MODEL TPS - INSTRUCTIONS AND TROUBLESHOOTING INFORMATION
18 OF 20
CPN 40615
4.
Check the input terminals to ground and check the output terminals ground. If the
meter indicates full scale deflection, a wire is touching a metal part of the rectifier.
Look for wires that are near any metal part and inspect for possible breakdown
caused by shipping. The heatsink of the diodes and the control unit are insulated
from ground through the mounting legs.
12.4
TROUBLESHOOTING AND REPLACING THE TRIAC
The procedure for checking the triac is as follows:
•
On the analog ohmmeter, set the switches on “ohms”, “d.c.”, and “Rx10,000” scale.
•
Disconnect the triac to be checked. Using an ohmmeter, measure the resistance between main
terminals, MT1 and MT2 in both directions. A good device will indicate open circuit in both
directions, a low resistance indicates a shorted device.
•
Set analog ohmmeter to Rx100 scale.
•
To check for a shorted triac gate lead, measure the resistance between gate (GATE) lead and main
terminal MT1. A reading of zero ohms in both directions indicates a shorted gate. A reading of
infinity in both directions indicates an open gate and the triac should be replaced. A good device
should have resistance in both directions, but not zero ohms.
12.5
TROUBLESHOOTING AND REPLACING POWER SILICON DIODES
/ MODULES
The procedure for checking a silicon diode is as follows:
•
On the analog ohmmeter, set the switches on “ohms”, “d.c.”, and “Rx100” scale.
1.
Isolate one end of the diode by disconnecting the wires attached to the nipple (or pigtail) end of the
diode (only one end of the diode must be disconnected). On a diode module, both of the outside
leads must be disconnected.
2.
Clip one lead of the ohmmeter to the anode lead of the diode. Clip the other ohmmeter lead to the
cathode.
3.
Note the ohmmeter reading. Then reverse the leads to the diode. Again, note the ohmmeter
reading. If the diode is good, the meter will indicate a high resistance in one direction and a low
resistance with the leads reversed. If the diode is shorted, the meter will read full scale, or zero
(“O”) resistance with the leads in either direction. If the diode is “open”, the ohmmeter needle will
not indicate or it will show infinite resistance in either direction, indicating an open circuit.
4.
All diodes must be checked in the event that more than one diode is defective.
5.
If the diode is defective, remove the defective diode from the heatsink and replace with a new
diode.
