Revox A77 Bearings - UK Vintage Radio Repair and Restoration Discussion Forum

Linnovice · 11th Dec 2017, 11:45 am

Hi all. I want to service an A77 and replace the left tape guide, reel motors and capstan motor bearings (not the sintred one on the capstan). In the service manual there are three different part numbers but as the machine is getting on for 50 years old I doubt Revox carry the spares. Can anyone recommend good replacements and a reliable supplier please. I want good quiet ones, not the cheap roller skate variety. Thanks in advance for any advice given. Mike

Boater Sam · 11th Dec 2017, 12:46 pm

If these are ball or roller bearings, chances are that they are standard sizes, metric or imperial. The big bearing suppliers such as Bearing Services should be able to match them. Try The SKF catalogue on line for ideas.

Ted Kendall · 11th Dec 2017, 4:17 pm

Nagravox are pretty good...

Linnovice · 11th Dec 2017, 6:30 pm

True, I’ve bought from Nagravox in the past. Carriage charges for some bearings would be exorbitant from Oz. There must be equivalents in the U.K. surely? I just what the differences are between the three separate part numbers.

vidjoman · 11th Dec 2017, 8:35 pm

Take the bearing out and it should have a type number etched onto it. I suggest the 3 numbers relate to different manufacturers.
I’ve use Wych bearings for various supplies. Very helpful, no interest except as a satisfied customer.

monaro0162 · 11th Dec 2017, 10:08 pm

I used an e-bay seller in Germany " saunabaubraunbraungmbh" to source new bearings. No vested interest - just a satisfied customer - the bearings were not that expensive with quick delivery. The bearings are marked with "ABEG ER 608Z" may help in sourcing equivalents. Incidentally I assume these are sealed for life? There does not seem to be any way to lubricate them.

Linnovice · 12th Dec 2017, 10:08 am

What did you use the ABEG bearings for? Spooling motors? Capstan or tape guide?

vidjoman · 12th Dec 2017, 10:15 am

You can get these from Radiospares - look for 608z bearing - Google it and they show @ £3.60 each.

monaro0162 · 12th Dec 2017, 1:13 pm

Quote:

Originally Posted by Linnovice

What did you use the ABEG bearings for? Spooling motors? Capstan or tape guide?

Spooling motors. I believe that the same bearing can be used in the Capstan motor.

The tape guide bearings, one of them needs replacing on one of the machines that I have. I'm not at home at the moment so I can't look - what size are they, does anybody have an equivalent part number?

mark_in_manc · 12th Dec 2017, 5:18 pm

Some bearing factors have an online service where you can enter into boxes on a website the ID, OD and thickness - and sometimes what the bearing is (taper roller, ball-race, thrust race etc) - and it will come back with suggested bearing numbers.

Here's a site picked at random where you can do this

https://simplybearings.co.uk/shop/ad...7&keywords3=15

If it were me, I would use one of these and then (if I was feeling fussy) pick one from a 'reputable' manufacturer (that is, one I have heard of) with the sealing details (open, metal seals, rubber seals etc) copied from the one I wanted to replace.

English bearings can be more tricky (not the case with your Studer I imagine), but even here US ebay can be your friend. Postage can be nuts, mind.

cheers
Mark

Humber888 · 12th Dec 2017, 5:34 pm

Another source for all the bearings may be Revox-online in Germany. The tape guide bearing is something like SKF 626-2Z and the reel motors SKF 608-ZZ. I've never definitively proved whether these need to be stainless steel or not.

Ted Kendall · 12th Dec 2017, 6:12 pm

The roller bearing should certainly be non-magnetic, therefore probably stainless steel.

mark_in_manc · 12th Dec 2017, 7:00 pm

Here's a handy page explaining what the bearing numbers mean

http://www.engineerstudent.co.uk/bea...explained.html

From the numbers quoted so far, looks like the ones used are not stainless.

Humber888 · 13th Dec 2017, 10:19 am

Ted, not wanting to deliberately magnetise my working A77, I tried putting my little magnetic grabber up against the tape guide bearing of a gash head block I have. It was very definitely attracted to the bearing. I think this is an original one since it is suffering from surface corrosion. So that may imply that the originals fitted by Revox were plain steel. I do realise this is not the most scientific of tests and could do with others checking any discarded bearings they have.

stevehertz · 14th Dec 2017, 1:02 pm

There are lots of bearing manufacturers, and some poor ones amongst them. Once I've got the type number (etched on the bearing, then google it for more info/clarification if necessary) I buy SKF brand from whoever is selling them.

Humber888 · 14th Dec 2017, 4:58 pm

I had a look at what tape guide bearing is fitted in my A77 MK3. It is an SKF 394928A which crosses to a FAG 626.2ZR.L82. I can't find much information on this specific part but assume a standard 626-2Z would be fine. Incidentally a W626-2Z would be the SKF part in stainless steel. This sort of implies that the original was not stainless. Certainly the stainless part is a lot more expensive. Maybe it was assumed that you just demagnetised the tape path regularly.

11th Dec 2017, 11:45 am	#1
Linnovice Hexode Join Date: Jun 2014 Location: Chelmsford, Essex, UK Posts: 386	Revox A77 Bearings Hi all. I want to service an A77 and replace the left tape guide, reel motors and capstan motor bearings (not the sintred one on the capstan). In the service manual there are three different part numbers but as the machine is getting on for 50 years old I doubt Revox carry the spares. Can anyone recommend good replacements and a reliable supplier please. I want good quiet ones, not the cheap roller skate variety. Thanks in advance for any advice given. Mike __________________ Small Scotch, New Aids and Happy Ears

11th Dec 2017, 12:46 pm	#2
Boater Sam Banned Join Date: Dec 2013 Location: Middlewich, Cheshire, UK. & Winter in the Philippines. Posts: 3,897	Re: Revox A77 Bearings If these are ball or roller bearings, chances are that they are standard sizes, metric or imperial. The big bearing suppliers such as Bearing Services should be able to match them. Try The SKF catalogue on line for ideas.

11th Dec 2017, 4:17 pm	#3
Ted Kendall Dekatron Join Date: Jul 2008 Location: Kington, Herefordshire, UK. Posts: 3,675	Re: Revox A77 Bearings Nagravox are pretty good...

11th Dec 2017, 6:30 pm	#4
Linnovice Hexode Join Date: Jun 2014 Location: Chelmsford, Essex, UK Posts: 386	Re: Revox A77 Bearings True, I’ve bought from Nagravox in the past. Carriage charges for some bearings would be exorbitant from Oz. There must be equivalents in the U.K. surely? I just what the differences are between the three separate part numbers. __________________ Small Scotch, New Aids and Happy Ears

11th Dec 2017, 8:35 pm	#5
vidjoman Dekatron Join Date: Jun 2013 Location: East Sussex, UK. Posts: 3,326	Re: Revox A77 Bearings Take the bearing out and it should have a type number etched onto it. I suggest the 3 numbers relate to different manufacturers. I’ve use Wych bearings for various supplies. Very helpful, no interest except as a satisfied customer.

11th Dec 2017, 10:08 pm	#6
monaro0162 Pentode Join Date: Sep 2016 Location: Stansted, Essex, UK. Posts: 186	Re: Revox A77 Bearings I used an e-bay seller in Germany " saunabaubraunbraungmbh" to source new bearings. No vested interest - just a satisfied customer - the bearings were not that expensive with quick delivery. The bearings are marked with "ABEG ER 608Z" may help in sourcing equivalents. Incidentally I assume these are sealed for life? There does not seem to be any way to lubricate them. Attached Thumbnails

12th Dec 2017, 10:08 am	#7
Linnovice Hexode Join Date: Jun 2014 Location: Chelmsford, Essex, UK Posts: 386	Re: Revox A77 Bearings What did you use the ABEG bearings for? Spooling motors? Capstan or tape guide? __________________ Small Scotch, New Aids and Happy Ears

12th Dec 2017, 10:15 am	#8
vidjoman Dekatron Join Date: Jun 2013 Location: East Sussex, UK. Posts: 3,326	Re: Revox A77 Bearings You can get these from Radiospares - look for 608z bearing - Google it and they show @ £3.60 each.

12th Dec 2017, 5:18 pm	#10
mark_in_manc Octode Join Date: Nov 2011 Location: Manchester, UK. Posts: 1,875	Re: Revox A77 Bearings Some bearing factors have an online service where you can enter into boxes on a website the ID, OD and thickness - and sometimes what the bearing is (taper roller, ball-race, thrust race etc) - and it will come back with suggested bearing numbers. Here's a site picked at random where you can do this https://simplybearings.co.uk/shop/ad...7&keywords3=15 If it were me, I would use one of these and then (if I was feeling fussy) pick one from a 'reputable' manufacturer (that is, one I have heard of) with the sealing details (open, metal seals, rubber seals etc) copied from the one I wanted to replace. English bearings can be more tricky (not the case with your Studer I imagine), but even here US ebay can be your friend. Postage can be nuts, mind. cheers Mark

12th Dec 2017, 5:34 pm	#11
Humber888 Heptode Join Date: Jul 2012 Location: Bromley, London, UK. Posts: 702	Re: Revox A77 Bearings Another source for all the bearings may be Revox-online in Germany. The tape guide bearing is something like SKF 626-2Z and the reel motors SKF 608-ZZ. I've never definitively proved whether these need to be stainless steel or not.

12th Dec 2017, 6:12 pm	#12
Ted Kendall Dekatron Join Date: Jul 2008 Location: Kington, Herefordshire, UK. Posts: 3,675	Re: Revox A77 Bearings The roller bearing should certainly be non-magnetic, therefore probably stainless steel.

12th Dec 2017, 7:00 pm	#13
mark_in_manc Octode Join Date: Nov 2011 Location: Manchester, UK. Posts: 1,875	Re: Revox A77 Bearings Here's a handy page explaining what the bearing numbers mean http://www.engineerstudent.co.uk/bea...explained.html From the numbers quoted so far, looks like the ones used are not stainless.

13th Dec 2017, 10:19 am	#14
Humber888 Heptode Join Date: Jul 2012 Location: Bromley, London, UK. Posts: 702	Re: Revox A77 Bearings Ted, not wanting to deliberately magnetise my working A77, I tried putting my little magnetic grabber up against the tape guide bearing of a gash head block I have. It was very definitely attracted to the bearing. I think this is an original one since it is suffering from surface corrosion. So that may imply that the originals fitted by Revox were plain steel. I do realise this is not the most scientific of tests and could do with others checking any discarded bearings they have.

14th Dec 2017, 1:02 pm	#15
stevehertz Dekatron Join Date: Sep 2011 Location: Rugeley, Staffordshire, UK. Posts: 8,833	Re: Revox A77 Bearings There are lots of bearing manufacturers, and some poor ones amongst them. Once I've got the type number (etched on the bearing, then google it for more info/clarification if necessary) I buy SKF brand from whoever is selling them. __________________ A digital radio is the latest thing, but a vintage wireless is forever..

14th Dec 2017, 4:58 pm	#16
Humber888 Heptode Join Date: Jul 2012 Location: Bromley, London, UK. Posts: 702	Re: Revox A77 Bearings I had a look at what tape guide bearing is fitted in my A77 MK3. It is an SKF 394928A which crosses to a FAG 626.2ZR.L82. I can't find much information on this specific part but assume a standard 626-2Z would be fine. Incidentally a W626-2Z would be the SKF part in stainless steel. This sort of implies that the original was not stainless. Certainly the stainless part is a lot more expensive. Maybe it was assumed that you just demagnetised the tape path regularly.