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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
sonofjim
557 posts
 
Pryso,
My system pictures are so out of date that I've considered just taking them down. Both those tables are gone and have been replaced with a pair of Thalman redone MKllls. One is in Chris Thornton's large constrained layered plinth, the other is in the Dobbins plinth utilizing only the platter and motor unit. Both plinths are dual armed. I'm still in the process of setting all this up and may get around to posting better pictures at some point when finished. Tonearms are EPA 500 (6 different wands), an exotic German carbon fiber arm, SME 312s Magnesium and soon a 12" Reed 3P.
Lewm,
I wasn't aware of this mklll mod Bill is doing until now. Please post all you learn on this especially if you have it done.
lewm
13,270 posts
 
Dear Jim, Albert made me aware of it in the course of an unrelated exchange. At the time, his Mk3 was in Bill's shop to get the actual work done. Like you, I at first had no idea what Albert was talking about. In the interim, I visited Bill in order to pick up my CDP (sadly unfixable), and I got a technical explanation of the mod from Bill (see above, although I still have no idea what is done inside the PS module). At this point, Albert has the Mk3 back in his system and has had some time to evaluate the results. He really should be the one to say, but I can provide hearsay evidence that he likes it a lot. Apparently the ideas come from a third party who provided the wherewithal to Bill.

I am interested to read that you were able to mount an EPA500 with a Mk3. I will guess that you use it on the Dobbins' Mk3, because as far as I can tell it cannot be mounted with a stock Mk3 chassis; that big square escutcheon would get in the way; maybe not if mounted in the "primary" position, along the R edge of the escutcheon. (I own an EPA500, but I despair of using it with the Mk3; I want my Reed to remain in the primary position.)

Hey Halcro, Sorry I appeared so defensive. I was trying to be funny. At least we agree on direct-drive uber alles.
halcro's avatar
halcro
2,664 posts
 
No offense Lew,
I enjoyed your response.
Have you mounted your FR-64s yet
lewm
13,270 posts
 
It will go either on the L07D or the Mk3, in either case as a secondary tonearm (meaning mounted at the rear). In either case, I first have to create the mount. This is certainly one way in which the plinth is a pain in the arse. Right now I am having too much fun listening to what does work.
sonofjim
557 posts
 
Lewm,
The EPA 500 is now on the Artisan Fidelity plinth done by Chris Thornton. The main advantage of this arm system is it's flexibility. I got it to try multiple vintage/affordable cartridges. Currently I have five combinations set up that can be interchanged in about 30 seconds. It runs counter to common thought on these forums with it's limited adjustability(azimuth) and mutiliple connection points. You'd be surprised how good it sounds though. That being said, the modern premium arms are better of course. I'm anxious to try the 3P, possibly with an Allnic Puritas or Miyajima Shilabe. Now I'll forever have this mklll mod idea planted in my head too. It never stops does it?
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