Technics SL-1200 Stylus Illuminator LED

[Phildefer]

I own a couple SL-1200MK2's for which I want to replace the incandescent stylus illuminator bulb with LEDs. I was able figuring out the circuitry from the SL-1200MK5 service manual. However the OEM blue LED (RXQ1012) is over $15 which defeats the purpose of replacing the light bulb in the first place. Therefore I was looking for a cheaper equivalent LED but could not figure the voltage and current. Does anyone have the specs of the blue LED?

[herlsy]

Just go to radioshack and get a 5mm LED, it will have the specs on the package so you can choose the right resistor.

I read somewhere that the voltage coming off of the main board to the pop-up is 20v, but after testing myself, i got 21.5v.

[Phildefer]

Just go to radioshack and get a 5mm LED, it will have the specs on the package so you can choose the right resistor.

I read somewhere that the voltage coming off of the main board to the pop-up is 20v, but after testing myself, i got 21.5v.

Thanks for the response. However I am not sure that will work as the circuit of the MK5 is a little more complex than the previous models; it has a Zener diode mounted in reverse-parallel with the LED (the anode of LED connected with cathode of Zener, and vice-versa), assuming the Zener's purpose is regulating the voltage. There is also a couple of half-watt 2.2k resistors mounted in parallel (I would assume the aim is getting 1.1k, 1watt). I have seen posts and videos about replacing the lamp with a LED and it doesn't look like it's just a matter of placing a resistor in series with the LED, which is the reason why I am looking for the OEM LED specs; I don't want to blow the main circuit board...

[herlsy]

I guess i misread, i thought you were putting LEDs in the mk2?

I think if you know your voltage coming off the mainboard, and are savvy with electronics, a voltage regulator and resistor could be done with just about any LED.

Are you looking for the specs just to get the right brightness or what?

[Liambo]

If you have mk2's i would advise you to buy two 3mm LED's bend them at a 90 degree angle so the brightness shines onto the record and the resister should be averagely 1k ohm or 1.25k ohm..

Hope this helps. As i have just done it to mines.

[Phildefer]

I guess i misread, i thought you were putting LEDs in the mk2?

I think if you know your voltage coming off the mainboard, and are savvy with electronics, a voltage regulator and resistor could be done with just about any LED.

Are you looking for the specs just to get the right brightness or what?

You read right; I do want to replace the bulb of my MK2 by an LED. I just wanted to use the Mk5 design to make sure I don't blow up the main board. The Mk2 and Mk5 roughly have the same voltage (20-22volts). Like I said I am looking for voltage and max current so I can find a similar LED...

[Phildefer]

If you have mk2's i would advise you to buy two 3mm LED's bend them at a 90 degree angle so the brightness shines onto the record and the resister should be averagely 1k ohm or 1.25k ohm..

Hope this helps. As i have just done it to mines.

You just put the resistor in series with the LED? Did you leave the original 1.5k resistor which is soldered on 2 poles of the switch?
Are yours MK2's?

[Liambo]

You just put the resistor in series with the LED? Did you leave the original 1.5k resistor which is soldered on 2 poles of the switch?
Are yours MK2's?

Yes mines are mk2's, and i replaced the resistor with a 1k ohm resistor and replaced the original lamp with a 3mm LED (3V) and bent it 90 degrees. Haven't got any pictures yet as i haven't assembled it all back together properly as i'm now working on the pitch fader and 33/45..

Oh and i'm an electronics engineer by day.

[Phildefer]

Yes mines are mk2's, and i replaced the resistor with a 1k ohm resistor and replaced the original lamp with a 3mm LED (3V) and bent it 90 degrees. Haven't got any pictures yet as i haven't assembled it all back together properly as i'm now working on the pitch fader and 33/45..

Oh and i'm an electronics engineer by day.

Thanks for the feedback. However looking in the Mk2 service manual I see that the 1.5k resistor is mounted in parallel with the switch. So when the switch is at the closed (on) position it short-circuits the resistor. Hence if I just replace the lamp by the LED it will not be protected which I believe would blow the LED and damage the main board... Am I missing something?

[Liambo]

Thanks for the feedback. However looking in the Mk2 service manual I see that the 1.5k resistor is mounted in parallel with the switch. So when the switch is at the closed (on) position it short-circuits the resistor. Hence if I just replace the lamp by the LED it will not be protected which I believe would blow the LED and damage the main board... Am I missing something?

Sorry you are correct on saying that, if you don't have a resistor that is parallel with the LED or none at all and you try to switch it on you will just blow out the LED