Attempting to revive a Grundig Console TT

[Exee]

I bought a non working Grundig tube console at the end of last year for the stand alone amplifier as my first foray into the world of tubes. That project is now happily complete, and I am happily listening to it's 8W of PP goodness.


Now I want to get the turntable working and make a fun little stand alone unit to play 78's. The platter spins, but very slowly. I figure I need to oil the spindle and the motor, but I can not figure out how to get the platter off. Youtube has several videos of this TT, but each skips over how to pull the platter.


I also realize, that I may need to add a bucking transformer or some other motor control as it is designed to run off 110V.


Images below of the top of the unit, the added furniture feet, and a closeup of the spindle.

 

[PRR]

There's a "circlip", a steel split ring in a circumferential groove. Work it around until you can see the split in the vertical groove (it's already there). Work a tiny screwdriver behind the clip and work it out of the groove, a little at a time going around. Try not to stretch the circlip, though in this case it's not real critical.

The voltage is a non-issue. The motor speed is locked to the 60Hz line. A higher voltage (125V) modestly increases the maximum torque, but a turntable never works at max torque.

(Technically, "CirClip" is a trade-name for a C-clip with fancy ends. Yours is one of many simpler types.)

 

[as_audio]

Depending on where you live you can set the voltage selector under the platter.

 

[Exee]

Thanks for all the help! Platter is off and looks like the idler wheel is still in good condition so I am hopeful a little grease / oil and it will be happy. Now to decide how to match the output impedance of the old ceramic cartridge (Telefunken A20/2 or A22/2). I found replacement needles, but if the cartridge is dead then replacement and rewire might be the best option.

 

[Exee]

I finally got around lubricating the turntable. I greased the motor and the spindle and the teeth of the speed selector switch. It spins better, but I must has reassembled the motor incorrectly as it now spins the wrong way. It looks to be a simple AC motor. All speed control looks to be based on motor shaft diameter ratio to the idler wheel. I did not disconnect any wires so it must be something simple.

 

[Galu]

This is likely to be a 'shaded pole motor'. The direction of rotation is determined by a 'shading loop' around part of the stator of the motor. If you got the stator upside down on reassembly, that would account for the motor reversing direction.

 

[Exee]

That was the issue. Now that it seems to spinning correctly I need to figure out how to get sound out of it. It has a ceramic cartridge, but the output is very low and has a significant hum. Same with another ceramic cartridge I found that fit the TT. There is an RC network on the output just before the RCA cable. Perhaps the 4700pf cap is gone? I will report back after get those replaced.

 

[dhaen]

Ceramic cartridge output should be high, so if another gave the same result the the problem is elsewhere. If it's humming, one lead may be open circuit.

Also, is this a rim-drive turntable? If it is then the major failing is the deposit left inside the rim by the drive wheel. I expect though that you've cleaned things well.