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  » Forum » Turntables (english only - please!) » 12x0 - Helpdesk » LEDs and resistors

LEDs and resistors
yashi
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Posts: 7
# 29.12.2016 - 20:57:29
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Hello, i hope not to start above discussed thread.

i'd like to change leds on my 1200s but i don't wanna destroy them...only LED, no needle/target light.

For example, in pitch-33/45 and strobo all with blue 3.3v led, they need resistors or not? If yes, where i put them, on mainboard or in a cable?
kaype
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Posts: 4459
# 29.12.2016 - 21:12:41
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they are all 3.3V LEDs, no need for a resistor.

Strobe - 4x 5mm LED
33/45 - 2x 3mm LED
Pitch - 1x 2x5mm LED

greetings, Fabian
yashi
Einmalposter
Posts: 7
# 30.12.2016 - 17:11:27
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thanks kaype.

now, another "scenario": i'd like to use yellow 2.2v led.
Where i put the resitors?
kaype
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# 31.12.2016 - 12:00:36
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somewhere before or behind the LED, doesent matter.

sorry, but ... if you ask where to put a resistor i highly recommend to let someone do this job for your obviously you dont have any clue about electronics.

???

greetings, Fabian
yashi
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Posts: 7
# 05.01.2017 - 00:58:42
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ok Fabian...sorry for my dumb question, i started from the beginning with different approach.
First, i've printed service manual and schematic diagram of MK2, then with multimeter i've start to testing various voltages.

These the results:

-Voltage on strobo (brown/red cables): 13,02v

-Leds 33/45: 2,37v

-Led pitch: 2,07v

-Needle (original lamp): 19,53v

-A/C on mainboard (yellow-blue): 28,2v

First of all, are these voltage correct? Seems to me that the voltage on 33/45 and pitch are low...

Thanks in advance :)


Zuletzt modifiziert von yashi am 05.01.2017 - 00:59:06
kaype
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Posts: 4459
# 05.01.2017 - 10:09:26
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never tested them while LEDs are installed and as these LED Voltage are generated with resistors it also depends on how much resistance your multimeter has, this can affect the voltage. i would say to stick to the diagrams, these say 3.3V if i am not wrong.

other voltages look fine.

greetings, Fabian
yashi
Einmalposter
Posts: 7
# 10.01.2017 - 19:31:39
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I've tested another MK2, 1210 build in 1995. (previous was 1200 of 1984).

Voltage are basically the same but i cannot understand the LED/voltage step.

For example, about pitch led; you tell me to use a 3,3v LED...found 2,1v on + and -

With this low voltage, how can light up the led? :eek:
kaype
König

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Posts: 4459
# 11.01.2017 - 09:49:55
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as i said, the voltage are not generated by transistors, they used exact resistors for the current the LED uses. As you hock up your multimeter, and the multimeter has also current consumption by default, the voltage changes of course.

???

Basics in electronics. :yes:
yashi
Einmalposter
Posts: 7
# 20.02.2017 - 13:11:03
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Hello, this is the result







1200Mk2 built in 1984, completely disassembled, washed and re-greased.

I put resistor on all LEDs, don't like too much brightness...