Revox F36 main motor not spinning

[ChinTong]

My F36 main(play) motor stop spinning. All other functions work well. Appreciate help.

[DMcMahon]

So just to be clear, capstan motor is not working so no drive in Play mode, but Fast wind in both directions is working OK from the reel motors ?

David

[ChinTong]

Yes. It’s correct. Was working the day before. Motor spins smoothly when rotate by hand. Appears power supply problem.

[DMcMahon]

Same problem in both tape speeds ?

[ChinTong]

Yes

Also noted the rewind motor behave strangely. At times, it spins on play mode, and the spinning can be stopped by fingers. Rewinding is perfect. Just service the brakes!

[barrymagrec]

Could be the motor cap.

[ChinTong]

Thanks

Is this capacitor suitable?

[barrymagrec]

Probably, if 2uf is the correct value, but it`s easy enough to check for volts on the motor before making random component changes.

[Michael Maurice]

A voltage check may not give much information, unless you get near zero volts, because the capacitor is there to shift the phase of the mains by 90 degrees.

The supply motor will spin in play with low torque as that’s how back tension is effected.

[DMcMahon]

Originally Posted by ChinTong

Thanks

Is this capacitor suitable?

Often not the Motor Run capacitor but only way to be 100% sure would be to change it.

2uF is correct according to schematic (double check the stated value of old part), this MRA PRO440 series seems to be suitable for Motor Run applications, not sure why the double contacts.

David

[ChinTong]

Thanks for the inputs. I changed all the 3 capacitors. When I switch to play mode on first try, it turns😄. But on subsequent tries, it’s dead!

Anyone know the value of the resistor on a small fiber board attached to the solenoid

[Michael Maurice]

The motor should run as soon as the machine is switched on.

You've replaced the motor run capacitor, the only other thing is the speed change switch. unless the motor itself is faulty.

[ChinTong]

Thank you Michael, check and service the speed switch, now the 71/2 speed works but not the 3 3/4!

[ChinTong]

Found another problem, the rewind motor runs on play mode! Causing tape not running

[Ted Kendall]

Originally Posted by ChinTong

Found another problem, the rewind motor runs on play mode! Causing tape not running

It should do, but at reduced power, to provide back tension. Is your pinch roller OK? If it's hard it won't grip well, and bear in mind that capstan wear is not uncommon on these machines.

[ChinTong]

Originally Posted by Ted Kendall

It should do, but at reduced power, to provide back tension. Is your pinch roller OK? If it's hard it won't grip well, and bear in mind that capstan wear is not uncommon on these machines.

Adjusted the brake tension and the machine works on 7 1/2 speed only. Still failed to get 3 3/4 speed to work. The sound quality is good considering the age of this machine. Has to replace the pinch roller.

[Michael Maurice]

There are 3 positions on the tape speed selector 7½, OFF 3¾ check that the 3¾ button is frully pushed down, otherwise check for broken wires and faulty switch tags.

[ChinTong]

Originally Posted by Michael Maurice

There are 3 positions on the tape speed selector 7½, OFF 3¾ check that the 3¾ button is frully pushed down, otherwise check for broken wires and faulty switch tags.

Thank you Michael, will certainly follow your advice and update

[ChinTong]

It works but stop working again after a few reels. Now the pinch roller solenoid not working. The tape end detection and brake solenoids are working fine. Appreciate help. Thank you in advance

[Ted Kendall]

The shunting diodes across the solenoids and on the switchpack can give trouble with intermittent operation.