Revox B77 Check and Restoration
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- เผยแพร่เมื่อ 22 พ.ค. 2021
- Here's another reel to reel tape machine that needs some love and care! In this video I go through a check and complete capacitor replacement of this great machine.
- วิทยาศาสตร์และเทคโนโลยี
I have the 15 IPS version of this unit (MK2), love it :)
Very happy to found this video, thanks for your knowledge and information about this beautiful tape machine, I'm a lucky owner also and the machine needs some love, you made it more relaxing for me to start the restoration.
Really interesting and informative video. I have a Revox B77 which I bought through Ebay a few years ago. It works quite well but I will definitely be re-capping it soon when I get some free time. Many thanks for sharing your cleaning and recalibrating procedures!
I had teac (X3mk2) , I had Tascam (34)..3 years later and some luck a ReVox B77 mk2 came to me! 😮
Thank you so much for this detailed video of the necessary work to be done to retore an old B77 to its original specs and glory. I just bought a defective B77 that actually needs all the work you described in your very useful video. I will send this video to my repairman so that he knows exactly what needs to be done, and not waste too much time trying to understand the schematics and all the specifics of this machine. I also have a sick Tandberg TCD-330 and a similarly sick TCD-440A that need a complete service. Will you do a similar video for this model in the near future? A BIG thank you from Montreal!
Never liked the looks of a77 but it starting to grow on me and now i like it.
The brand and the fact it’s good sounded and quality and parts are easy and cheap makes one of these is my next project 😋☺️
I guess you found the other 3 Rifa caps and replaced those too?
1 is behind the iec power connector, 2 others on a small pcb behind the reel speed switch….
I found out about these when the one at the power went up in a massive cloud of smoke :(
Bought one of these (MK II) in '81. Recently started using it again. Really informative video, thanks very much. Occasionally get a bit of wow so I think I might have to look at the speed control circuit one of these days
I don't have a B77, but I do have an A77 MKIII which has been in the family since 1972. I have noticed from your video that the under-side of the boards are much better than those from the A77 series.
I have one! I listen to it with my Audeze LCD-X headphones powered by a Schiit Asgard Amp. I can literally take my computer and from a 3.5mm-rca cable I can take any audio from my computer, (yes I know digital but hear me out)put it on some master ATR tape, and absolutely any audio becomes saturated, smooth, deeper with bass, and just more power. It's a phenomenal machine to say the absolute least and its just unbelievable in everything it does. Great vid it was fun to get some cleaning/maintenance ideas!! Much love from indiana usa.
Dave - what a great score, not seen inside one before and all I can say is...its NOT a Sony! :) Enjoyed the design and ease of serviceability. Also impressed with some of your test gear...now I'm on the lookout for the HP 3581C, it would look real nice setting next to my HP 3580A. Also need to get a plotter! Enjoyed the video. ~Jack, VEG
Thanks Jack! Well, you have the mighty 3580A that can do everything (and much more!) that my 3581C does. And you can plug a plotter too! On the back there should be x/y and “pen” banana jacks ;)
But if you can score a 3581C in decent condition, you won’t regret the purchase, especially when you take a peek inside :)
Take care
Dave
great video man
I have a b77 MK2 and I absolutely love it best tape deck ever. Mine was factory serviced and calibrated and I also found a new old stock brand new tape head which I had installed in calibrated It's a fantastic machine You're going to love it
New tape heads are close to $800 USD per. I have 11 Revox RTR's with each calibrated for a different tape. Crazy...I know !
@@dubdoodle7191 no not crazy at all I saw a video of a guy who drilled a hole someplace in the unit where he could reach the screw that adjusted the azimuth of the tape head so he could put a screwdriver in there and very easily turn and adjust it based on the tape he was working with. But I am depressed about is the fact that there are no new companies making reasonably priced real to reels there are a few companies making them but they want ridiculous sums like $20,000 which is absolutely ridiculous.
I also changed the two pin mains input to three pin and connected chassis to mains earth, also changed the mains protection rifa cap at the mains connector, if this cap fails the chassis can become mains live, also changed the three motor control capacitors, the three big aluminium caps behind the mains panel.
Nice job great 👍🏻
Great Video.
I got a mint condition unit.
It's Big and Beautiful looking but man, such a hassle to use.
You left one exploding capacitor right near the power plug in-line with the mains. I mention it because it just failed on mine.
nice machine - 😃
Thanks for your video/
hope you used audio grade capacitors in the signal path areas ;)
Thanks for this very detailed explanation of what everything does inside of this machine. Scored this model from a friend who didn't have time to fix it. Had to replace a capstan stem that snapped in half, now it's up and running. Now the issue is that my right input is the only channel that records and plays back at the proper volume, and conversely, the left has a strong signal in monitor while recording and then ends up very weak on the tape playback. After recording separate instruments to L + R simultaneously at equivalent volume (in Mic inputs), When I playback, both inputs seem to have been recorded on the right channel only, and just a tiny signal on the left. Very puzzling, and perhaps you might be able to suggest a solution. I suspect the root of this issue lies in the recording amplifier board at 15:25 based on your description of its function.
Hi, thanks for the comment!
Well it could also be as simple as recording gain issue and it can be adjusted by a trimmer. Does the faint sound from the left channel plays back distorted as well? In that case it can very well be a bad capacitor or bad contact (dry solder joint on a component perhaps? I had this happened before) on the recording amplifier board.
Very good information and most helpful. I have a B77 Mk.II and I'm the original owner of the machine. Are you aware of a good shop that may perform the work that you did in my area. The recorder seems to be working very well however I would like it to cleaned and checked since I've had it since the 80's. I live in Salt Lake City Utah USA and any suggestion would be appreciated.
Hi. This is the best video of the working parts of a Revox b77 that I've seen. I have one that looks exactly like the vintage you have but it will not go into record mode. The record lights do not come on and all switches are in the proper position. It plays back prerecorded tapes fine. The problem started after I replaced the caps on the 5 plug in boards. I've triple checked the obvious things like cap polarity and values. All solder joints are perfect. I'm at a loss. Any suggestions you may have would be much appreciated. Thanks.
Hi! That’s strange, from what I understand, before the cap replacement it was working.. I can’t see how a cap replacement done correctly has killed the machine haha!
That being said i’d start with the obvious things:
it could be just some bad connection between the boards. If you haven’t already tried, just unplug and reassemble everything (connectors and boards) and try again. From what I remember the boards can be inserted only in one way, but check that are positioned correctly.
Anyway, if that does not fix the problem, it could be bad switches on the front, so try to clean them and try again.
If that doesn’t fix it either, it could be the logic part.. you can try to see with a pre-recorded reel of tape if it erases the recording. If it does, it’s the record board that has some fault; if it doesn’t, it could be logic or oscillator board or a combination of problems (i’d start with checking power supply voltages, oscillator output, trace signal through the boards etc.)
Hope it helps :)
I am currently restoring B77 Mk I and found out that the wiring from main transformer was not very "user friendly", or better to say - "service friendly", so I modified it a bit.
Thank you for this video! I just purchased a B77. I was planning on bringing it in for service, but you make me feel like doing this myself. Any hints for good capacitor kits in Europe?
Hi! I think on ebay there’s someone in Germany that sells the full recap kit
Love your videos & greetings from UK. I have B77 MK2 7.5 &15ips high speed in need of a full recap service however one of my VU meter red peak record level lights stopped working but I'm finding it hard to locate replacement light, not back light but red peak kight😢
Hi! Thanks for the nice comment! I think the red peak light can be replaced just by a normal 3mm or 5mm (can’t remember right now exactly what dimension) red LED.
In any case, if you really want all original parts, on ebay or other sites you can get a full vu meter replacement (however, it’s obviously the most expensive way).
Hope it helps ;)
Cheers,
Dave
@@DaveElectronics thank you Dave for taking time to reply 👍
Hi Dave! Great video! And channel. I'm getting a B77 this week. How easy/expensive is to change its speed up to 15 ips? Many thanks! Keep it up!
Hi! Thanks for the nice comment! So, the high speed mod in my opinion is not easy and I do not recommend you to modify the recorder for 15ips, if it's a low speed version.
Regarding the mod, I think that you would have to change the capstain motor (and get the high speed version) and probably the control board for it. I think the high speed version of the capstain motor doesn't even run at the same voltage (probably higher), so you could get the transformer of the high speed version of the B77 or increase the voltage with a step up converter of some sort...
Then you'd have to change the EQ and BIAS boards (IF it's even possible to swap them with the high-speed-version ones...). High speed EQ and BIAS settings are much different from the low speed ones, perhaps it will run just fine, but it would sound quite bad IMO...
So, in theory it could be done, but in practice... well, if you really want the high speed, I suggest you get the high speed version of the B77. If the one you're getting is a low speed one, well, it won't disappoint you ;) It sounds amazing just the way it is! (check my video of a test recording with this machine vs the digital master: th-cam.com/video/xqWKB3PcDCs/w-d-xo.html )
Hope it helps :)
Cheers! Dave
@@DaveElectronics Hi Dave! Many thanks! I really appreciate you taking the time to explain me all this! And consequently making me save some money. You are right, it sounds too complex to do the mod. I found a 15 ips version and I bought it. There’re too many versions of these beautiful machines :). Yep, I saw your other video; it’s the best comparison I found in TH-cam. Great work and great sound! I want the reel to reel for finishing purposes and also to slow down tempos and pitched naturally, which I do a lot in my job. Keep it up Sir!
The tape guide on the left has that ball-bearing he was cleaning - take care not to get any cleaning fluid into the bearing! The right hand tape guide has a non-rotating bushing instead of a bearing. This is the same as the A77 later models except B77 gives you nice easy to use bolt heads on top!
I am restoring B77 MKI and also noticed that instead of the bearing the right hand tape guide had a non-rotating aluminum part. First I was thinking that the seller put it saving money on bearing, so I replaced it with bearing :D Should I put the aluminum part back? Does anyone knows what is the reason for this?
Hi! The right hand guide is a completely fixed post, it was designed like that.
I think the reason is to maintain a stable tension (and probably also speed) of the tape between the pinch roller and the take-up reel. My other r2r decks (Tascam and Teac) both have a spring loaded arm after the pinch roller to keep a stable tension. Many (if not all?) other decks share the same spring loaded arm to accomplish the same thing. So I guess… Revox tried to save some money there? :)
BTW, I imagine that replacing the fixed guide to a rotating one instead, will affect the wow and flutter as well… I don’t think it will never affect tape’s life span, so I prefer leaving it as it was designed. ;)
This is amazing video! Thanks a lot!
Quick question, what product are you using with the cotton-stick to clean the different metallic parts?
Thanks again!
Hi! Thanks for the nice comment :)
So, for the delicate metal parts (such as the heads) I use pure isopropyl alcohol. For all the rest I use diluted isopropyl alcohol (~40%), with a bit of mild detergent (non foaming). I guess there are some household products that you can buy, just search for mild detergent for plastic parts, it should be fine. Note: be sure to not use ethanol on plastic parts, only diluted isopropanol ;)
Hope it helps!
@@DaveElectronics thanks a lot for your reply! I was not able to properly understand from the audio. (English is not my mothertongue language )
I just got a b77 that my father bought in the late 70s I think. I tried tried do a first test but it doesn't even turn on. Any recommendation about where I could start from for getting to check that? Or should I proceed with the whole cleaning as you perform in the video first?
Thanks a lot for your reply!! I love you video and I would love to make work my father b77, I mix dub vinyls and I would love to use this reel to reel as echo device for my effects 😁😁❤
B77 is a very nice machine, I’m glad you’re planning to use it!
Cleaning for sure is a great start :)
If it doesn’t even turn on it could be a lot of things.. I would start by checking the fuse, then power supply (voltages out of transformer and then out of the regulator section). Be careful when working with mains voltages though, if you don’t have any electrical experience you should ask to someone for help or be really careful ;)
(Try reseating all the circuit boards and the connectors, usually if the machine is not being used for a long time, there might be some oxide on the contacts, reseating them should fix the “bad contact” problem)
@@DaveElectronics thanks a lot!!!! Super excited about getting into restoring this machine!
Hi
My b77 mkii
Has no sound out of right channel
Any ideas
I personally prefer restoring a B77 over an A77, but that's just me.
Hi I have just bought it same model and it’s not working can you repair for me please 🙏
Hi Dave. I have a A77 that I stuck a bunch of money into because a mouse started chewing up copper wire inside the machine. The tech was given new circuit boards that got damaged in shipping because he didnt wrap up the 5 green boards on the bottom of the machine. Now the tech gave up and I dont have good channel separation when I turn the left channel, right channel knob. any ideas. Can I ask what country your located in?
Hi! If something got damaged in shipping, really could be everything at this point. I don’t know if you have some experience in electronics, but I would start by probing the circuit and follow the signal (find where it gets lost or degraded).
I live in Italy :)
What grease/oil thing did you use for the ball bearing and rollers around 06:40 and forward?
Or maybe rather it's a polish of sorts?
Hi! For ball bearings I used sewing machine oil, just a tiny drop. To clean everything else (including brakes, pinch roller, heads, etc..) I used pure isopropyl alcohol
Hi Dave, do you happen to have a capacitor replacement list? Thanks
Hi! Unfortunately I can’t find the list anymore. I wrote down the list of all the capacitors from the schematic (service manual) and then double checked with the real boards if I had everything.
All good, thanks for your help.
Are you in Italy?
Sì ;)
Sir. I want to Purchase 4 track stereo Spool tape recorder, PL give me the source, How I can Purchase tape recorder, PL give me details ,I am from India,
Hi, so I got the recorder locally. You can search on ebay, sometimes you can get good deals or if you have a local used electronics market it could be even better. For the tapes i get those from RTM, but I don’t know if they ship to India.