledge of the mechanics and electronics of R-2-Rs is nil :).

    Cheers.
     
    Last edited: Jul 19, 2020
    ummagumma and allthingsanalog like this.
  2. Tony L

    Tony L Administrator

    I’ll let others comment on the electrical side, but as for the casing I’d budget on getting it re-done. There are places that can re-do the Nextel finish, I’ve seen the service advertised on eBay. You’ll never clean it to an acceptable degree.
     
    allthingsanalog and ToTo Man like this.
  3. ToTo Man

    ToTo Man the band not the dog

    My dad has tentatively started to wipe it down with a wet sponge. Results look promising. Will post before and after photos shortly.
     
  4. Zombie

    Zombie pfm Member

    ToTo Man likes this.
  5. 337alant

    337alant Negatively Biased

    The B77 is a fantastic Tape deck and well worth the effort if the Heads are still in good condition.

    There is one Rifa X2 cap attached to the inside of mains input, replace it with a similar X2 cap with 275VAC rating 0.1nf
    I did a thread on resoration of a Revox B77
    https://pinkfishmedia.net/forum/threads/revox-b77-restoration.227008/
    I stated this in that thread

    Like all Revox R2Rs they are 30+ years old so capacitors in particular need to be changed
    The Revox used all good quality caps Frako & Phillips electrolytics and tantalum caps
    The tants and Frakos have a habit of failing short so are best replaced with a modern day equivalent
    Alan
     
    ToTo Man likes this.
  6. ToTo Man

    ToTo Man the band not the dog

    That's a superb diary, Alan. I wish you were closer to Glasgow so I could enlist your services (I'm assuming you're in the south?). My dad *might* be able to replace one or two caps (I say might as he's never replaced caps in mains-powered electrical items, only in loudspeakers, and that was torturous for him, - he's not a natural with a soldering iron!), but if it needs a full overhaul then I best have someone else do it.
     
    Last edited: Jul 19, 2020
  7. 337alant

    337alant Negatively Biased

    I live in Hartlepool Co Durham
    Be careful with the de-soldering and re-soldering some boards can lift tracks with too much heat

    Alan
     
  8. essgee

    essgee pfm Member

    Glasgow to Hartlepool is not that far and you would get an expert doing the work.
     
    ToTo Man likes this.
  9. ToTo Man

    ToTo Man the band not the dog

    I now have the case off the machine. Is this the Rifa capacitor (see image below)? Is it likely other components on the machine may have been damaged by operating it with the cap in this state? Anything else I should inspect visually?

    [​IMG]
     
    allthingsanalog likes this.
  10. 337alant

    337alant Negatively Biased

    Yes thats it, If it failed open circuit then no problem
    IF it failed short then the fuse would fail so check the mains fuse on the back panel and the 2 fuses in the power supply
    If you dont have a replacement for the Rifa right now just snip through the cap leads as it will work without it for now
    Also check for bulging or leaky capacitors on all boards, check if there are any signs of heat burning or scorch marks
    Looks like a lot of dust in there as well which is worth vacuuming out, I use a paint brush and an open ended vacuum pipe
    Alan
     
    ToTo Man likes this.
  11. ToTo Man

    ToTo Man the band not the dog

    I've just inspected the heads and the play head looks like it's grooved, though it could just be ingrained oxide. I'll post a pic after I've cleaned them. Are new heads still available?
     
  12. Tony L

    Tony L Administrator

    Heads are LOLprice! You can never tell much until you have really cleaned them. The heads on my humble 4000DB were barely visible due to all the sticky brown crud, but cleaned up virtually as new after a lot of work gently cleaning them. It takes way more than a simple wipe with a cotton bud soaked in isopropyl if they are seriously caked, it can be more like an archeological dig!

    PS Obviously 15ips gets through them far faster!
     
  13. ToTo Man

    ToTo Man the band not the dog

    How do you suggest I clean them? Isopropyl-soaked cotton t-shirt rag wrapped around index finger?
     
  14. Tony L

    Tony L Administrator

    Just expect to take a lot of time if they are really caked. I think I spent about half an hour at least on the Akai, just going very slowly and gently with the cotton buds, a duster and 99% isopropyl as I really didn’t want to do anything that might scratch them. They came up good:

    [​IMG]

    If your machine came from a family member and home-use (which is unusual for a 15ips deck) I’d not expect it to be hugely worn. Hopefully you’ll be pleasantly surprised after a good deep clean. I wish I’d taken a ‘before’ picture of the Akai as they really were caked to the point I couldn’t really even assess them before bidding. I only left a £30 bid and was delighted by how well I was able to clean it up after winning. It really does look beautiful now, no scratches or chips anywhere, and beautifully clean and shiny.

    Arguably worth getting a head demagnetiser too, they are pretty cheap (I think I paid £15 for a new one) and I’m sure this machine sounded better after being done. I also changed the belts and pinch-roller (it had been left in ‘play’ at some point so had a dent), but beyond that just cleaning and a bit if re-lubing inside as some of the grease was sticky. It seems to work fine. I’ve not recapped it.
     
  15. ToTo Man

    ToTo Man the band not the dog

    I suspect this B77 might have been used more than I anticipated. I figured the heads would be in the same condition as those on the TEAC A-3440 he gifted me in the mid-2000s (i.e. some minor flattening), however it makes sense that his 2-track machine would have seen more use than his 4-track as the latter was used only for multi-tracking. All the A3440 needed was a head/guides clean, new pinch roller and belt. I haven't used it for a few years though so it'll no doubt need another new belt! It's getting to that age where it could probably do with a complete recap too! I'll keep working on the B77's heads and see how they clean up.

    PS - I have a Teac E-3 demagnetiser but have never used it, - too scared I'll balls it up and render the heads unusable!
     
  16. Tony L

    Tony L Administrator

    Its really simple. Mine has a rubber cover so you can’t actually bang it into the heads by accident. Obviously do it with the tape machine turned off. Turn the demagnetiser on, move it slowly towards the heads, move it around a bit fairly slowly whilst not touching the heads (when you are close you can feel it vibrating very slightly), and then slowly back away to a distance of two-foot or so and turn it off. It is apparently worth doing the metal parts such as tape-guides too. Its easiest to do with the machine on its back. Far easier to do open reel decks than cassette decks as obviously the heads are more accessible. After some thought I did the tape guides first and then each head in turn. I was working on the assumption it hadn’t been done for 45 years or so, I’d likely not be that thorough normally.

    PS There are lots here who know far more about tape machines than I do so happy to retract any of the above if Alan, Charlie or anyone says I’m wrong. I googled it and watched a couple of YouTube videos, that being how I acquire knowledge these days!
     
    ToTo Man likes this.
  17. 337alant

    337alant Negatively Biased

    Take a close up shot of the heads for me and I will tell you how worn they are. There are wear guide and every Revox head, which is the slot at the top and bottom.
    If the wear flat spot equals the wear flat spot on the heads they are 100% worn
    The strange thing is they sometimes perform perfectly good even with 90%+ wear so all is not lost
    To clean the tape heads and guide properly try 99% isopropanol, if that doesent work use Acetone this will work with a little effort and some q-tips
    Just dont use it on your pinch roller and dont get on plastic
    I recommend "platen clean" for the pinch roller rubber and for the Pinch & Capstan roller sintered bronze bearings only use PD-65 oil
    Alan
     
    ToTo Man likes this.
  18. 337alant

    337alant Negatively Biased

    Tony
    You are not wrong in your approach to demagnetisation and if the demag probe is coated with rubber then its OK to get very close to the heads and guides, in fact its very difficult to not be pulled in by the strong magnetic field and touch the heads but its OK if its coated as they dont actually touch metal to metal.

    I use a Han-D-Mag which is very powerful for the open reel machines and I start with the machine switched off and on its back and in a separate room to any tapes or anything sensitive to a strong magnetic field, that includes all your credit cards mobile and smart watches.
    I plug my demag into a short un-switched extension lead that I know has 100% good connections. If the de-magnetizer loses power whilst close to the head I can leave it permanently magnetised.
    I switch on 2 meters away and slowly approach the left hand end tape guide and erase head making a slow up and down movement then side to side movement then slowly move away.
    Then move back in on the record head then slowly out and in again on the capstan shaft and guides, then slowly out then in again on the Play back head and out slowly to 2m away then switch off
    Alan
     
    ToTo Man likes this.
  19. ToTo Man

    ToTo Man the band not the dog

    Thanks Alan, will do. When I got the A3440 a chap on the AK forum kindly mailed me a small bottle of Caig's Rubber Rejuvenator which was difficult/expensive to source in the UK at the time, is that the same kind of formulation as platen clean? It worked wonders on the A3440 roller and I also used it on my cassette decks too. I'm sure I still have the bottle somewhere. Whether it'll still be usable after 15 years is another matter! :D

    I might have a look on youtube to see if there's any videos on oiling the bearings as this is something I never got round to doing on my A3440 as I wasn't really sure how to do it. Is PD-65 ok for the A3440 too? Does the oil that's already in the bearings need to be cleaned out before new oil applied? You can tell I haven't really got a clue when it comes to these sorts of things!
     
  20. ToTo Man

    ToTo Man the band not the dog

    I googled PD-65 oil but didn't find anything. Does it go by another name?
     

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