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Revox B 795

bikezappa said:
Robie

I have lost track of your Revox table issues. Have you fixed it?

Are you going to install an IR sensor and control your table with the Revox remote?

Peter
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I just received some very inexpensive Hall sensors and I'll be checking with markthefixer regarding his availability to assist.

The B795 has no remote and as I understand it, the Hall sensors detect the rotation of the magnets on the bottom of the platter and adjust voltage to the motor accordingly. Evidently, one (or both) of my sensors is bad and the originals are no longer available. Substituting new sensors will be an interesting experiment.
 
Robie said:
The B795 has no remote and as I understand it,
Click to expand...
Not standard out of the factory. The optional IR receiver is/was the B202, and any of the handsets B201, B205, B208 will operate it.


The B790 has a different motor from the B795, B791, B291, H9 which all used the same motor. The operational principle is the same, but the physical assembly is different. I have not opened a B790 motor yet, so no hints, sorry.
 
Hi-

I can help with the B790 motor. You need to remove the 3 screws on the motor's bottom casing and then remove this bearing assembly housing. THEN, you need an "expanding" c-clip wrench to remove the rotor's c-clip which will allow access to the small pcb (printed circuit board) that has the external wires connected to it. Usually the stress on the motor's wiring harness has caused a wire on this small motor pcb to tear loose.

I'm doing this from memory (2-3 years ago) and hope I haven't forgotten anything or left something out - hope this helps!

Dale
 
This is a follow up note on the idea of "Remote Controlling" the Revox TTs. The B791 came equipped with the "connector/wiring harness" to just add a B202 IR Receiver and then use a Revox B201, B201CD, B205 or B208 Remote Control to operate it (some of the early connector/harness assemblies were missing a resistor and capacitor though, so you need to be careful). The B795 TT required the purchasing of the "connector/wiring harness" assembly and its installation before you were good to go. The B790 is a WHOLE DIFFERENT STORY! The table needs to have the "connector/wiring harness" re-wired to fit a different connector on the Tonearm Control PCB AND the base of the table needs to be drilled for the 9 pin connector. The Tonearm Control PCB also needs to have a circuit modification to handle the signal from the installed B202 IR Receiver (assuming you've got this far!). How do I know this?? I've installed a remote control on my B790 and it was a bit of work to do the rewiring and trouble shoot the PCB mods before everything started to work correctly.

Oh, and one last thing. The original Revox "connector/wiring harness" is UNOBTAINIUM. You can get a modern one from a fellow on the Revox Forum in Germany (really great guy) at about $50 USD, but it's for the B791/B795 so it will still need to be modified for the B790.

Dale
 
Hi Dale

So the best Revox table for using the remote would be the B791 with the B202 IR reciever?

How do you like playing with the remote controlled B790 table?

Is it worth the pain of all the rewriting?

Peter
 
bikezappa said:
So the best Revox table for using the remote would be the B791 with the B202 IR reciever?
Click to expand...

Or a B291. The B291 is a B791 with inbuilt remote control.
The B291 has more remote functionality than a (B791+B202), such as remote pitch control, and remote speed & size selection.
 
Hi Peter -

I LOVE having the Revox TTs connected to a remote! I've got 2 B791s and 1 B790 (all with different cartridges) - all hooked up to their own B202 IR Receiver. The operation of all the tables is identical - the B790 when wired up correctly is no different in operation from the B791s.

People ask "why would anyone want a remote controlled turntable"? After I cue a record up, dim the room lights (if they were up when selecting a new LP), and get to my chair/sit/adjust it for my bad back, I've used about 30-45 seconds of time. Now I for one like to listen to an album from the beginning - NOT 30-45 seconds into Side 1 or 2. This is were the remote really earns it keep - you can get seated/relaxed and then start to listen, not trying to listen to the album's beginning while moving around the room and getting seated. I'm also lucky in having a dedicated listening room upstairs, but my wife love to yell upstairs "when are you coming down to dinner? Blah, Blah, Blah." With the remote I can instantly lift the tonearm, answer her back (not shouting over the music), and resume listening to the album side at exactly were I left off (I always convince her that "I just need to finish listening to this side").

I know I could do all this with a CD Player (and I do with a Revox B226 Signature customized with a "Double Crown" TDA1541A DAC), but I like vinyl better. If you've ever listened to an early "6 eye" Columbia copy of "Time Out" by Dave Brubeck, you'll know that there is NO better rendition of this classic masterpiece. I've heard the CDs and the reissues, they are poor, poor substitutes.

Dale
 
Update on my B795!

I replaced many Frako caps and Blue Philips caps and adjusted the damper on it. It now works superbly free of problems. Thanks for your assistance on reviving it. It's now connected to my main system and is used as my automatic mainstay for my better vinyl. It sounds superb and is the best automatic I ever owned. Total investment, $67. :tresbon:
 
boyerd001; If you've ever listened to an early "6 eye" Columbia copy of "Time Out" by Dave Brubeck said:
You got that right! Have the "6 eye" vinyl, and the cd reissuse. The only time that cd gets play is in the car, beyond that I could put a handle on it and use it to slice pizza.

What Cart are you running in that Revox? I'm running a Grado Z2+ in my 795.

Dave
Click to expand...
 
boyerd001 said:
I LOVE having the Revox TTs connected to a remote! I've got 2 B791s and 1 B790 (all with different cartridges) - all hooked up to their own B202 IR Receiver.
Click to expand...

I successfully interfaced my B795 to my B200 AV-Controller. Now I have ReVox's "Easyline" operation of the turntable too. That means the components all talk to each other. You don't have to press multiple buttons to get things going - just pressing 'phono' on the amp will power off anything else that happens to be on, and cue the record.If you select any other source, the stylus is lifted and the record is stopped automatically.
 
Hi Dave -

For cartridges on my Revox TTs, I've got: (1) B791 with an AT150MLX; (2) B791 with a MusicMaker III (Grado Gold w/nude FineLine stylus and additional internal dampening); B790 with an AT440MLa.

The B790 is awaiting an "upgrade", I just can't decide what "sound" would be that different from the 2 cartridges on the B791s. I have thought of really going wild and buying an AT33PTG moving coil for the B790 since that has a fairly high compliance and would match the 4 gram effective mass of the Linatrack arm. Even though made by AT, hopefully being a Moving Coil it would be different enough from the Moving Magnets to sound unique in its own right (at the moment I'm too poor after buying several Nick Drake albums!!).

Dale

Dale
 
boyerd001 said:
Hi-

I can help with the B790 motor. You need to remove the 3 screws on the motor's bottom casing and then remove this bearing assembly housing. THEN, you need an "expanding" c-clip wrench to remove the rotor's c-clip which will allow access to the small pcb (printed circuit board) that has the external wires connected to it. Usually the stress on the motor's wiring harness has caused a wire on this small motor pcb to tear loose.
Dale
Click to expand...

Thank you.

Is there a way to test the tachometer output from the B790 or B795 motor while it is disconnected from the rest of the machine i.e. by rotating the platter manually? I have a DMM and a frequency counter but no oscilloscope.

Regards,

Peter
 
Tachometer Output

Hi Peter -

Don't really know of any way to test the tach output without a scope (don't know the characteristics of your frequency counter in the DMM). You can check the continuity of the tach coil in the motor by "Ohming" the 2 Blue Wires going into pins 14 and 15 of socket J6 on the Motor PCB (this info from the B790 Service Manual).

Dale
 
I don't have the lead counter balance for my 795. What's the heaviest cart that can be set up with the brass counterbalance?

Dave
 
boyerd001 said:
The X2 EMI capacitor is behind the Power Transformer (which is labeled for 110vac) on the small PCB that has 6 wires going into it (power cord/power transformer/on-off switch). There are 2 Digikey numbers for this cap since the original RIFA has a 20mm lead spacing and nothing you will find will be that: 0.1uF (10mm lead spacing) Digikey #BC1601-ND; 0.15uF (15mm lead spacing) Digikey #BC1605-ND.
Click to expand...

A Kermet cap. with 20.3mm lead spacing is available from Mouser although it's out of stock at the moment. The manufacturers part no. is PME271M610MR30

See http://www2.mouser.com/ProductDetail/Kemet/PME271M610MR30/?qs=ffqAhwBssBt6RQ/tmIDf3g==

Peter
 
I've just 'upgraded' a B795 i.e. RFI suppression cap. x1, electrolytics x8, bridge rectifiers x2 and voltage regulators x3.

Are there any worries now about alignment/adjustment to either the Tone Arm PCB or the Motor PCB? I'm getting a bit paranoid as an album that played OK before now has tracking issues - but is it warped and not very clean!

I read this on the Revox Forum, http://www.revoxforum.de/forum/showthread.php?t=3426, but my problem may not be the same.

Regards,

Peter
 
Here is an update on my Revox B795 ( http://www.audiokarma.org/forums/showpost.php?p=3336698&postcount=116 ): the Motor Control PCB is in badly damaged, with many contacts destroyed. At this point the easiest route is to find a replacement board. I will send an e-mail to Studer to see if they have a spare one for sale. Another possibility would be to find a donor machine, and I'll be looking around in auction sites for one. The rest seems to be in good shape. I've replaced the electrolytic caps as adviced.
 
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