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
Sebastien, Glad you are pleased. I am quite sure that the CU180 would be a big upgrade vs the OEM rubber mat. (Almost any not-rubber mat would be, I think.) Albert will speak for himself if he disagrees, but I do think he now uses the Boston Audio Mat2, on his SP10 Mk3.
Hi Lewm and Sonofjim,

Yes, I'm considering the purchase of the Boston Audio mat 2 for the future to compare it with the Micro-Seiki CU-180.

Sébastien
Hi Sebastienl and other A'gon members,

Do you care to share information on where to get the Micro Seiki CU-180 ?

Thx in advance.
Hi Tagheuer,

I bought my Micro-Seiki CU-180 from 2juki, based in Honk-Kong. He is a regular seller on eBay and already sold on Audiogon. I also bought from him a SME 312S tonearm and a Denon DL-103R cartridge. I was very satisfied with my transaction of the SME and the Denon. Good communication, fast shipping, extremely well packed and at a very competitive price.

For the Micro-Seiki CU-180, two persons reported that he already sold fakes one so I asked for pictures. It proves to be authentic with the original box and the Japanese sticker on the mat. It was described as "new in box" but I realized afterward that it has some light scratches on it, impossible to see them on the pictures. Finally, I judged it to be in very good condition, but it was not mint and it makes an incredible improvement in my analogue set-up.

Regards, and like Raul says, enjoy the music!

Sébastien
Lewm,
"With the modification to the stator mounts, there is less energy dissipated in moving the stators, more precise speed correction by the servo, and far fewer events that trigger the servo. Everything gets even smoother than it was."
But you questioned whether I could hear the error correction on the DD's, even on the "inventor" of these SP10mkIII mods system whose TT I have heard and am underwhelmed.
Halcro,
You need to denude yourself and go and sit on a crowded beach. Open your mind up. It seems clear to me that the gist of the suggestion was the amount of error correction could be reduced by providing a more stable mount for the stators or whatever. If you hear a difference from the removal of extraneous bits, as you proclaim, then why could there not be an improvement from altering the structure or support of those extraneous pieces and other essential components. Your use of referential authority in dismissing Lewms suggestions is not a persuasive argument. I sincerely hope that if you have had design input into bridges in Oz that you have considered the ground upon which they sit. I do have some dear friends over there.
Yo