Technics SP10 MK3 Restoration


Just got my SP10 MK3 base (motor unit & controller) back from JP at FidelisAnalog.com
JP is one of the most knowledgeable on the SP10 MK3 and is the one who designed and manufactures the MN6042 Speed Control chip that keeps these and other Technics turntable models still operating.

My SP10 MK3 came with the stock Technics SH-10B5 faux obsidian base.
It has very low hours of use , no signs of wear at all on the bearing and not a single blemish, other than some specs of dust and a couple spots on the copper part of the platter that need cleaning.
but I would like to have a 2 arm, constrained layer plinth built and have the motor unit mounted 'naked'. I am presently searching somewhat 'affordable' plinth builders and suggestions would be greatly appreciated.

The work that JP did to both the motor unit and the controller:

1.       Pre-refurbishment measurement to baseline the performance of the unit and to see if there are any underlying issues.
2. Cleaning of all PCBs to remove the factory conformal coating. At~40 years this coating tends to become hygroscopic which can cause stability issues.
3. Physical inspection of all solder joints under an inspection microscope. Many of the joints will exhibit annular deformities which can lead to joint fractures down the road. These must be cleared of the factory solder and re-soldered. There will also be poor joints that need the same treatment. You can’t just reflow as the solder alloys aren’t the same which can also cause joint failure down the road.
4. Electrolytic cap replacement and rectifier diode replacement.
5. Disassembly and cleaning of the motor. Bearing inspection and service work. Proper Anderol 465 oil is used for reassembly. Motor is then checked for any areas of bearing drag.
6. The brake solenoids typically needs cleaned, and band tension is adjusted.
7. Stop/start and speed selection switches in the motor chassis are measured for contact resistance. Too high of resistance is indicative of a switch failure in the future. In the control unit I typically replace all the tactile switches, and the start/stop switch if needed.
8. Relocation of the brake regulator transistor to the heatsink to prevent overheating of the board (factory design flaw).
9. MN6042 replacement installation.
10. PSU ripple check at all critical stages (10).
11.   Course calibration is performed and post-refurb baseline measurements for FG spectrum, motor drive phases, etc. are taken.

12.   After 48-hour run-in final calibrations and verification measurements are performed.

The basic service returns the unit to factory or better specifications (assuming no permanent bearing damage has occurred).   This service is quite exhaustive and very different from the typical work I see of just swapping some caps out, checking some voltages, and adjusting phase tracking.

The advanced service adds on top of the basic service:

1.       Replace all polyester capacitors.
2. Replace drive circuit metal oxide resistors.
3. Replace all voltage regulator ICs and update circuits.
4. Replacement of certain diodes.

Rick


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Showing 14 responses by rich121

chakster

I think that OMA only sells the ridiculously expensive caste iron plinth  ~$10K and even if that was 'affordable' I don't think I would want it.

I think the Steve Dobbins slate plinths are up there too in price, plus I have read a few threads where recently people have preferred other materials to slate.

Hoping to find someone who could at least CNC the separate layers of a plinth out of high quality Baltic Birch with a top plate out of Panzerholz and let me finish it.. or better yet... and I could put it together and finish it.... whether or not I can find such is another story  :)

What are you using now for a turntable?
Was out for the weekend.

Everyone, thanks for all the informative posts... so much to read here, again thank you!
@jperry
Thank you for the suggestion and the shop is actually not that far from where I live in Washington State.

I filled out the web page information form and hopefully hear back from Mr. Harban.
@syntax
@chakster

Always love your posts and suggestions.
I am going to try to keep the plinth as simple and inexpensive as possible.
@noromance
Thank you for the suggestion.
I went to his website and sent an email but I got it back saying undeliverable...
I then filled out the form letter on his webpage hopefully that goes thru and he is still in business.
@lewm
I very much appreciate your offer. 
Have drooled over your plinths pics many times.
Will try getting something built and if I am unable and you still would like to help me I will definitely take you up on that offer  :)
@au_lait
Thank you for the suggestions. Very good to know.

As for Jonathan @ OMA, he lost all respect from me and many others in his first years of business.
On many occasions he insulted and otherwise turned away many people/friends in the hobby due to his arrogance and just plain rudeness, some who actually have posted on this thread.
He will not get my business.


@chakster

Of course he was nice to you... you were handing over $$$ and he wanted more of your $$$!

Conversations and interactions that I was referring to were non-business... they were interactions between 'hobbyists'

Enough already... not going to go there.





@syntax 

" I would not waste much money for such a box, whatever material. Why not using a vibration platform with it, Herzan or similar. Makes more sense"

I'm watching for a good vibraplane like you use :)
@chakster

My experience with Jonathan was personal... it was interactions and discussions with him/others as hobbyists... before those discussions, when he and I discussed his plinths, he was quite the different person.

I didn't want this to get negative... as I try to stay positive and enjoy this great hobby.
@chakster
I’m sure you can find similar threads on most other audio forums... I know from experience they are on AudioAsylum.
@lewm

Only the motor unit with cable needs to be mounted to the plinth, as none of the controls on the original face plate are needed/used... all control will be from the remote control.
I don’t think it to be any more difficult... just will need an additional layer of material to surround the platter as a top plate.

Also totally agree with the plinth needing mass, either slate or constrained layer panzerholtz/baltic birch or maybe even Delignit/Panzerholtz and baltic birch?


@solypsa

This is for a SP10 MK3 motor unit, not the MK2.

The MK3 is fairly easy to mount nude.

Rick