Turntable speed cap value

[Guitarist]

I have a Akai Ap-D30 and I did replace one of the caps, a .47uƒ but the speed wobble and slowish problem persists. Do you think the other values, which a pair reads 3.3uƒ, are critical? Because I have lot's of 5uƒ around. It for the speed control circuit so maybe they're just filtering the DC power.

All pots are cleaned.

[mozz]

If there is a switch to change speeds, be sure that is cleaned also.

[dmeek]

This is a direct drive turntable so the motor control is fairly complex.
Definitely the first thing to do is clean the speed switch. pitch pot,
and the Quartz Lock switch.
Is it wobbly in Quartz Lock mode? If so you are probably out of luck.
Maybe check the main filter caps.

The service manual is here. You have to register.


https://www.vinylengine.com/library/akai/ap-d30.shtml

[olddawg]

You probably need to replace ALL of the electrolytic caps. I’m not a big fan of shotgunning.. but with old consumer electronics it’s usually the first thing you do. They dry out. Especially smds. You can mess around with an ESR meter but it’s usually faster and better just to replace them. If you still have a problem them you troubleshoot.

[Guitarist]

Alright thanks and apparently I'd already resisted with VinylEngine prior!
Do you think that I could swap in the 5uF for the 3uF caps, might they be close enough? They're in the middle of the att. schematic.

Also with the power supply caps, besides looking for that proper -14.5V can I set my meter to AC and measure for ripple between power and ground? If it less that .02Volts AC then that would be minimal ripple perhaps? I've kinda played with this approach with tube amps but not sure of its efficacy.

Thanks, still learning...

[olddawg]

If you don’t have a scope measure from positive to negative with your meter on the AC scale not chassis ground. I would order 3.3uf.. that’s the standard value nowadays and cost really nothing. I hope you lubricated/oiled the motor bearing and cleaned the speed adjustment pot with some Caig. I was an Akai factory authorized tech when this thing was made. The problem is usually small electrolytic caps. If the power supply caps are bad it will be obvious. You can always parallel another cap across one for test. It’s old. The motors do fail too.

[Guitarist]

Well I live in the country and and new parts are scarce so I swapped in a pair of 5uF caps. But also inserted an additional 2.2KΩ at R16 which adds some "headroom" to the speed adjustment (only bothered with the 33 setting as won't be spinning 45s). I see a tiny bit of wobble on the strobe but the platter also isn't perfect. So good enough to rock from here on, thanks!