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

Showing 3 responses by chris74

We also do not provide free technical service but referred the OP to a certified technician we recommend in Chicago for advice. Our certified technicians are not available for free technical advice or assistance. In the event the OP should decide to send in his Mk2 for service, we would obviously be able to repair/service his unit accordingly.

Christopher
Artisan Fidelity
"As for Artisan Fidelity, their plinth is a copy of mine and I resent that." Not so fast. Although Mr. Porter's tale makes for good story telling, anyone with a fastidious eye for detail and a keen memory should be able to spot immediately what classic Technics design was the near aesthetic duplicate of "yours". For those interested in investigating further, search Technics SH-10B3 Obsidian plinth on Google. Once a suitable image is located, note the familiar beveled edge angles (top and bottom) and armboard location and shape. Now, if one were to imagine this plinth's center slightly taller and a slightly longer armboard.....you get the idea. An original exterior design, yes, only by Technics circa 1980 or so. This base criteria also served as a personal design concept of mine on paper, long ago. Constrained layer damping in mechanical engineering is a practice which has been utilized in various industries, even audio for decades. Panzerholz, again, not invented or conceived by the poster above. Furthermore, the internals of these two respective Sp10 designs differ substantially. The method of cld layering, applied isolation, bonding, materials used, finishing techniques and implementation as a whole vary to a significant degree. The principal similarities of the plinths in question are almost solely aesthetic in nature. While we are sharing openly, inquisitive readers might also be interested in researching Artisan Fidelity's once unique practice of thick outer plank wrapping over a constrained layer core. This practice has been embraced by AF from the start and only later copied by certain others. If anyone is curious as to why another might suddenly switch their approach from thin to thick panel wrap, just ask, the whole story is an enlightening one, that much I can assure you. And the sudden offerings of Sp10Mk3's with aluminum chassis refinishes? A "copy" perhaps of our long standing practice or merely coincidence? The list goes on, but why bother....

Where credit is due on Mr. Porter's behalf, in my humble opinion, lies in helping bring to light the vast potential of these particular direct drives of a bygone era, the Technics Sp10Mk2 and Mk3 which were once overlooked by many, primarily as a result of poor implementation. (ie. plinth design) In this capacity, this individual has served as an inspiration to both myself and others. This includes the fundamental approach of Panzerholz core based plinths in conjunction with the above stated models.

Artisan Fidelity's core substratum methods employed for Panzerholz based and conventional style plinths have been proprietary since day one for each individuals set design requirements and tailored uniquely for each make and model. For anyone following our work, never have our aesthetics for the Technics Sp10 remained static and based solely around the vintage factory SH-10B3 Obsidian plinth or "Porter" style in question. Moreover, our latest Sp10Mk2 and Mk3 next generation design efforts build upon knowledge learned through previous conventional design approaches and are a significant departure from either.

Never has Mr. Porter made an effort to approach me privately regarding his feelings on the Sp10 plinth style matter, instead he wishes to continually express his thoughts in a contriving manor on public forums. Perhaps had he contacted me early on, and made the choice to discuss things directly like a professional, as a like minded audio enthusiast, we could have avoided these unpleasant and unnecessary forum antics.

Time to put this to rest.

"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.