DD-100 very very slow playback

Hey all. Just got my hands on a Boodo Khan Dd-100. Replaced the central gear as it was cracked. Followed Marian's guide. Assembled and found the playback struggles to engage properly and when it does, the playback sound is really slow. Adjusting the speed Pot does nothing. I double checked to make sure I assembled everything correctly. Done some DD's in the past so I'm sure I have assembled it correctly. What could this be? Bad motor, capacitors?

 

Could be many things (motor spindle slipping on rubber ring, hard to turn mechanism, servo problem), you first need to figure out if it's mechanical or electronic.
Fact speed trimpot does nothing would suggest a failed CX20084, there are situations where the symptom is slow speed rather than fast. But you need to check Vref and sawtooh waveform to confirm.

 

I tested out the motor. Replaced with one that I know works. Still very slow. Will try to find a CX20084 chip and might as well get some replacement capacitors.

 

All I can say that I have never had any luck with Boodo Khan's.

 

Been doing some fault finding. Found only 0.62v on the positive wire for the motor. Something is choking the volts but having trouble chasing down the culprit. With the wires for motor desoldered, I get zero volts on the + pad. Motor runs at high speed when I connect the wires directly to a single 1.5v battery.

 

Motor is controlled on the positive side, black is permanently grounded.
Problem is electronic given you have only 0.6V at the motor. You should have ~1.2V when running at the correct speed.

Next thing would be to check Vref (pin 5 - 1.65V) and sawtooth waveform (pin 4 - should have a DC voltage of 1V).

 

Not sure what happened but now the voltage is all over the place. Going from 0.6 to 1.0 volts. Motor is still slow but it is erratic. Pin 5 is around 1.5v and Pin 4 is 1.4v
This player will be the death of me.

 

Just replaced all the caps. Had a set of them on hand so might as well do it. Made no difference to the slow speed. I think I'll need a replacement CX20084. I'll just keep my eye out on a cheap DD. I do have a few DD's and a DC2 but not really keen on removing the chip from one of those just to test.