8
6.
Check CPU board
A.
Disconnect temperature probe connector from J302 on
CPU board.
B.
Turn power on.
C.
Verify that potential across pins 1 & 3 of J302 reads 5 volts
with a voltmeter. If voltmeter does not read 5 volts, replace
CPU board.
9.04 Unstable temperature
control
1.
Use gable cover provided to improve temperature control.
2.
Verify that temperature setpoint is set at desired value.
3.
If control is stable, but not at desired temperature, check
temperature calibration. Readjust if necessary.
4.
Check temperature probe (See Paragraph 9.03, Step 3).
5.
Check CPU board (See Paragraph 9.03, Step 6).
9.05 Too much heat.
1.
Check temperature probe (see Paragraph 9.03, Step 3).
2.
Check TRIAC (See Paragraph 9.03, step 5).
3.
Check CPU Board (See Paragraph 9.03, Step 6).
5.
Check TRIAC (Q2 on power supply board)
A.
Turn power on.
B.
Let bath stabilize to desired setpoint value.
C.
Place an AC voltmeter between pins 1 & 5 on wire side of
connector J105 on power supply board. Voltmeter should
fluctuate between 0 volts and anything less than 5 volts.
D.
If voltmeter does not show specified values in Step C,
replace power supply board.
9.03 No Heat
4.
Check Heater
(Cont'd)
A.
Disconnect unit from electrical supply.
B.
Disconnect heater from circuit and check resistance
between heater leads (red and white wires) with an
ohmmeter. Approximate heater resistance values are
shown below.
120V
230V
24 ohms
47 ohms
If resistance reads 0 or infinite, replace heater.
C.
Check resistance between heater leads and ground (green
wire). If resistance reads 0 ohms, replace heater.
D.
Check resistance between heater leads and outside case of
heater. If resistance reads less than 250K, replace heater.
