How to measure power consumption of DD2

I've been following Mikholms guide to repairing DD series walkman with great success. One thing eludes me however, setting the motor tension by measuring the power consumption. How do I do this, I mean, where do I actually take a measurement from with the multimeter?
I've tried putting the probes across the battery contacts with batteries intalled and pressing play - with the meter set to DC mA, it gives a reading of 1.2 which is miles away from what Mikholm suggests..... Hope someone can help

 

In order to measure current, you need to connect your multimeter in series with the power supply/batteries. If you choose to do the measurement with batteries in place, you will need to desolder one of the wires going to the battery tray and connect the multimeter in series: one lead going to the desoldered wire, the other to the point where you desoldered it from.
However, note that if you put the probes in parallel with the battery, it is possible that you blown the miliamp fuse of your multimeter. If that is the case, the fuse will need to be reaplced (with one with same rating) in order to make measurements again.

There's something else I would like to add about that adjustement: contrary to what it is said in that tutorial, this adjustment is not influenced by replacing the capstan ring.
This adjustment sets the flywheel thrust play (up and down), which is set by 2 parameters:
1. The thrust washer that sits between the flywheel and capstan bearing: if the thickness of that washer remains the same the play will be the same. Unless a different washer is fitted because the original was was lost, that thickness cannot change.
2. The thrust adjustment screw. This has lock paint from the factory so unless that is tampered with, the thrust play cannot change.

Wow&flutter is indeed influenced by the thrust play adjustment, as too little play will create drag. On the other hand, too much play will create speed variations when moving the unit around.
On DD units the thrust play should be about 0.05mm, so if you have a feeler gauge you can check/adjust it that way.
An even simpler way to check is to move the flywheel manually up and down: you should not feel any play, but at the same time the flywheel should rotate completely free, without any friction whatsoever (there is some friction in the bearing, but there shouldn't be additional friction).

From my experience, this thrust play doesn't usually need re-adjustment, unless there's a bent bracket or different thickness washers installed. It is very easy to decrease it without realising it, increasing wow&flutter and putting additional load on the motor, shortening its life.

However, there are another 2 adjustments that need to be done and are not mentioned in that tutorial (I should probably make a separate thread covering this):
- making sure the motor spindle is in full contact with the rubber ring, as it usually is in contact only 80-90% of the surface. If that is the case (I found this to be pretty common), it can be resolved by bending the back part of the motor bracket inwards.
- making sure the motor spindle is perpendicular to the flywheel This is done in 2 ways:
a. on units like TC-D5M, WM-D6C is done by moving the motor around with its screws loosened, as the screw holes are larger than the screws;
b. on most DD walkmans, there is an adjustment screw that moves the motor left to right: that needs to be adjusted until the motor is perpendicular to the flywheel; then it should be secured with lock paint or glue;

When the motor spindle is not in full contact with the ring, it can slip and create gauges in the rubber ring. This will increase wow&flutter or the unit may not work in FF/REW, where higher torque is necessary.
When the motor spindle is not perpendicular to the flywheel, operating noise and wow&flutter will increase.

 

That's the most comprehensive reply I've ever had to a question, thank you so much!
(The fuse seems fine BTW )

 

Spittin' some knowledge up in here!!

 

^ another good read ^ I do have a DD walkman, just one I think. I have not opened it since I have bought it from so many years ago, ever since the man that collected walkmans that lived in Florida passed away as he bidded under me John something I think.