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


128x128Ag insider logo xs@2xrich121
Quote
" I dont like plywood or panzerholz because they are dimensionally unstable in the long term - warping, expansion, contraction"
:::::::::::::::::::::::::::::::::::::::::::::

Thats kind of both true and false in my experience. For large objects like a plinth and platforms it false. For smaller objects it is somewhat true like in a tonearm. I have large pieces I have been using that I got from work when the plant was moving.
Came from machinery delivered and made in the60’s from Germany as skid and protection plates . After the machines so large they were floated on air in place the plates were removed and sat in a cold basement in winter and hot and humid in summer since 1962. I got them in 2003.
No checks cracks or warping and straight as could be. Apparently on smaller items like tonearms n such  the fibre structure is compromised.
This is copied from morningside....

"With standard products, like Panzerholz, much thicker laminations mean there is less stability when using the product on a very small-scale. When you release the confining tension of various layers, above and below, natural wood fibers will start to relax somewhat. *This is not a problem with large objects, like plinths, or bullet proof doors, * "
........................................
I’ve used it in numerous plinth builds , seen it used for engineered self supporting stairs in high end loft conversions etc.
Structurally its a very sound material. Ive not experienced the stability or cracking and warping at all that you’ve seen.
The pieces I had and have were 5 ft by 1.5 ft by 35mm thick . So much resin , not sure it really could be called birch wood anymore. Its a real blade and bit killer when cut to low or too high an rpm.

Apparently Pica wood is much better for smaller objects as its thinner cross lamination is specifically in a way to maintain its strength over a much smaller dimension. I’ve not used it so I can’t say from experience . Panzerholtz was my choice because I have never felt Aluminum was a good choice other than its ease of machining and once cheap price and after reading the specific tests done I pushed forward with what I had. I’ve seen other and heard other’s choices too. Its a matter of your design and materials at hand and what you like n want personally.. Lots of good results. I’m curious about the ebonized bamboo ply you mentioned as it sounds like another viable option to look into.
Choice is a good thing.

Although looks are very subjective, few could argue the skill, time, effort and cost of machinery and materials some of these plinth’s take to design and
build as well as business costs. Let alone the results. a "300 dollar plinth"... thats basically a board with a hole in it. Cheers

https://www.lessloss.com/page.html?id=80


Russ at Layers Of Beauty is excellent and priced better than most. I built a 2 arm panzerholz plinth with the drain etc for my SP10 MK3 (also dialed by JP) and when I needed advice Russ was a truly great guy and helped me. The panzer cost me about 1k all in, about $50 for some maple veneer, and the rest is all elbow grease, lots of it.

Cusworth plinths can also be made to order, all hand planed, can be as simple or novelty as you like, albeit more popular for older idlers. Check Audio Grail for examples.

Personally I would never give any money to OMA. All ego and hype, and that stuff looks steampunk. Maybe it’s not “just a wood box” but cmon, it’s just as ugly; weird corners, weird edge lip, hideous large logo, looks like a piece of shrapnel.

If you want not expensive and not wood, snd have some patience searching, you can find an old Lead Console by Osaka Canle Co, here’s one (you can find w/ 2 arms) https://youtu.be/oagZKxwmC8E

Or there is this: https://www.instagram.com/p/CG-40OXpE_-/?utm_medium=copy_link
@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.


It’s all a matter of taste after all. Someone may like the old lead console made in Japan in the 70’s, but It’s just another very simple metal frame. Back in the 70’s/80’s this company made lead consoles for Sony, Technic, Denon and others. I think it’s nothing special and custom made plywood plinth could be better.

Regarding OMA, again, Most people look at this company as “something beautiful” regardless of price as very few people can afford OMA products. But their plinth priced just like any other premium plinth from well known manufacturers.

Reading a negative posts about OMA I must admit that I have personal experience dealing with them about 5 years ago and my experience is very positive! He’s a dealer or Schroder, Ortofon, Miyajima, Schick, SoundSmith ... I bought my Schick “12 inch tonearm and Ortofon SPU cartridge from OMA for my Technics SP10mk2. Jonathan personally replied to all my email and answered all my questions, it was very helpful. In fact his price eas cheaper than German price for Schick tonearm so it was a very good deal. It was excellent service, no rudeness at all (I have no idea what you talking about @rich121 ), I asked so many questions and got all the answers, Jonathan was very helpful, I even tried to buy his demo Miyajima carts few years later and we tried to negotiate about the price, everything was nice and smooth like it should be. Compared to many other well known dealers I tried to communicate by email at that time asking questions, Jonathan was the best! This my experience with OMA, I had to say that, let’s be truthful.

I can imagine that some people may not like what he think about Direct Drive turntables (his preference is clearly DD and this preference is not popelar in high-end community). Regarding his own products it’s easy to watch his videos where he claimed they are not a typical high end company. So do not expect them to sell you what you can find in a typical high-end store.

Their demo loft is beautiful and some of his speakers, stands, plinths, amps are beautiful and made with a great passion! He’s got a well educated designer or design team that other high-end companies can only dream about.


His stuff is art, it’s nice to have an independent company like OMA today. He’s doing a geat job explaining people on his youtube channel a lot of things about history of audio (horns, tube gear, turntables). He’s doing it not for audiophiles, but for younger people. His showroom in NYC is open and anyone can come, you don’t have to buy! This is great.

@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.