Vintage DD turntables. Are we living dangerously?

Lucky enough to procure not one but TWO Denon DN 308 Direct Drive tables from Mexico.  Now there is a DD table, had one some years ago which I restored, its now spinning Records at kftool s place on the east coast.

These two will be "GrooveMastered" too, somewhat of a challenge as the motor is the size of a gallon paint can but I'm sure I can figure out something aesthetically pleasing.

Good Listening 


Peter

http://pbnaudio.com/audio-components/audio-turntables/groovemaster/groovemaster-vintage-direct

Norm, A few questions:
When you press your ear to the platter mat, I presume that the platter is not rotating. Correct? (It would be quite a trick to put your ear down on the mat with the platter up to speed.)
The hum: is it a constant or intermittent?
You say the "wall voltage" measures 102-103 VAC.  I presume you mean this is at the output side of a 120 to 100V step-down transformer, if you live in the US or any other country with 120V standard.  If not, what?  
And in connection with the last question, are you sure your TT101 is set up to receive 100V? Most are, but at least a few (mine included) were sold with selectable taps on the power transformer primary such that one can feed the motor with 240, 120, or 100V.  Check that the wall voltage and the transformer voltages are copacetic.

Hi Lewm,

Yes, the platter is stationary where the constant hum is travelled up to the platter mat.

I'm in Canada where 117v is standard. I'm using an Elgar 600A power conditioner adjusted to the unit's minimal output voltage setting of 103VAC. 

There is a diagram on the TT-101 transformer depicting 100vac as primary and 2 x 16.5vac / 1.2a, and 10.0vac / 1.0a as secondaries. 

I've replaced all the capacitors (8 in total) on the PS board in hopes of curing the hum. No luck. However, the speed fluctuation that I was experiencing earlier seem to have disappeared with the new caps.  

Following other TOTL DD designs, I've decided to move the xfmr into an external chassis.  I'll post my results when this is done.   

I'll leave this to JP or someone else with more expertise, but I have to wonder whether using a power conditioner and not per se a step-down transformer could have anything to do with causing the hum that you perceive.  Obviously, yours is a standard 100V unit.

In the longer term, you would want to replace ALL the other electrolytics, as well as those on the Power Supply board.

norm, 

Are you certain the Elgar unit is working correctly?  I see that it's advertised as having sine output.  I'd try a simple step-down as a sanity-check, à la https://amzn.com/B000WMK6QY.

According to the literature the transformer in the 101 is a potted toroid.  If that's vibrating, something is VERY wrong.

JP