What's function of Pitch Adj in Technics SL1210 - MK5?

[Thad E Ginathom]

Thats interesting Thad, did not think the frequency from the incandescent bulb mattered. How about LED? IIRC, member quad has replaced his Dual's stroboscope with a LED.

I'm not good on lighting technical knowledge. Does an LED pulse with the AC supply? If it does, and the markings are spaced to look still at 50 Hz, then it won't matter that it is an LED. If it doesn't pulse at all, then the marks will never look still!

These charts have been around for decades. (err, deck-aids? Never could resist a really bad joke!). Often they have two sides, because UK/Europe AC mains is 50Hz, USA AC mains is something else. All that is necessary is to view them under mains AC electric light! Going back a few of those deckaids, "posher" decks had the marks on the edge of the platter and the built-in light source.

 

[quad]

I'm not good on lighting technical knowledge. Does an LED pulse with the AC supply? If it does, and the markings are spaced to look still at 50 Hz, then it won't matter that it is an LED. If it doesn't pulse at all, then the marks will never look still!

Strobes typically used a neon bulb running off the AC.

Normally, LEDs will run off a DC supply, so they will not "strobe".
However, an LED can be used as a strobe lamp, if it is driven by an AC
signal (or a half-wave rectified one), so it will
pulse at that frequency.
To get sharp light pulses, the circuit uses a zener diode.

Alternatively, the LED strobe can use a quartz crystal driven oscillator to get
an accurate 50 or 60hz strobe. The circuits for both have been posted
on vinylengine and audiokarma, among other places.

Tanoj et al, not all turntables have strobe marking on them. The strobe sheet and external strobe
is needed in that case.

 

[Thad E Ginathom]

Appropriate and sufficient technology: light bulb

Of course, I don't suppose that our power supply is exactly 50Hz, but average? No idea how to approach, let alone do the maths on what difference a given variation would make to pitch.

If one was going to go beyond the humble (and cheap) lightbulb, and go for circuit-controlled clocking, wouldn't it be better to use a higher frequency, with markings designed accordingly?

... To get sharp light pulses, the circuit uses a zener diode.

My theory: If the pulsing is not sharp, the perceived pattern may have unclear edges --- but the essential test is if those dots stand still, not whether or not they are sharp. This is an easy thing to observe.

Reactions from the mathematicians please?

 

[quad]

If one was going to go beyond the humble (and cheap) lightbulb, and go for circuit-controlled clocking, wouldn't it be better to use a higher frequency, with markings designed accordingly?
My theory: If the pulsing is not sharp, the perceived pattern may have unclear edges --- but the essential test is if those dots stand still, not whether or not they are sharp. This is an easy thing to observe.

Yes, as we discussed in an earlier thread, the incandescent lamp will not have
sharp on-off periods, but it will flicker at the AC freq.

You can use any convenient frequency, as long as you can print a strobe
disc with fine enough markings. The postscript program in the link below
can be modified to generate the appropriate markings on the disc

Re: Strobe circle

 

[manua]

Hi,

When I put on the reset button the middle BIG DOTS (2nd from the bottom)still moves slowly in a clockwise direction.So that means at ZERO (after pressing the reset button) still the platter isn't moving in the correct speed.So do I manualy adjust then to make the broad bigger dots go still?

Please revert.

Hello Friends

IMO there is no need of any outside strobe sheet to be downloaded

the platter is already with the markings with the one which has on the strobe

the red florescent light is already there to the left of the platter to a small knob

the light falls on the platter and once the platter is rotaing, all you need to check is that the broad dotts reamain still , there are two kids of dotts,

one is for the 33 rpm and other one is for 45 rpm, the are just one above other

check the picture

Redirect Notice

 

[manua]

Please help on my last query.

 

[santhosh]

Hi,

When I put on the reset button the middle BIG DOTS (2nd from the bottom)still moves slowly in a clockwise direction.So that means at ZERO (after pressing the reset button) still the platter isn't moving in the correct speed.So do I manualy adjust then to make the broad bigger dots go still?

Please revert.

Manua,
If I were you, I would not bother about the position of the button. Correct speed is more important for enjoying your music than what position the button is, so go ahead and adjust it till the dots go still. If the button always had to be at the centre, then it would not be adjustable.

I see you have mentioned big dots....Ideally one set of dots would be for 45RPM and the other for 33 1/3. Since I don't have a Technics TT, am not sure about which ones are which. If big dots are for 45RPM, then the big dots should go still. Your manual, dealer or Google baba should help.

 

[Hiten]

Please help on my last query.

Manua,
I downloaded your TT manual and what I understand is for normal listening only big dots matters so...
1) slide the pitch adjustment knob to zero mark.
2) Press reset button (This will be pre set default speed of the turntable)
3) Adjust the pitch slider so as big dots appear stable.
That's it.
The rest of the strobe dots are for matching purpose for DJs to match speed while mixing two records.
Regards

 

[Tanoj]

Hi Manu,

Sorry for replying so late, however what Hiten said is absolutely correct, follow his instructions

Cheers

Tanoj

Friends, whatever i say is just from my point of view and is an output of my research, not necessary to be correct, and i do not want to be offencieve to anyone

i really like you all and really enjoy sharing and recieving messaged from you.