whats up everyone?!??

[manuele]

it s been a long time i was looking for a qualified 1200 and turntable related tech forum...& at first sight i must say you ve done a really good job mr. REVOLUTION!!

i d like do go more deep with the tech questions so here we go:

1) is a PPL kind circuit that controls the motor rotation?

2)Is the platter controlled by the same (x201) quartz oscillator either when the Quartz Lock Feature is enabled and the Pitch slider is functionally (and the Lock Feat. is off)?

3) What does "..the stroboscope is controlled by the extremely stable quartz oscillator, rather than potentially unstable AC line frequency." mean? When right after that they say : "The LED illumination is not syncronized with fluorescent lamps." wtf???

Hoping you will hit me back with some interesting answers..

thanx in advance

[Phonics]

hi

im pretty sure i that im talking out of I disagree but since this forum isnt all that active i will attempt to voice my opinion on your last question as the technical aspects of these turntables is far out of my league

3) What does "..the stroboscope is controlled by the extremely stable quartz oscillator, rather than potentially unstable AC line frequency." mean? When right after that they say : "The LED illumination is not syncronized with fluorescent lamps."

you most certainly already know this...but it is worth mentioning

stroboscope = red lamp dealy offering an indication of platter speed (or %change in speed rather)

the way this works to my knowledge is that you eyes pick up a certain ammount of frames per second and if the light is in synch with this speed, objects that are moving and arrive at the same spot (or an object that looks the exact same as the original object returns to the same position) and the light concentrates your eyes on this object via bursts of brighter light (like a camera flash) then it will seem as though it did not move at all (like a strobe light with a fan or car rims looking like they are moving in reverse)

the quartz oscillator's job is to keep this strobe action of the red strobe dealy accurate

this same strobe action could be accomplished via a fairly simple circuit (flip flop switch?(long time since grade 8 electronics ) i imagine but unstable voltage/other variables would be rather noticable with such an inaccurate mechanism, and thus should be avoided

the led's are unrelated to the strobe lamp i believe so i am not quite sure why this is being pointed out, perhaps it is because fluorescent lamps operate at 60hz (as they have no filament like an incadescent bulb would)so they function by electricity being given in bursts (60hz = 6000?cycles a second) which excites the atoms of gas in the bulb and makes them glow)

whereas LEDs operate at a constant rate (to my knowledge) which would not be affected by surrounding fluorescent lights?

that doesnt make much sense though...so i dont know...
my webcam has some environmental lighting cancelation built into it which eliminates shoddy looking 60hz lighting dissadvantages so maybe that is a hint as to what is being avoided somehow?

well
i hope someone else corrects most of what i said
and answers my question as to whether or not the tech1210m3ds can turn on directly into 45rpm mode

[manuele]

hi phonics
thanks for posting your help first of all,

so the answers (sorry for my nutsty english!!) are that the Stroboscope is controlled by the quartz oscillator due to its better accurancy, and the stroboscope s light is not a fluorescent lamp because of its vulnerability?
But the stroboscope light is a LED..isn t it?

P.S. sorry but i can t give you any advance on the 45 rpm tip..

[Phonics]

no the strobascope is not an LED it is fluorescent

here

" Many Hi End turntables today still use hysteresis synchronous motors which rely on the line frequency to achieve accurate rotation. Using a conventional strobe to measure these turntables reveals a flaw: If the line frequency is low, the turntable will run slow, but so will the fluorescent light used to illuminate the strobe disc. Result: the strobe may show the correct speed, even though it is wrong! There is a definite need for an independent quartz crystal controlled illuminator. "

www.kabusa.com/strobe.htm

i think that this

"The LED illumination is not syncronized with fluorescent lamps." is just saying that the LED do not use the quartz circuit

[manuele]

OK, they want just tell you not to replace the fluorescent lamp with an LED wich would be instable because non syncronized...

thanks a lot Phonics_

[Revolution]

Here are a few thoughts on the subject

note: I am only referring to the Technics SL1200MK2 , M3D, MK5

#1 Do you mean PLL (Phase Loop Locked) ? The motor is a brushless DC Direct Drive FG (frequency Generator) motor.

#2 The platter is controlled by the pitch control at all times, EXCEPT when the green "Quartz Lock" LED is illuminated. At this point the motor is controlled by the reference vibrations of the x201(4.134 MHz) Quartz Crystal occilator

#3 the Strobe (on the Technics Sl1200) is controlled by an LED driver Diode and it is DC (direct current)...line voltages are always in AC (alternating current) as Westinghouse and Edison fought that battle , AC vs. DC, back in the late 1800's. The line transformer and rectifier are used to convert AC to DC for all turntable functions.

The Technics 1200 turntable uses LEDs (light emmiting diodes) which strobe to pick up the corresponding pitch dots located on the platter side. It DOES Not use a floresent lights in any way.
thanks

keep the tech ?'s coming up

like a flower

revolution

[manuele]

hi Revolution
thanks for your feedback, but some doubts still remain:

-yeah, i mean pll (sorry)..it s the type of circuit included in the sl 1200??

-now i know that the stroboscope light is an LED but what the Service Manual mean when say: "..the LED illumination is not Syncronized with fluorescent lamp.." that replacing it with fluorescent lamp is wrong or what??!?

-on stroboscope tips i like to ask you about those 20 years old abused 1200 that even with the pitch slider set on position 0 (Quartz lock) seems uncalibrated ( the bigger dots on the platter still floats) and it make you want to move the pitch fader to calibrate the right platter speed until stroboscope looks ok (pratically employng the pitch variable resistor for setting the Quartz lock !?!?!). Is this due to the Quartz Oscillator age, or is the LED stroboscope losting syncronization (original frequency) with the Oscillator?

- on your reply you meant the pitch isn t controlled by the Quartz Oscillator.. But why the Service Manual claims : "...with the sl1200mk2 howerever pitch is variable continuosly (analogically) by up to */- 8 % under total quartz-locked control..." ? i'm a little bit confused on this.

Thanks in advance for your patience

bye

[Revolution]

hmmm

on this point - "..the LED illumination is not Syncronized with fluorescent lamp.." that replacing it with fluorescent lamp is wrong or what?

I m not sure but i guess from you other question........

"on stroboscope tips i like to ask you about those 20 years old abused 1200 that even with the pitch slider set on position 0 (Quartz lock) seems uncalibrated ( the bigger dots on the platter still floats) and it make you want to move the pitch fader to calibrate the right platter "

I bet your Quartz Crystal is bad.......I have seen this before and either replaced the Quartz Crystal, or just defeated the Quartz Lock alltogether and then reset the zero point and then the larger pitch dots were still at zero once again!

OK well the SL-1200 is ONLY Quartz Locked at zero and no place else along the +8% thru -8%...it would defeat the idea of a continuous variable resistor (pitch control) and would also require an untold number of crystals to preceisly simulate Quartz Locked Pitch along the entire scale


hope this helps
thanks

revolution

[manu]

yeah, yeah...it definately makes more sense. Entire pitch scale controlled by the Quartz Oscillator would mean max precision movement = all the turntable must look the same, when set on a the same point of the scale (i.e. +4).
But as we know, is the exact opposite: every tt have a quiet unique speed reference when the pitch function comes into play..

So Technics claims like "...the pitch +/- 8% scale is totally under stable Quartz frequncy control.." or "...the strobe light is directly controlled by the Oscillator.." are pretty much bullnuts__

thanks once again Revolution,
your help is much appreciated