UniMac Washer Error Code Ed02: DC Bus Overvoltage
Ed02 on a UniMac UC-series washer-extractor with a motor drive means the DC bus voltage went too high, so the drive stopped the cycle to protect itself. Power down, avoid touching any wiring, and try a lighter load. If Ed02 returns, line voltage and the drive need checking by a technician.
High: the drive shuts off to protect itself, and cycles will not complete until the cause is found.
What does UniMac error code Ed02 mean?
On UniMac UC-series washer-extractors such as the UCH020GNF with the motor drive, Ed02 means the DC bus voltage is too high. Inside the drive, the incoming AC supply is converted to a DC voltage that powers the motor. The drive watches that internal voltage. When it climbs past the limit, the drive protects itself by shutting off, and the cycle stops with Ed02. Several things push that voltage up. Line voltage that runs high at the machine raises it directly, and surges on the supply circuit can spike it. A motor slowing a heavy load can feed energy back into the bus. In rare cases the drive board itself misjudges its own bus voltage. The code applies to Design 2 and 3 models only, and high line voltage or a surge in the supply are the first things to rule out.
Affected models and control systems
Listed for UniMac UC-series washer-extractors with a motor drive (CHM495R family, 20-100 lb), such as the UCH020GNF. The manual limits Ed02 to Design 2 and 3 models.
Code numbers and their meaning can change between control generations. We match the full model and control before acting on a code.
What you may notice
- Ed02 on the display, often during a spin or while the drum slows
- Cycle stops partway and the drum coasts down
- Lights or other equipment on the same circuit flicker around the time of the stop
- Code appears more with heavy loads
Possible causes
Listed in UniMac's documentation
- Line voltage that runs high at the machine
- Voltage spikes on the supply circuit
- Motor that feeds energy back while slowing a heavy load
- Drive board that misjudges its own bus voltage
Other likely causes — what usually sits behind error code Ed02 on this control. A technician confirms which one it is before any part is replaced.
- A utility voltage on the high side of the 208-240 V range at the end of the day, when the load on the lines drops
- Other large equipment switching on the same panel and sending spikes down the line
- A heavy load braking hard from high spin speed, which pushes the bus up
Safe checks before calling for service
- Power the machine down, check the line voltage if you have a qualified person who can do it safely, and power up again.
- Do not touch wiring inside the cabinet.
- Try a lighter load to see whether Ed02 returns.
- If it does, call us.
- Note the time of day and whether other equipment was switching on.
How a technician diagnoses error code Ed02
- Read the code and record the load size, the cycle step and the time of day when Ed02 appears.
- Measure the line voltage at the disconnect, both idle and under load, and check for spikes.
- Inspect the drive input connections for tightness and heat marks with the power locked out.
- Check the drive's bus voltage reading against its specification where the drive allows it.
- Replace the drive only after the supply is ruled out as the source.
- Measuring line voltage and the drive's DC bus means working on live circuits, and the DC bus can hold a charge after power is off.
- A supply problem on the building's side needs an electrician or utility, and a technician can document it.
- Replacing a drive without confirming the supply would simply repeat the shutdown on the new part.
How error code Ed02 differs from similar codes
Ed02 is an overvoltage on the DC bus. Ed05 and Ed08 are overcurrent codes, and Ed06 is a drive overheating code.
Technical reference
- Document
- Washer-Extractor Programming CHM495R_SVG, Part No. F8208501ENR10, March 2017, Error Codes (pp. 36-37)
- Maker documentation
- UniMac owner support
- Edition
- Part No. F8208501ENR10, March 2017
- Models / control
- CHM495R family washer-extractor front-end control (20-100 lb)
- Section
- Error Codes table, pp. 36-37 (E Pr only on Design 1 models; Ed01-Ed11 on Design 2 and 3 models)
- Checked
- October 2026
We use the maker's document to read the code and do not reproduce it. Always confirm the complete model and control before applying these steps.
Related UniMac washer error codes
Can high line voltage damage the washer?
It can stress the drive, which is why the drive shuts off. Have the supply checked if Ed02 repeats.
Why does Ed02 only show with heavy loads?
A heavy load slowing from spin returns energy to the drive, which raises the bus voltage.
Is it safe to keep running lighter loads?
If light loads run cleanly, you can continue until the visit. Stop if the code returns.
Need help with UniMac error code Ed02?
A technician confirms the cause on site and gives you the price in writing before any work starts.