Dead heating element.
Dead heating element.
(OP)
I have a 36 VDC heated stage that is dead. The input power checks OK, but the heating element itself shows dead short, 0 ohms resistance. An open circuit I could understand, but not a dead short. The leads & connections look OK, no obvious damage. What's going on here?
RAYBAND
Rock Island Arsenal
AMSTA-RIA-SEM





RE: Dead heating element.
A heating element with 1000 W would have 0.77 ohms when hot and around 0.6 ohms when cold.
So, is it really a dead short or just close to zero?
Gunnar Englund
www.gke.org
RE: Dead heating element.
TTFN
RE: Dead heating element.
Part of a microscope? If so then it wouldn't be 1000 watts.
As far as how it could be shorted? There's always a rational explanation but it might be difficult to determine via the Internet.
RE: Dead heating element.
Actually the other day I came across a heated stage accessory for a microscope that would heat samples up to 1500C (yes C)to study phase transitions and crystal structure changes. That probably consumes 100's of W to kW, I wish I could find the link again because it caught my eye- learn something new everyday.
rayband:
Have you checked if the any connections or the element is shorted to ground and thus possibly shunting power away from the element?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"It's the questions that drive us"
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
RE: Dead heating element.
rayband; More info? Microscope stage? Do you know what wattage your stage is supposed to be?
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Dead heating element.
There are DVOMs around that use "0" to indicate Open Circuit and 0.0 to indicate zero ohms. Ya never know.
RE: Dead heating element.
This is an old unit we (metallurgical engineers, not EE's) are trying to rebuild. It works by 'printing' a layer of plastic (sort of like hot melt glue) in the x-y plane, then indexing up the z plane and repeating until a solid model has been 'printed'. The heated platen's purpose is simply to keep the model under 'construction' stuck to the platen during the process.
Again, thanks to all.
Ray A.
RAYBAND
Rock Island Arsenal
AMSTA-RIA-SEM
RE: Dead heating element.
R = V*V/P
R = 36*36/250
Hence R = 5.18 ohms
Your meter should be able to differentiate that over shorting the probes together.
You have an open heater element.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Dead heating element.
TTFN
RE: Dead heating element.
This assumes that the leads are normal wire. Safe bet that the heater element is something like nichrome or similar.
In other words, perhaps the element itself is fine. If you can get inside then it might be easy to repair.
Maybe...
Maybe not...
RE: Dead heating element.
unless im not understanding this correctly...
RE: Dead heating element.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Dead heating element.
RAYBAND
Rock Island Arsenal
AMSTA-RIA-SEM
RE: Dead heating element.
Perhaps the little device is a thermal overload ('too hot') protection device ? If it is in series and open circuit (the device), then perhaps you've found the problem.
RE: Dead heating element.
TTFN
RE: Dead heating element.
RAYBAND
Rock Island Arsenal
AMSTA-RIA-SEM
RE: Dead heating element.
RE: Dead heating element.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Dead heating element.
You just can't beat going down to Radio Shack and getting a part. I designed a jet engine test cell for the Air Force that was PC based. They had tried forcing me to use some old Data Generalmicro. Later in an AF presentation they called it Radio Shack Compatability. I saved that page! I also tried to save thm $51K, that got me in so much trouble. You choose your battles with the military very carefully.
RE: Dead heating element.
I solder them into one of my products. Take too long or forget the multiple heat sinks... and the part works. :(
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com