On Mar 1, 5:23*pm, D Yuniskis wrote:
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.)

Yikes! *You should be looking at more like 1mA through the lamp.
Are you sure about the connections in the circuit?



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- Hide quoted text -

- Show quoted text -

Well I can see that the big (3 to 5 watt) resistor feds the neon
lamp. I don't know what else the circuit does.... I didn't bother to
try and trace the whole thing out. Perhaps I can look at it more
closely tonight and see if I can make something more out of it.

Thanks,

George H.