It's very touchy - a micro turn of the adj wheel may cause markings on platter to start spinning considerably... ...Haven't looked at the guts of adj wheel either - if it's mechanical variable rheostat or strictly electronic.
You may be right about the pitch control being the prob. I can pop off bottom & see how it works. Some brands/ models used a idler pulley that moved up / down a tapered drive shaft (least on dir. drive). If it's electronic & can clean w/ contact cleaner, will see.
As someone that's worked on cars & electronics for decades, it'd really surprise me if a slipping belt only caused audible problems once in a great while.
I never noticed any introduced noise from the table...
If it uses an idler pulley, then it's not direct drive, right?
You mis-understand the concept of 'direct drive'. Your 1218 uses an 1800 RPM (4 pole) synchronous motor with a conical pulley.
The advantage is no vibration induced rumble.
Glenn - I didn't misunderstand the direct drive concept. But you're correct, the idler wheel design is a variation of belt driven, so technically it's not a direct drive. But it's not belt driven, either. That's what I should've said, "Idler wheel driven instead of belt driven." Thanks for pointing it out.
Jury's still out, but * appears * my theory may be correct - belt slip wouldn't cause such very short & infreq. pitch changes. Now on to issue of different cartridge - another post.
You could use contact cleaner. Poster in SH forum suggested naptha, though no idea why. I can see using it to clean grease, etc. off, but not as final step.
Use a dedicated contact cleaner, cause they also contain lubricant. I used Tuner 600 by CRC Kontakt Chemie and Philips 390 CCS.
Which / what type store(s) sells it in your area? Only electronics, or hardware / home centers, too?
eevan - A close relative is named "Evan" - I always suspected the name was of Russian (in your case, Serbian) descent - yes? Perhaps a variation of Ivan?
This Technics SL-B1 turntable - given by son - has very short (maybe 1 - 2 sec) & infrequent (1 or 2x / LP side??) changes in pitch - quite audible. It's one w/ a pitch / RPM adj wheel & strobe. Maybe this was a seriously cheap unit when new & basically P.O.C. No idea. Never had a pitch problem w/ the direct drive Dual that my son borrowed the cartridge from, but then, it wasn't decades old.
Arnold, yeah, sounds like a grease spot on belt might do it. Wonder if played very long, the grease might transfer to capstan, then onto other areas of belt? Then would have intermittent pitch fluctuations. Depends on type grease & amt, I guess. Don't believe was the cause in my case.
Direct drive speed is maintained with a servo system totally independent of line voltage or frequency. Some are crystal referenced but as Dr Richard Greiner, UW Madison electrical engineering professor in the '70s said, "it's an elegant solution to a non-existent problem".
Quote from: Jenni28 on 23 January, 2011, 05:58:16 PMThis Technics SL-B1 turntable - given by son - has very short (maybe 1 - 2 sec) & infrequent (1 or 2x / LP side??) changes in pitch - quite audible. It's one w/ a pitch / RPM adj wheel & strobe. Maybe this was a seriously cheap unit when new & basically P.O.C. No idea. Never had a pitch problem w/ the direct drive Dual that my son borrowed the cartridge from, but then, it wasn't decades old.This exact problem can be caused by a grease spot on the drive belt.