Pardon my ignorance but did you say that the 710 has a clock? Mine doesnt seem to tell time at all.
Hi, the answer to your question is in the user manual available there: https://www.reeltoreel.nl/studer/Public/Products/Revox/Revox_B710/Revox_B710_MkII_Op_LR.pdf, see page 27 of the PDF file.
Yep. The motors I used are tight no side play like the originals had. The deck does exactly the same thing as it was doing with the slack motors. It seems to start spinning slower at about 70% both on rewind and FF. The motors seem to spool pretty strong when I hold them. I cant understand why they slow down at 70%. Makes no sense because the tapes are easy to wind with a pencil. Maybe its the back spin supply. My power is good and new caps keep the source stable. I'm going to try to switch over the wires on the motors from each motor so that FF will rewind and rewind will FF. If it doesn't blow up, I should be seeing the problem happen in the other motor. If that's the case then I might have a marginally bad motor or it might need to be taken apart and cleaned. Thanks for the help. I will let you know how it goes. I have a lot of revox gear and I never could understand why such high end gear like revox has such cheap cct boards and horrible caps in everything they made. I have some cheap brands that never had these problems.
No its the dreaded mk1
I know that it has a sort of timer but a clock that tells the time I didnt know that. I looked at my manual last night and I did see the info about the timer but the English version seems to have translation inconsistencies. I played around with the clock part but when I shut it off I lost the hours. In fact, when I unplugged it, I lost all time
I confirm that there is no battery backup, which is fully understandable given that the B710 and Studer A710 were never intended to be alarm clocks - which is also why they do not display the time when they are off. Programmed recording/playing is not their strong point, but if you look at the history of their inception they were designed to be high quality recorders/players with studio operation in mind, and were the best that the technology of the late '70s could offer in this domain. Real-time clocks, OTOH, did not come for free at that time, and consumer-oriented functions such as programmed recording were clearly not part of the basic requirements, it came as an afterthought.
Sorry, I know that this is a very popular internet myth, but as an engineer I have to lecture you in 1980-ish electronics, and sorry if I sound harsh, this is not my intention. These parts were not cheap or horrible at all. On the contrary Revox used some of the best parts available at their time, including the tantalum caps that "internet experts" despise today. These capacitors were actually 5 times more expensive than their chemical equivalents, and were chosen because they were better (that is, than the chemicals of their time), and they were perfectly suitable at the places where their were used (ie. never reverse-polarised). The engineers who designed these machines were definitely neither bozos nor cheapskates, but they had no way to know (a) that some people would still use their products 40+ years later, and (b) how long components would last. Seriously, Studer used mostly the same parts for their broadcast and studio equipment (the main exception is the trimpots, which were usually industrial types instead of Ruwidos), and it's not just Studer. For example I've just restored a bunch of Schlumberger recorders that were made roughly in the same era, designed without compromise for trouble-free 24/7/365 operation in nationwide radios, and I for one was not at all shocked to have to change many electrolytic capacitors and ball bearings (let alone the pinch rollers and heads), clean most switches and pots, and recalibrate everything. The Nagras are (usually) less trouble after all these years but, in order to achieve that, they were made with aerospace-grade components and cost the price of a decent car. This is just normal aging, if you cannot accept it then vintage equipment is probably not for you.
There is more to a power supply than a cap. I have seen power supplies that had the correct voltage when unloaded, but collapsed once they had to provide current, due to a faulty rectifier for instance. You do need to measure (with the proper instruments), assuming is not enough
Not quite sure if you are talking about R80 and R81, the trimmers that adjust the TACHO-L and TACHO-R sensitivities, but if so they are duplicated as R4 and R5 in one of the versions of the MkI head lifting circuit (section 6/15, page 52 of the service manual I linked to in a previous post). It should be fairly easy to add the trimmers if you have the version of the head lifting circuit without them. There are a few other differences between MkI and MkII but these are essentially small changes in resistor values, I don't think they can account for Fl's problems.
I confirm that there is no battery backup, which is fully understandable given that the B710 and Studer A710 were never intended to be alarm clocks - which is also why they do not display the time when they are off. Programmed recording/playing is not their strong point, but if you look at the history of their inception they were designed to be high quality recorders/players with studio operation in mind, and were the best that the technology of the late '70s could offer in this domain. Real-time clocks, OTOH, did not come for free at that time, and consumer-oriented functions such as programmed recording were clearly not part of the basic requirements, it came as an afterthought.
In fact you need to know that, just to keep the real-time clock running while the B710 is "off", the latter is not really turned off. It is just in a different mode in which the capstan motors are not running and the display just shows a dot, but the CPU board is still fully powered (the clock is actually derived from the CPU's clock by a piece of software) so the deck still draws non-negligible power when turned off. This is not sloppy design by Studer, just how things were done with the technology available at that time, but that means that you are probably better off powering it from a switched socket than trying to display the clock all the time. That clock is not terribly accurate anyway, since it comes from an ordinary 4MHz crystal instead of a watchmaking-grade oscillator. One cannot expect 40-odd years old equipment to have all the refinements of 2022 equipment.
Sorry, I know that this is a very popular internet myth, but as an engineer I have to lecture you in 1980-ish electronics, and sorry if I sound harsh, this is not my intention. These parts were not cheap or horrible at all. On the contrary Revox used some of the best parts available at their time, including the tantalum caps that "internet experts" despise today. These capacitors were actually 5 times more expensive than their chemical equivalents, and were chosen because they were better (that is, than the chemicals of their time), and they were perfectly suitable at the places where their were used (ie. never reverse-polarised). The engineers who designed these machines were definitely neither bozos nor cheapskates, but they had no way to know (a) that some people would still use their products 40+ years later, and (b) how long components would last. Seriously, Studer used mostly the same parts for their broadcast and studio equipment (the main exception is the trimpots, which were usually industrial types instead of Ruwidos), and it's not just Studer. For example I've just restored a bunch of Schlumberger recorders that were made roughly in the same era, designed without compromise for trouble-free 24/7/365 operation in nationwide radios, and I for one was not at all shocked to have to change many electrolytic capacitors and ball bearings (let alone the pinch rollers and heads), clean most switches and pots, and recalibrate everything. The Nagras are (usually) less trouble after all these years but, in order to achieve that, they were made with aerospace-grade components and cost the price of a decent car. This is just normal aging, if you cannot accept it then vintage equipment is probably not for you.
Getting back to your problem: after reading your posts, I am not sure if you did more than change the electrolytic and tantalum caps and the spooling motors. If not, then you did not really restore your B710 so problems are definitely possible. You really need to change the trimpots as well (much more troublesome than the caps: I had to change almost them all, on all the Revoxes I've had in my hands, as the wipers have gotten brittle and break by just looking at them), plus the usual cleaning and lubrication of the transport with PDP65, and then follow the service manual to check and calibrate everything. It wil take time, skills and equipment, and I wish there was a cheap way to make a 40-years old deck (any deck, not just a Revox) work as it should. Unfortunately, experience and training have taught me otherwise. The good news is that, if you cannot do it yourself, there are a number of professionals out there who can do it for you, including Revox service centres (yes, they still exist!). The other good news is that, once properly restored, your B710 is a great deck, well worth the effort.
There is more to a power supply than a cap. I have seen power supplies that had the correct voltage when unloaded, but collapsed once they had to provide current, due to a faulty rectifier for instance. You do need to measure (with the proper instruments), assuming is not enough
Interesting info and appreciated. Thanks. Ive repaired a lot of 215s but only a few 710s. Never worked on a mk2. This one although fairly clean needs a lot of work to get it running right but I'm down to only 1 spooling motor being bad. Im going to see if I can rebuild the motors myself but its more than likely that I will replace them. Jack from TN sells the ball bearing type and he's helped me a lot over the years so I will be buying a set from him. I figured out the clock. Not that it really mattered to me but I like all parts of my gear to be working so not having been too informed I got the info from a member where to look in the manual and it was easy to get going. Not having a spring tension gage made it tough to set up the new pinch rollers that ate a bunch of tapes. I finally have the tape flat and straight between both pinch rollers so its riding the heads nicely now.
Yep. I have that info of the a710 mods. I put in the 1n4001 diodes as it suggested and it does work but not enough. Jack gave a a tip about the spooling motors so I will try that first and if it works then my deck will only need some trim pots and maybe new rectifiers but only as a precaution. They work still under load but I've heard they can cause a lot of problems if the diode junctions short out.
Im gonna have a look and see the trim pots and if I can replace the resistors and adjust the back tension of the one spooling motor then I might be able to compensate for the wear. The diode mod did help somewhat but not enough.
