Yamaha YP-D71 Turntable Sync Lock Problem

[Stockman]

I feel lucky to have one of these beautiful (and hefty) turntables. Unfortunately is has slowed to a crawl. Rotating the platter by hand revealed a lot of friction, so dribbled some Turbine Oil behind the sealed motor. It is now up to approximate speed but sync lock light is intermittent and audio is definitely warbling. Since the motor is sealed, it's hard to know if there additional lube points, but it seems like it's a speed control issue. Does anyone have any suggestions as to a possible solution, other than dropping multiple ducats at a service center?

 

[vinyl fiend]

power supply maybe?

 

[Balifly]

but it seems like it's a speed control issue.

Does anyone have any suggestions as to a possible solution, other than dropping multiple ducats at a service center?

Try De oxidating the speed controls.

See the following thread:
http://www.audiokarma.org/forums/in...diots-guide-to-using-deoxit-revisited.207005/

Here is a link to the service manual:
https://www.vinylengine.com/library/yamaha/yp-d71.shtml

Spray and exercise all the power and speed switches, especially the speed control VR1 and VR2.

 

[Stockman]

Thank you. I did have the service manual, but was hesitant to adjust VR1 and VR2 because I don't have a scope. With your encouragement, I marked the existing settings and Deox'd overnight. That, combined with oil behind the back of the motor has fixed it!

 

[scottdavis08]

Having same problems as mentioned above, so I gently pulled the 2 controls for speed and play. The play mechanism has a spring and a white circular something that’s now floating at the bottom of my turntable. I had no idea I was going to break a knob mechanics when I pulled this off to spray deoxit. This turntable is turning out to be a big disappointment for me!

 

[Stockman]

Ouch. Hate to say this but those two controls were probably not the problem. For me it was the two stand-up trim pots on the circuit board that needed cleaning (mark their positions before twirling).
If you haven’t already, look at the instruction manual and follow instructions to remove bottom panel. You should then see the guts of your speed and play switches.. and figure out from there. I never took them apart, so maybe someone can assist with that.

 

[JP]

VR1 and 2 are not speed controls, they adjust the phase relationship of the PLL.

On simple F/V and similar type servo tables cleaning actual speed control VRs is rather harmless as a troubleshooting step as those are easy to adjust back with a strobe, etc. On quartz-locked tables the adjustments are so fine that no physical marking of position will ever put things back the way they are supposed to be.

 

[Powertech]

On simple F/V and similar type servo tables cleaning actual speed control VRs is rather harmless as a troubleshooting step as those are easy to adjust back with a strobe, etc. On quartz-locked tables the adjustments are so fine that no physical marking of position will ever put things back the way they are supposed to be.

In order to set these units you need a dual trace oscilloscope and a breakdown of the expected trace relationship. It's not something you can do by eye.
From the OP - You mentioned a grinding noise. I would look at the suspension system and the motor bearing. It sounds like something has sagged or got caught up and is rubbing severely enough to slow the motor down. The motor control system is probably O.K.