LumaSense Technologies M390 - Manual (Page 25)

M390 Manual Troubleshooting 25
6 Troubleshooting
Symptom Tests/ Solutions
1. Blackbody Does not heat up Is there both Argon purge gas and cooling
water flowing?
Are both low flow alarms off?
2. Blackbody Does not heat up-flow alarms
are off Put the controller in MANUAL mode. Set to
approximately 20% power. Do you hear SCR
buzzing?
Yes: Wait until the controller reads
temperature above the beginning of the
temperature range. (either 250 C or 600 C)
Go to steps 3 to 7.
No: Check Low Flow alarms are working by
turning off cooling water supply for a few
seconds. Alarm should sound. Repeat with
Argon purge. Alarm should sound. Go to
step 7.
3. Answer to (2) is Yes: Blackbody Does not
heat up-flow alarms are off. Alarms test OK. Check the over temperature thermal cut-out
switch located on the reflector plate just
under the blackbody cavity. This is a white
(ceramic) disc with a manual reset push
button. Push this button in if it has tripped.
This opens the 4-20 ma control signal to the
SCR.
4. Blackbody Does not heat up-flow alarms
are off. Alarms test OK. Over temp switch
OK.
Cavity may be open or damaged. Apply
more power in Manual mode. Set power to
about 40%. Look inside the cavity opening
for signs of local heating in unsymmetrical
patterns.
5. (4) above showed no signs of
unsymmetrical heating patterns and there is
no glowing anywhere in the cavity.
With power set at about 30% in Manual
mode, measure AC volts across the two
cavity electrodes.
If Velectrodes >2 VAC, cavity not connected
at one or both electrode seats.
6. If V electrodes = 0 VAC Check SCR main fuse. Check 4-20 ma
connector to SCR. Check 4-20 ma signal to
SCR from temperature controller.
7. If V electrodes > 0 VAC. Still do not
observe any glowing on cavity.
Cavity must be open. Shut system down and
replace cavity.
8. Blackbody heats up, but does not control
temperature. Check that controller has been set to AUTO
mode after the blackbody temperature >
beginning of temperature range.