On Mar 1, 7:32*pm, John Larkin
wrote:
On Mon, 1 Mar 2010 13:53:13 -0800 (PST), George Herold





wrote:
I've got a tankless electric water heater from eemax. that stopped
working the other day. *eemax won't provide any component level
support, but I've ordered a new board for $45.00.

When I opened up the unit, after switching off the circuit breaker on
the 240V AC line, I observed that a big (maybe 3-5 watt) (metal film?)
resistor was discolored and was an open circuit. *The markings look
like 100 ohms, but because of the discoloration it's hard to be sure.
I say metal film because the resistor is pale blue in color. *The
resistor feds a neon indicator bulb... (And probablly more of the
circuitry.)

My question. *Is 100 ohms a good value as a current limiting resistor
for a small neon lamp running off 240 V AC? *(60 Hz if that matters.)
I'm not sure what the I-V curve for the lamp will look like. *(Is the
one shown here OK?)

http://en.wikipedia.org/wiki/Neon_lamp

Thanks for any advice.

George H.

Numbers more like 330K to 560K are more reasonable. Higher currents
will sputter the gas and make the thing fail sooner.

Better yet, use an LED.

John- Hide quoted text -

- Show quoted text -

Well somehow this must also feed power to some other part of the
circuit. There's also an LM324 and small triac Q601e3 on the pcb.

George H.