Uher reel to reel comes to a stop

[mrmagnetophon]

Well i have a uher reel to reel special 24, when i put it in fast wind, rewind, play, the motor bogs down and stops. I recapped everything except the main motor capacitors, as they test fine.
The motor is very free, and runs fine when the recorder is turned on, but nothing when i try to operate it. All fuses are good.

-Chris

[Steve_P]

Clean it, change any belts and then try it.

Cheers,

Steve P.

[mrmagnetophon]

All Belts have been changed, i've got it open when checking this (the back cover)
The motor literally stops running.

-Chris

[Michael Maurice]

Is this a single motor or 3 motor machine?

I would check preferably by substitution the motor run capacitor (s)

[mrmagnetophon]

Single motor machine.
-Chris

[mrmagnetophon]

Same problem with new capacitor.

[ricard]

The machine is not set at the wrong voltage, i.e. 220V when running on a 110V mains?

[mrmagnetophon]

No it is set to 110V, as close to 120V as you can set it, also the lights are all operating at the correct brightness.

[Steve_P]

Are the volts to the motor OK? Does the motor do the same when run 'off load'. When it is working, how easy is it to stop with your fingers?

If you can take it apart, do this and give it a clean.

The Motor could be faulty.

Cheers,

Steve P.

[mrmagnetophon]

No the motor volts are not ok it turns out, when in PB mode its 20-24 volts ac, when in fast wind modes its .04

-Chris

[Steve_P]

What should the voltage be?

I'd trace it back and clean all the buttons and contacts on the way.

Cheers,

Steve P.

[mrmagnetophon]

I'll try cleaning it should be atleast 20-24 volts, if not i think somewhere in the range of 40, as the motor is stamped 42V for the capacitor rating.

-Chris

[ricard]

If the motor is stamped something like '2.2 µF 42 V' I would think it is the capacitance of the starting cap together with the rated supply voltage of the motor, not the voltage rating of the capacitor.

[mrmagnetophon]

well, whatever the case, in the PB mode the motor is receiving 20-24 volts. I can't figure out why it is changing in fast forward when its only a mechanical machine.

-Chris

[ricard]

It would not be impossible for the design of a recorder to include changing the motor voltage during fast wind to get additional torque, or, seen another way, to avoid the motor getting too hot during ordinary play.

Certain Beocords which have a single (synchronous) motor, have a dropper resistor which is in the circuit during play, but short-circuited in fast wind mode to get additional torque.

On the Grundig TK819 et al the motor voltage is increased during start-up at 7 1/2 ips to get the machine up to speed quickly - a centrifugal contact then switches the motor voltage down once the motor has accellerated.

There must be countless other examples.

If the voltage during wind is only .04 V it would indicate something wrong in the transformer or motor voltage switching circuit.

[DOFFERY]

Have you checked the motor itself ? Unsolder the motor & check the windings, any two wires should have the same resistance, also check that none of the wires are S/C to the motor chassis. At the same time check the 40 volt supply to the motor without the motor load.

Colin.

[DOFFERY]

Was there any result to the above thread? Would be nice to know.

Colin