โ Fadal Resources
Step-by-step diagnostic procedures for legacy Fadal VMCs, tested values and connector checks for the tech doing the work on the shop floor. Have a fault code but don't know what it means yet? Start at Fadal Fault Codes & Troubleshooting to identify the issue first.
How to Test a Resolverโผ
A resolver fault means the axis controller card isn't detecting the returning sine wave signal from the resolver. Test it with a voltmeter before assuming it needs replacement.
| Check | Expected Reading |
|---|---|
| Pair A resistance | 70 to 80 Ohms |
| Pair B resistance | 190 to 220 Ohms |
| Pair C resistance | 190 to 220 Ohms (B and C should match; exact value depends on manufacturer) |
| Coil-to-coil | Any pin combination outside the three pairs above must read open circuit |
| Short to ground | No pin should be shorted to the resolver frame/case |
| Pair A voltage (connected) | 1.7 VDC |
| Pair B and C voltage (connected) | 3.5 VDC. Pair A runs directly to the 1010 axis card, J2 bottom bullet connector. |
Also check the 6-pin Molex connector at the motor for corrosion or worn pins, and the bottom bullet connector at the 1010 axis card for a loose fit, both are common causes of intermittent resolver faults that aren't actually a bad resolver.
Need the Part?
Shop encoders and resolvers, or all Fadal parts. Can't identify the part yet? Email support@thecncsource.com with your machine model and symptoms.
