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Technics SP-10 mkII speed adjustment question

Hi,

I'm on my way to complete my Technics SP-10 mkII project. Actually, a friend of mine, a professionnal audio technician, is working to upgrade the PSU, which is done but a small adjustment on the speed must be done and he need some cue on this issue.

We already asked Bill Thalmann, Artisan Fidelity and Oswald Mill audio. Plus, I'll post on DIY Audio today. We'd like to get the answer as quickly as possible to finalized this for the week-end. Hope someone on Audiogon can help.

Here's the message from my technician:

"Hello,

I'm an electronic technician and I do repair for audio equipments, vintage, hifi pro and more. I have a client here that brought me his turntable Technics Sp-10 MKII to fixed. I have a little question about it and he gave me your email because he pretended that you have some experience with this kind of materiel. So, hope that you can response my technical question.

I replaced all capacitors in the power supply and a big solder job. I checked for defect solders or capacitors on the circuit boards inside the turntable and I tied to do the adjustments . Everything seem good right now, the turntable work fine. I tried do do the period adjustment with the VR101 and VR102 potentiometers like in the service manual ( see attachment, Period adjustment method). When I looked the stroboscope at the front of the turntable, It's pretty stable but I can see a tiny rumble at 33 1/2 and 78 speed. 45 is the more stable speed for the stroboscope. So, I fixed the phase reference with T1 at 18us of period and I try to do the period adjustment at the point test T and S on the board with the O point for reference. When I put my scope probe on the T point, I can observe the stroboscope running. It is not stable at all. If I pull off my probe, the stroboscope is stable again. So When I have the 2 probes at point S an T at the same time to do the adjustment, it's impossible to fixed the wave T because it going right to the left on my scope. When I turned the VR101, the T wave going faster or slower but never stable. I tried to ground lift my scope, plug it into the same power bar and try to pull off the reference at the O point. I can't have a setup that I can see a stable T wave in my scope with the one that I can do the right adjustment. Why? Is there a problem with the turntable or maybe it's a incorrect probe or ground setup? Please let me know what you think.

Best regards"

Thanks for help,

Sébastien
128x128sebastienl
pryso
1,928 posts
 
Hi Lew,

Now I'm confused. What I'm asking about is the cast metal frame that surrounds the platter, and in the case for the Mk 2 and Mk 2A provides support for circuit board attachment from underneath. Since I've never seen a Mk 3 except in photos I'm not sure about it. But from the top it appears identical to the Mk 2 and Mk 2A. This is what I understood you to mean by chassis.

The Vintage Technics site, which of course is not infallible, states the SH-10B7 plinth was intended for both the Mk 3 and Mk 2A mounting. The opening in that plinth is indeed not round. See this from Vinyl Engine -

http://www.vinylengine.com/library/technics/sh-10b7-obsidian-plinth.shtml

What I'd like to know is if the cast metal frame for the Mk 3 is different from the Mk 2A? That is, were additional vibration damping methods applied?
dover
2,243 posts
 
Yes
Not really
lbelchev
64 posts
 
Lewm, When Technics wrote "sophisticated cabinet construction" they were referring to the chassis proper of the Mk3 only. Look at Halcro provided link from a cross-sectional view of the SP10Mk3 (it's from the same Technics MK3 brochure).
chris74
99 posts
 
"I will leave it to Audiogon members to decide who copied what. Take a look at ads and dates."

I believe there may be some misunderstanding here, allow me to clarify.

People often serve as inspiration but rarely can single individuals claim to be the emperor of all. This case bears no exception, as you yourself designed a plinth which was obviously inspired by the exterior lines and angles incorporated into a much older existing design developed originally by Technics for the very SP10Mk2 and Mk3 models that you and I, amongst many others, so passionately continue to covet. I do not wish to, nor has it ever been my goal to invalidate or diminish your own efforts (publicly or privately), however, since you continue attempting to stigmatize my own design efforts on public forums, I will then rightfully respond. True, you may have been the primary source responsible for bringing the Technics SP10Mk3 back into the community spotlight is not the contention and I believe I have already acknowledged this. The timing aspect of offering an updated revised version of the SH-10B3 style plinth, apparently is. Yes, indeed your plinth baring this form did reach the marketplace first. However, neither you nor any member here can claim that another SH-10B3 shaped plinth was not also in the developmental stages by Artisan Fidelity during this period of time. My design, inspired by the original factory design and thereby "your" design is quite different however (as mentioned previously), in its internal constraining layers, materials and implementation of these as a whole. The balance in terms of presentation is quite different, this much I can assure you, as I have spent enough time personally listening to your plinths sent in for repair to know first hand. People learn from other people and that is the beauty of the game, this does not have to be a competition. In all fairness and for the record, you took some of my ideas and I took some of yours and we learned from each other. For those members not aware, over the course of the past year and a half, we have had several A. Porter plinths in for extensive repair as a result of the Ebony plank wrap severely splitting apart along all sides. It was not long after this, that A. Porter began building his plinths with much thicker plank wrap, obviously as a preventative measure against cracking, this same practice has been employed and advertised by Artisan Fidelity from the beginning, then later copied. I see another more recent practice of yours, the advent of chassis refinishing/coating, platter refurbishment and even more comprehensive restoration services which have been employed, again these such services have been offered by Artisan Fidelity from the start.

These will be my final comments regarding this issue on this thread. I would ask though that you please refrain from continuing to chastise our products when in reality we continue to respectively move in different design directions.

I think its time to bury the hatchet.

albertporter's avatar
Ag insider logo xs@2x
albertporter
4,949 posts
 
Bury the hatchet would be to drop the subject since my last reply was short.

Additional short answer is my plinth has no relation to the stock Technics plinth other than the radius around the perimeter.

Your's on the other hand copied our iron block and rod, recessed chassis, arm board design, rubber grommet and plate outlet for umbilical cable, metal interior plate sandwich to Panzerholz and pretty much all interior and exterior dimensions.
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