KW Checkout
What to Look For When Checking Out A KW Transformer
External Inspection
1. UNPLUG THE POWER CORD FROM THE WALL OUTLET
2. Checkout the Bakelite Case for cracks & broken handles.
3. Turn each of the 6 terminal Lugs until it’s tight. If it turns past tight then the terminal stud needs to be replaced.
4. Carefully check the Power Cord for cracks and or missing bits of Insulation.
5. If the cord is good set both handles to the ZERO position.
6. Plug the Cord into a wall outlet.
7. Does it make a loud Hum? Fix it Here.
8. Connect an AC Voltmeter to terminals A and U.
9. Slowly bring up the A handle while watching the meter. The voltage should start at 4 to 6 volts and rise slowly and steadily up to between 17.5 and 21 volts. The starting and final voltage depends on your home power voltage and varies by neighborhood. If the voltage is not steady or out of range you might have a problem.
10. Test the whistle circuit and compensation winding. With the A handle all the way up watch the AC voltage while slowly pushing the whistle handle to A counter clockwise. The voltage should increase by 5 volts and hold there until you release the whistle handle. If the voltage does not stay steady than the switch needs to be cleaned, adjusted or replaced.
11. Test the direction switch. With the A Handle all the way up watch the AC voltage while pushing the A “Direction” button down. The voltage should drop quickly to near zero volts until you release the direction button. On release the voltage should return to where it was initially. If the voltage does not drop and then return on release than the switch needs to be cleaned, adjusted or replaced.
12. Did the Whistle lever return to the center position when released? If it didn’t return to center then it needs to be cleaned, lubricated, adjusted or replaced.
13. Connect the AC Voltmeter to Terminals B and U and repeat steps 9 and 12 with the B Handle.
14. To test the Circuit Breaker set both A & B handles back to zero
15. Short across the terminals B and U with a screwdriver shaft.
16. Slowly raise the B handle. The Circuit Breaker should trip within a second or so and the red light should come on.
17. Set the B handle back to zero and remove the short. The red light should go out. Replace the Circuit Breaker if it doesn’t trip or it doesn’t reset.
18. UNPLUG THE POWER CORD FROM THE WALL OUTLET
Remove the Cover
1. Verify that the Power Cord is unplugged!
2. Remove the top B handle by grabbing it at the center and pulling straight up while gently rocking side to side.
3. Remove the aluminum disc and the second A handle by lifting straight up.
4. Remove the Whistle handle by grabbing it at the center and pulling straight up while gently rocking side to side.
5. Remove the 4 Phillips Head Screws that hold the KW top cover on.
6. Remove the KW top cover.
Internal Inspection
1. Check that the 4 carbon rollers are in good shape and roll easily. No flat spots or chips. If any are bad or worn out replace them.
2. Check for loose solder joints especially on the larger wires where they connect to the Switch Mechanism sheet metal. If they are loose clean with a Dremel with a wire wheel then re-solder them.
3. Check for loose wires. especially the 4 that attach to the back of the terminals.
4. Check for wires that are burned or where insulation is falling off. Replace the insulation with shrink tube or better yet replace the wire.
5. Check the rectifier discs and their insulation washers. Are they burned, melted or loose? If so replace the disc and washers or replace it all with a new diode.
6. Replace the power cord if it has cracks, is missing insulation or the plug is bad.
7. Clean the whistle switches with CRC QD Contact Cleaner whether they need it or not. Get it at Home Depot in the Electrical section.
8. Check for wires that are burned or where insulation is falling off. Replace the insulation with shrink tube or better yet replace the wire.
9. Check for loose solder joints especially where heavy wire is soldered to the Circuit Breaker.
10. Older style KW Circuit Breakers are prone to loose rivets that bind it’s layers together coming apart. Replace if the Circuit Breaker has failed structurally.
11. Check the rectifier disc and insulation washer. Are they burned, melted or loose? If so replace the disc and washer or replace it all with a new diode.
12. Check the cast white metal Switch Shaft part (part# 20-70) that the Whistle Handle mounts too. It should have 2 blades cast onto the side. If they are broken or partially broken replace the part. Part# 20-70 is getting very hard to find. Many replacements are miscast and don’t work very well without a lot of extra work.