"RJH" wrote in message
...

"Woody" wrote in message
...

"RJH" wrote in message
...
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.

**The power lamp is probably run from the AC supply. You'll need to switch
your meter to 'AC' to measure anything. Also, be aware that the lamp in the
'STEREO' indicator may be of a different type and rating.


I clearly have no idea what I'm doing here so any further guidance
appreciated!

**Buy a 12 Volt lamp of the correct size and you'll be close to correct.
Alternatively, the replacement with an LED will also work. The only drawback
with using an LED is related to the radiation angle of the LED. Not all the
lettters (assuming the word 'STEREO' is illuminated when the unit is in
stereo) will be uniformly illuminated. I prefer to use Lumileds (much more
difficult to buy) for this purpose. They have a very wide radiation angle
(around 120o) and can cope with far higher currents.


--
Trevor Wilson
www.rageaudio.com.au