A look into the Revox A77 and its restoration

The Revox A77 was well ahead of its time when it got onto the market. Even today an interesting peace of equipment that is fun to you and that sounds pretty good.
In this episode I am providing an idea around restoration process withe the help of the documentation that came with an excellent restoration kit from Nagravox.

[@clauscombat418]

Thanks for this exellent video. The best starting point video on the subject here on YT 👍

[@pcallas66]

I have an A77 and from the looks of your pictures it is a MK IV. I had to do a couple things mechanically to it but it works great and is a 2 track version with 3.75 and 7.5 ips. Good sound is effortless on it. Thank you for sharing.

[@ThankyouCity]

Cool video mate. I have been using an A77 lately to record either stems from my mix or wholes tracks too. It's really fun and interesting exploring the saturation you get. It would be great if you were to upload another informative video of the operation process, general usage, upkeep of the machine and anything else. Id be really keen to see that. Great video on this one!

[@RetroPanic]

Good work and video , thx! Here in in Switzerland where is the original birthplace of these reel to reel tapemachines. I do revisions. I usually replace the potentiometers with new closed ones.

[@conundrum112]

Excellent video from a fellow Revox lover.

[@linuxholgi]

Thanks Harvey, appreciated!

[@conundrum112]

No worries.

[@michaeldavison9761]

That component list for the 1.077.725 capstan speed control board at 8'41" in the video is the only place I've seen a possibility of P201 being 2.5K. The schematics I have seen all say 1k so when it fell to bits recently, 1k is what I ordered only to find it fitted with a 2.5k pot' when I removed it. It looked as if the old pot' had been set around 1k so I cut one of the PCB tracks and bridged the gap with a 470ohm resistor which does give a finer control of the 800Hz signal from the tacho head at 3.75ips.

[@AleMarasso]

excellent video, I subscribed to your channel !! Thank you very much for all that information !! I'm about to buy a revox a77, where can I get the link to download the manual you used for repairs? Thanks!!

[@joebruhin2098]

Hi, mine has been in storage for a long time....the right wheel head seems to be frozen...thoughts!

[@modgrip805]

Hi. Great video, thanks. Could you link to this upgrade/refurb product? Many thanks! Edit: Found them! Thanks.

[@S8San]

The tape recorder does not play from the tape. You can see the selector on the input, not NAB or IEC, the inputs on AUX. On the A77, normally during playback, the vumeters do not work, only with an artifice... so

[@fickfehler3866]

Can a 2 track A77 properly erase a previously recorded 4 track tape from a Technics RS1506 ?

[@oscarbit]

Hi mate, could you tell me where can I get this restoration kit please? I've a Mark IV and it needs to be restored, TKY

[@par4n1]

Do you sell upgraded boards to the consumer?

[@MrMoromette]

How could one get the service doc.of 117 pages, do you have a link or reference to help us and our Revox machines? Thank you !

[@lu4enp]

Marian Vlad i’d like to see it too

[@dkmmhdk]

If a electrolytic capacitor shows a higher value than it should be could be a sign that the capacitor is leaky. It is in deed fascinating to look at a reel to reel machine with the large reels. Is yours a 2-track or a 4 track deck?

[@ClassicHiFiReviews]

Thanks Mikael! I did not know that about the capacitors, thats a good information. This one is a 2-track. I should have mentioned that in the video :-)

[@dkmmhdk]

@@ClassicHiFiReviews I was also a bit puzzled the first times i encountered this behaviour. But it actually makes sense that the leakage passes some of the measuring-signal passed the capacitor an in doing so fools the meter to show a higher capacity.

[@conundrum112]

Do you have a link to the full service manual please.

[@brunohebert1351]

check hifiengine.com

[@mpmp7609]

@ClassicHiFiReviews Hi and thanks for tour vid’ guy… Do you think it’s possible to bring me the .pdf that you talk about please to see what the probably problem of mine ? I think it could helo me a lot…. Great thank ❤

[@Neutrinfo]

I found last year a Revox on the sidewalk thrown away as garbage, it should be possible to restore it.

[@ClassicHiFiReviews]

Of course. ReVox are pretty modular and the ReVox decks are extremely expensive. You might have found something in the garbage that's worth broken $1k.

[@ikomlino]

Hi. I just get mk4, 4 track. Is there possibility to convert it to 2 track?

[@ClassicHiFiReviews]

To turn it into a 2 track you would need new heads. On top of that some electrical changes of course. The service manual of the 2 track version will have all information you need.

[@albertgibson1667]

I own two A77s, a half-track running 15 ips and a quarter track running 7 1/2 ips. These things were like buying cars, lots of options. Your basic A77 came quarter track with 3 3/4 ips & 7 1/2 ips. You could specify quarter track or half track, with any two adjacent speeds, 1 7/8 ips to 15 ips. For extra money you could get full track, continuously variable speed, built in power amps and speakers, Dolby noise reduction or a stainless steel veneered front. Inside, as you know, it's built like a brick shithouse, and the service manual is a masterpiece. At one time I used a Lamb Laboratories 4-channel mixer the same size, shape and appearance as an A77. I use digital mixers, now, and a DAW. Digital has it all over analog by any measurement parameter you can name. But NOTHING sounds like analog, and I'll never part with my A77s!

[@ClassicHiFiReviews]

Thanks Albert, great comment and sounds like you got some interesting stories to tell!

[@miss.wright3035]

At 10:43, the after image shows 2 caps daisy chained side by side to replace the original horizontal capacitor. That is not good practice, the physics of 2 side by side is entirely different vs the original integrated cap. Very surprised a proper cap replacement wasn't provided.

[@yuyuyuyu2175]

Hello sir my name is ko nay lin live in myanmar I this like reel to reel tape recorder revox

[@andreybrodianski5596]

Two capacitors in series increasing ESR by 2. It is stupid cheap solution to save money on good axial capacitor. Never try to save money restoring such equipment - use high quality components (I don’t mean audiophile gold foil caps, just reliable classic brands) Also old caps sometimes show better measurement results than modern, so I solder them back ;) Also these kits generally much more expensive, in compare to just buying this list of components, so you can buy better components for same money. Bottom line be careful with all these restoration kit money makers.

[@dubdoodle7191]

Suckers pay thousands for a Nakamichi Dragon cass deck, yet an A77 reproduces superior sound and far less $$$. !/4" tape is for serious tape enthusiasts, cassette's for radio recording warriors LoL