Emergency: same day
For a line-down motor, where the fault and parts allow. WhatsApp us before you send it so the bench is kept free.
Yaskawa · C-channel, UTOPH, UTOPI, absolute
Yaskawa servo encoder repair: C-channel, UTOPH, UTOPI and absolute types
Older Yaskawa servo motors, and the Allen-Bradley 8500 series built on them, use incremental encoders with UVW or a multiplexed C channel, and 12 or 15-bit absolute encoders with a battery. We decode and test these signals, repair or replace the encoder and align it. For newer Sigma serial encoders, send the model and we confirm the approach before you ship.
Repair turnaround you can plan around
Send a photo of the nameplate first. We confirm whether the motor is repairable, and the quote, the same working day.
Urgent: 3 working days
Repair, encoder alignment and test, counted from the day the motor reaches the bench and the quote is approved.
Standard: 7 working days
Full repair, encoder alignment, run test under load and a printed test report.
- Free repairability check from a nameplate photo
- Printed test report with every motor
- Written warranty, terms stated on every quotation
- Pickup can be arranged; parts that must be imported are quoted with their own timeline
01Models
Encoder models we test, repair and replace
| Encoder type | Examples | Counts per turn | Typical motors |
|---|---|---|---|
| Incremental ABZ with UVW | UTOPI | Varies | SGM, SGMG, SGMS and older series |
| Incremental with C-channel commutation | UTOPH-81AWF, UTOPH-81AUS | 8,192, 16,384 or 32,768 | SGM, SGMG, small SGM without Z |
| 12-bit absolute | With S, R and battery lines | 4,096 | Small SGM motors, Allen-Bradley 8500 |
| 15-bit absolute | With S, R and battery lines | 32,768 | SGMG, SGMS |
| Nemicon ABZ/UVW | USAEE motors | Varies | Yaskawa USAEE |
| Incremental ABZ/UVW | USAIKM motors | Varies | Yaskawa USAIKM |
| ABZ with tachometer | TFUE series | Varies | Yaskawa TFUE |
| Spindle ABZ | Yaskawa and Mazak spindles | Varies | Spindle motors |
C-channel encoders send commutation and index on one pair of wires; they must be decoded before the UVW edges can be checked.
02Faults
How these encoders usually fail
- Missing or wrong commutation from a C-channel decoding fault
- Battery alarm and lost multi-turn count on absolute types
- Connector and cable faults on 17-pin MS and small AMP connectors
- Encoder disc contamination after seal failure
- Encoder changed without alignment, so the motor trips or overheats
03Identify
Reading the label
Yaskawa encoder part numbers often start with UTOP, such as UTOPH-81AWF or UTOPI. They are not always printed on the encoder board; the cover or the motor model, such as SGMG-13A2AB, helps identify the type.
04Motors
Motors fitted with these encoders
Yaskawa SGM, SGMG, SGMS, SGMP, SGMD, USAEE, USAIKM and TFUE motors, Yaskawa and Mazak spindle motors, and Allen-Bradley 8500 series digital servo motors.
05Service
What we do
Test and repair
Every check on the feedback test list, before and after repair.
Alignment
Commutation set to the rotor at every pole pair.
OpenMemory programming
Motor data written to a replacement encoder.
OpenReplacement
Matched encoder fitted, aligned and run tested.
Open06FAQ
Questions
Can you test a Yaskawa C-channel encoder without a Yaskawa drive?
Yes. We decode the C channel into U, V, W and Z and check them against the rotor.
What causes A.810 or A.830 alarms?
On many Sigma drives these relate to the encoder backup or battery. See our encoder alarms guide.
Do you repair Sigma-II, Sigma-5 and Sigma-7 motors?
Yes, we repair these motors. Their 17 to 24-bit serial encoders are handled case by case; send the model first.
Free downloads for your maintenance file
Printable one-page sheets from our bench. More on the resources page.
Servo motor encoder quick reference
Encoder families, interfaces, counts per revolution and the motors they sit on: Fanuc pulsecoders (alpha A64, A1000), Mitsubishi OBA/OSA, Yaskawa UTOPH, Tamagawa, Heidenhain ECN/EQN/ERN and SICK SKS/SRS/SRM.
PDF · 2 pages · 8 KB · free, no sign-up
Download PDFServo encoder alarm quick sheet
Common encoder and feedback alarms on Fanuc, Yaskawa, Mitsubishi and Siemens drives, what each usually points to, and what to check on the cable and connector first.
PDF · 1 page · 4 KB · free, no sign-up
Download PDF07Enquiry
Send the nameplate or encoder label
A clear photo of the motor nameplate and, if the cover is off, the encoder label is enough to start. We reply with whether it can be repaired and a quote.
Message received
Our team replies by email or WhatsApp, usually the same working day. For a line-down motor, WhatsApp +91 97866 22233.