HindlePower AT30 SERIES Operating And Service Instructions page 58

SERVICING THE AT30
PROBABLE
SYMPTOM
CAUSE
Front panel is 1. Control pc
dead, but ac boards
& dc voltages (A1/A15) not
are present at connected
TB1(+/-)
2. Defective
Main Control
PC Board (A1)
3. Defective
wiring
Front panel 1. Defective
dies during ac Power Supply
power failure, Ballast Resistor
but dc voltage (R3)
is present at
TB1(+/-)
2. Defective
wiring
AT30 output 1. Defective
voltage too SCR
high, or not
controllable
2. R4 or R14 is
defective, or
wrong value
3. Defective
temperature
compensation
probe (optional)
4. Defective
Main Control
PC Board (A1)
52
RECOMMENDED ACTION
1. Confirm the Gate Driver PC B oard (A15-P17) is firmly
connected to the Main Control PC Board (A1-J17). Confirm
the two (2) signal harness plugs are firmly inserted into the
connectors (J25 and J26).
Gate Driver PC Board
2. If the green AC ON indicator is lit, but the rest of the front
panel display is dead, replace the Main Control PC Board
(A1).
3. Check the two (2) harness wirings to the Gate Driver PC
oard connectors (A15-J25 & A15-J26), for signs of insulation
B
damage, burns, etc. Confirm all wires are securely crimped in
the connector.
1. Use a dc voltmeter to measure voltage from TB1(-) to J1 pin
# 8 on the Main Control PC Board (A1). It is normally 12 Vdc
when the rated dc output voltage is present at TB1(+/-).
If it is not 12 Vdc, remove all power from the AT30, and
measure the resistance of R3, from TB1(+) to J1 pin # 8. See
the table in Section 3.6 for the proper resistance value. If the
resistance is not within 10% of the table value, replace R3.
2. Remove the safety shield. Check the wiring to and from
TB1 and the Main Control PC Board (A1) for signs of
insulation damage or burns. Repair any damaged wiring.
1. Disconnect the wire harness plug from connector J26 on the
top of the Gate Driver PC Board (A15). Restart the AT30. If
you are able to measure dc output current, one of the SCRs is
defective. Replace rectifier modules (A16x) as needed.
2. On the back of the front panel, locate R4 and R14 on the
Gate Driver PC Board (A15). Remove one end of each
resistor and measure its value with an Ohmmeter. Refer to
the table in Section 3.6 for values. If either resistor is not
within 1% of the specified value, replace the scaling resistors
(R4 and/or R14) as needed.
3. Remove the leads from the probe and measure its
resistance. At 77 °F / 25 °C the resistance should be about
Ω
10,000 . If it is not, replace the probe assembly (A10).
4. If the front panel meter displays more than 110% of the
AT30 rated dc current current, the Main Control PC Board (A1)
may be defective. Unplug the system harness connectors
(J25 & J26) from the Gate Driver PC Board (A15). If the
output current drops to zero (Adc), replace the Main Control
PC Board (A1).