hi,
just got back to this repair after a spell in hospital, this is a circular display consisting of 7 seperate red, blue and green led arrays, the centre array was not lighting most of the blue and green leds,
as the unit was oldish and the centre array does more work than the others.i put this down to age,
so i labouriously replaced all the green and blue leds, and they all lit.and then watched in horror as they all failed one by one, or should i say three by three, as they are in chains of three.
each chain is fed by a 13.8 volt supply through a 91 ohm resistor, now on all the other arrays this results in 9.5 volts at the leds, which of course is fine,
but on the faulty centre array its reading 13.14volts to each chain of three, hence the demise of said leds.
led spec 5mm
3.2v – 3.8v
465nm
9000mcd
for some reason, the new leds are not allowing the 91 ohm resistors to do their job?.
please help
doug
just got back to this repair after a spell in hospital, this is a circular display consisting of 7 seperate red, blue and green led arrays, the centre array was not lighting most of the blue and green leds,
as the unit was oldish and the centre array does more work than the others.i put this down to age,
so i labouriously replaced all the green and blue leds, and they all lit.and then watched in horror as they all failed one by one, or should i say three by three, as they are in chains of three.
each chain is fed by a 13.8 volt supply through a 91 ohm resistor, now on all the other arrays this results in 9.5 volts at the leds, which of course is fine,
but on the faulty centre array its reading 13.14volts to each chain of three, hence the demise of said leds.
led spec 5mm
3.2v – 3.8v
465nm
9000mcd
for some reason, the new leds are not allowing the 91 ohm resistors to do their job?.
please help
doug
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