La Marche A36D, Инструкция по эксплуатации

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MODEL A36D SERIES - INSTRUCTIONS AND TROUBLESHOOTING
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12.3.5 Ground and short circuit test.
A simple ohmmeter check can be performed to check the unit for a short to ground, primary to secondary
breakdown, AC- DC short, or DC ground. Before installation of a new unit, the above checks should be
made before installing. If a short of this type is suspected on a unit in service, check as follows:
1. Disconnect AC input power to the unit. Disconnect the DC battery and loads from the rectifier.
2. Set ohmmeter scale on ohms scale RX100.
3. Measure from one terminal of the input to one terminal of the output. Meter should not indicate.
If the meter reads full scale deflection, this indicates an AC - DC short. During shipping, an AC wire
may rub against the DC lugs, terminals, etc. and cause a short. These problems may be eliminated
by very carefully inspecting the wiring to make certain the AC wires are not touching the DC wiring.
4. Check the input terminals to ground and check the output terminals to 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:
1. On the analog ohmmeter, set the switches on “ohms”, “DC”, and “Rx10,000” scale.
(Refer to Figure 1)
2. 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.
3. 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”, “DC”, and “Rx100” scale. (Refer to Figure 2)
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.