"RJH" wrote in message
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"Woody" wrote in message
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"RJH" wrote in message
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Hi - can anyone identify this bulb:
http://tinyurl.com/3cf2h
from a Pioneer SX 750 receiver, late 70s model? It's about 3mm in
diameter
and is used on the panel to indicate 'stereo'. And where to find a
replacement?
Many thanks
Rob
Check the polarity and voltage of the supply and replace it with a LED.
The
negative side of the supply goes to the LED leg that has a small flat on
the
LED body next to it.
You should have no difficulty in finding a suitably sized LED, but it
will
need a current-limiting resistor in series. Take the supply voltage,
deduct
2 and divide by 10. This will give the value of resistor in K-ohms
needed.
E.g. suppose the supply is 12V, 12-2=10/10=1K. That will runs 10mA
through
the LED which will be more than enough. If it is too bright try
increasing
the resistor value by factors of 2 each time. The resistor will need to
have
a power rating of 0.25W or higher. The resistor can go in either leg.
--
Woody
Many thanks for that Woody - I will give it a go. But, I can't figure out
what the voltage is!
I attached a voltmeter to the 2 wires coming out of one the lamps that
work
('Power') and couldn't get it to measure much - it was switched on, the
voltmeter read a battery correctly, but no DC current on the bulb supply
except an occasional 0.3v - not steady though.
I clearly have no idea what I'm doing here so any further guidance
appreciated!
Rob
Just put your meter on volts across one of the bulbs. It is possible that
the power bulb is fed from a.c. hence why you get no reading. You can put a
stereo signal in off air and look across the dead bulb contacts - there may
be a small resistor in series but it won't matter. (Under-run a bulb by 10%
and you get 10x the life!) Don't try reading current - it is of no
consequence.
You can by the way buy those bulbs from spares outlets - they are known as
'pea' bulbs and are usually 6V or 12V. Again the supply volts should give an
indication, but if all else fails buy one of each and try the 12V first.
--
Woody