SL-1700 mk2 - replacing strobe LEDs

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Hannes_Hannes
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SL-1700 mk2 - replacing strobe LEDs

Post by Hannes_Hannes » 07 Nov 2019 19:52

I would like to replace strobe LEDs with brighter ones, at least some of these. According to service manual there are seven LEDs connected in series along with 120 ohm resistor. Does anybody know what is the source voltage? I assume it's 12 V but not quite sure. As I prefer white LEDs it's obvious I couln't put all seven as they have higher forward voltage than red ones. If I knew the source voltage I could use the same 120 ohm resistor and calculate how much white LEDs I would need and soldering bridging wires in place of old LEDs.

paddypaws
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Re: SL-1700 mk2 - replacing strobe LEDs

Post by paddypaws » 18 Nov 2019 18:28

There is a 20v rail in the turntable but I’m not 100% sure if that is used for the strobe and it will be switched negatively from one of the chips. I think what ever TP5 voltage is is what feeds the LEDs again I think 20v dropped to 18.4 for the LEDs by R212. I would always assume a higher voltage than 14v - 15.4 as 7 red LEDs will normally drop about 2v to 2.2v each It won’t work otherwise.
Please report back when you’ve done it.

paddypaws
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Re: SL-1700 mk2 - replacing strobe LEDs

Post by paddypaws » 18 Nov 2019 21:50

Just to confirm the supply to the LEDs is indeed 20v, I’ve checked the schematic. Please report back once you’ve done the change.

Hannes_Hannes
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Re: SL-1700 mk2 - replacing strobe LEDs

Post by Hannes_Hannes » 24 Nov 2019 15:46

Thanks for your answer. I thought the supply voltage to be 12 volts as it is to the stylus illuminator on the same board. It may take a while however before I could find some time to do the work.

paddypaws
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Re: SL-1700 mk2 - replacing strobe LEDs

Post by paddypaws » 24 Nov 2019 16:26

The 20v is used as 12v isn’t enough to light 7 LEDs in series.

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