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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 7 responses by dover

dover
2,177 posts
 
I dont like plywood or panzerholz because they are dimensionally unstable in the long term - warping, expansion, contraction.

I have had excellent results with Engineered Stone ( 95% plus quartz for premium quality european product ). There are many kitchen benchtop manufacturers with the requisite CNC machines to ensure accuracy at modest prices, particularly if you use offcuts which most have from large jobs.

I have also used Ebonised Bamboo ply, this is a high density bamboo ply ( over 50% heavier than standard bamboo ply ) - it is 50% harder than maple. In this case I did the CAD drawings myself, and used a CNC contract cutter to do the cutting. You need very sharp quality router tips or blades to cut this stuff cleanly.

Both of these are relatively modest in price if you do the construction yourself after outsourcing the cut materials.





dover
2,177 posts
 
@chakster 
Your posts above 07-24/25-2021 would have to be some of your most ill informed posts ever, even by your own modest standards.
Artisan fidelity plinth for Technics is also “just a box” (even if the wood is nice). 

No its not. the Artisan Fidelity plinth is a sophisticated constrained layer plinth using panzerholz and other materials and includes a drain block for the main bearing.
OMA Graphite plinth are beautiful and designed by professional designer with a good taste! 

No - the plinth in the picture is a slate plinth, not graphite.
Not sure if you are aware but one is a metamorphic rock with structured layers, the other is a mineral, a form of crystalline carbon quite soft.
The properties of each material are quite different.
Basically a plinth is just a plinth, 
No. The plinth construction and materials used can materially affect the overall sound of a turntable motor. I do understand that you might struggle to hear any difference with your knackered old 80's MM's that you think are state of the art.
Luxman PD-444 comes in super heavy aluminum stock plinth 
No, its a weetbix sandwich that uses magnetic steel plates, wrapped in thin alumium foil.

You seem to listen with your eyes, not your ears, and prognosticate at length on items you have clearly never heard and have little or no understanding of, as evidenced by the posts above.

 

dover
2,177 posts
 
@chakster 
If you like boxes like this then I doubt you have a good taste.
If you read my post correctly above, I have already said that I dont like panzerholz, timber, plywood etc because it is not dimensionally stable.
If you like boxes like this then I doubt you have a good taste. 
As Salvador Dali said - "It is good taste, and good taste alone, that possesses the power to sterilize and is always the first handicap to any creative functioning"
 If you actually read my post above I make my own plinths using either ebonised bamboo or engineered stone - nothing like the Woodsong/Artisan Fidelity plinths. 

You can continue to post your absurd about vintage MM cartridges, but I’ll tell you that when SP-10mkII was in my system my cartridge was this ZYX Premium 4D SB2 (it’s $5k modern LOMC) and Airy 3 with silver coil (another $3k LOMC). At the same time in MM arsenal these two beauties with EPA-100. Am I missed something? 
Yes, a decent turntable.

dover
2,177 posts
 
Just watched this with better view of OMA Cast Iron plinth, and to my surprise Jonathan (at 5:10) said that there is a CRYSTALLINE GRAPHITE in this grey iron formula.

This is like mounting a bowl of jello on a 20 tonne rock.
If you have ever seen the guts of a Technics SP10 you would know that the case is flimsy, and the motor mounts and stator mounts are almost as bad.

The best thing you can do to a SP10 is remove and disassemble the motor, bearing and platter and re-engineer all the mechanical mounting points and pop into a rigid plinth as in the Kaneda mods and the original OMA Slate plinth.

Seems to me the new OMA plinth is based around removing the time and cost of gutting the TT as in their earlier solution.

The OMA plinth is just a fancy picture frame. Come on - you spend all that money to eliminate resonances and then use wood for the armband - of course each wood has a different sound - bit like buying an ice cream - what flavour would you like sir ?

The rest of their presentation is like a Barnum and Bailey circus -
Cant pronounce Technics correctly
Claims the SP10R is significantly better than the SP10mk3 - LOL - of course the scarcity and age of SP10mk3’s would have nothing to do with their opinion !

You have to remember their market is lunatic billionaire New Yorkers who have never heard a decent stereo, but want something unique - in the looks department. Their mobile ring tone is probably bling bling.



dover
2,177 posts
 
@pindac  

Checkout warrenjones SP10 appreciation thread on stereonet.
There is some very interesting information on checking motor runout, platter runout, new platters - there are significant opportunities in checking tolerances and blueprinting the SP10 motor, bearing and platter as part of your build - big gains to be had.
dover
2,177 posts
 
Toho plinth -

 I discovered vintage TOHO cast iron plinths online. I don't have technics Sp10mkII anymore. But Toho plinth for Victor TT-101 is interesting (not so big and not so heavy).  

What happens when the cleaning lady, sorry - non binary cleaning supervisor, decides to clean under the arm pod and forgets to tell you they moved it.

Answer - a year later you wonder why all your favourite records are mistracking.

I subscribe to the loop rigidity principle - platter, bearing & arm mount must be absolutely rigidly locked together in position  to measure the groove accurately. Arm pods in my view are only as good as what they sit on, and often will compromise loop rigidity
dover
2,177 posts
 
Pindac
If by denified wood you mean panzerholz or lignostone then it is not stable. The stuff bends. You would need to anchor it to some other material or structure to prevent warping over time.
I have seen some very expensive plinths that use panzerholz, and over time, you can see they are starting to come apart. 

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