front panel LED help sought
robert.jarratt at ntlworld.com
Wed Jan 14 16:25:34 CST 2015
> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of tony
> Sent: 14 January 2015 21:50
> To: General Discussion: On-Topic and Off-Topic Posts
> Subject: RE: front panel LED help sought
> > Without schematics, can anyone suggest how I might go about
> > determining a suitable replacement LED from an electrical perspective?
> Or, if you can find even one working LED on the original panel, remove it
> connected it (correct way round) with a 330 Ohm or 470 Ohm (or so)
> series to an adjustable bench supply. Turn up the supply until the LED is
> at what you consider to be normal brightness (this will be 5-10V I would
> Now measure the voltage across the LED itself and the current through it
> deduce the latter from the voltage across the series resistor and the
> value of that resistor). Try to find an LED that matches those values for
> voltage and operating current.
> Or as I said, just stick in standard red LEDs. I've replaced LEDs many
> without thinking what I am fitting.
"without thinking" is that an impostor pretending to be Tony? :-) :-)
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