REGULATOR GP 3827844 - Caterpillar

Checking Transformer NT3
Ensure that the transfer switch is set for NORMAL automatic operation.
Check for 12 ACV across the yellow leads on terminals 4 and 5 on the logic package.Expected Result: The voltage is present.Results:
YES - The voltage is present. Go to 3.
NO - The voltage is not present. Transformer NT3 has failed. After checking transformers NT4 and ET2, proceed to ""Replacing Transformer(s)"".
Checking Transformer NT4
Ensure that the transfer switch is set for NORMAL automatic operation.
Check for 12 ACV across the yellow leads on terminals 6 and 7 on the logic package.Expected Result: The voltage is present.Results:
YES - The voltage is present. Go to 4.
NO - The voltage is not present. Transformer NT4 has failed. After checking transformer ET2, proceed to ""Replacing Transformer(s)"".
Checking Transformer ET2
Ensure that the transfer switch is set for NORMAL automatic operation.
Check for 24 ACV across terminals 8 and 9 on the logic package. Check for 12 ACV across terminals 8 and 10 on the logic package. Check for 12 ACV across terminals 9 and 10 on the logic package.Expected Result: The voltages are present.Results:
YES - The voltages are present. Therefore, the fault may be intermittent. Check all the electrical connections. If the problem still exists, repeat the entire procedure.
NO - Any of these voltages are not present. Transformer ET2 has failed. Go to ""Replacing Transformer(s)"".Replacing Transformer(s)
Disconnect all power to the automatic transfer switch by locking open the upstream switching devices on both the normal feeder conductors and emergency feeder conductors. The upstream switching device can be a circuit breaker.
Remove the voltage selector connector from the transformer panel by depressing the tabs on the side of the connector and pulling away from the transformer panel. See Illustration 2.
Illustration 2 g00677356
Removing the voltage selector connector
Remove the transformer panel from the baseplate by removing the four screws which are located on the sides of the baseplate. See Illustration 3. After removing the last screw, gently tilt the top of the transformer panel forward until all transformers are visible. If wiring is long enough, support the transformer panel on top of logic modules. See Illustration 4. If wiring is not long enough, use some type of spacer between logic modules and the transformer panel. Do NOT support the transformer panel by the wiring.
Illustration 3 g00677357
Removing transformer panel
Illustration 4 g00677358
Transformers of the automatic control switch
Locate the faulty transformer(s). Remove the faulty transformer(s) from the assembly. It will be necessary to drill out two pop rivets each in order to remove the transformers. See Illustration 5.
Illustration 5 g00677360
Removing a faulty transformer
Disconnect the transformer connections. Those that terminate in a nylon connector may be removed by using a very small screwdriver or probe to compress the "barbs" on the terminal pin inside the connector. See Illustration 6. Alternatively, the AMP extraction tool may be used, by pressing the tool onto the pin until it "bottoms". See Illustration 7. The pins should be carefully removed. Replace the transformer. Fasten the transformer using the included self-tapping screws. Install the screws through the transformer panel into the transformer base.
Illustration 6 g00682989
Disconnecting