(George) writes:

Hi Sam...thanks for the response.

Did you disconnect at least one end of the resistor? It might be open
and you're the resistance of other parts in the circuit.

I completely yanked it and get this 2.5K reading. It is very clearly
labeled on the resistor as 1.8K Ohm 5W...it's a good sized ceramic
thing.

Assuming the resistor itself is marked 1.8K, then it's likely changed
value due to overheating or some other cause. Have you checked the
zener and any other parts it's feeding?

This power resistor is fed from a diode giving a half-wave rectified
120V voltage into one side of it...and on the other it connects into a
zener and then a a 680 ohm 1/4W resistor....those check out fine with
a reasonable resistance.

I think i'll source to try and source one of these 1.7K 5W
resistors...can't cost that much. Maybe it's dropping too much
voltage? I don't have a schematic or a part number for the zener to
really tell.

It's certainly worth trying, easy and cheap enough.

What else is it feeding?

--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
+Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm
| Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html

Note: These links are hopefully temporary until we can sort out the excessive
traffic on Repairfaq.org.

Important: Anything sent to the email address in the message header is ignored.
To contact me, please use the feedback form on the S.E.R FAQ Web sites.