Revox Motor Problem

carlosraj

New member
Hi

I am having this problem with my Revox. When I start play, at the beginning, there is no problem and it plays as normal. After about 40 mins, there is a slight drag. The take up motor gets very hot and there is no torque. If I place my finger on the motor, just lightly it slows down and it seem like it has no push. After a while, I realise there is some smell from the transformer and it starts to get very hot. At this point I switch off the player, to prevent from further damage. I tried switching the motors from left to right and vice versa, but still no difference. If I turn off the player for about 30mins and restart,it plays as normal. What could be the problem. I checked the 4 triacs and they seem to be OK. Please assist.

Thanks

Carlos
 
Which Revox model are we talking about?

Does it still have the original Rifa capacitors and have you checked the motor run capacitors? Have you checked the voltage on the motor?
 
Which Revox model are we talking about?

Does it still have the original Rifa capacitors and have you checked the motor run capacitors? Have you checked the voltage on the motor?

This is a B77 and I think it is a MK11, it has a connector behind for capstan speed control. All the aluminium caps have been changed except the tantalium. I am not sure which are the motor run caps, you mean the 3.5uf and 4.5uf non polarised caps.

Thanks
 
All the aluminium caps have been changed except the tantalium.

The Rifa capacitors are the slightly yellow/silver colour box shape capacitors. I think they're mostly 0.47uF (though I've yet to replace them on my own B77 as they're harder to get to than the ones on the A77). If the machine is left unused for any length of time they have a habit of cracking and letting moisture in and will start smoking when the machine is next switched on. These are the first capacitors to replace on a Revox. They need to be replaced by capacitors of the correct type - I'd suggest using X2 rated capacitors.
 
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