Asko W6342 Tripping Circuit Breaker - Hot Wash

Summary

Quick repair of an Asko W6342 that was tripping the earth leakage circuit breaker (safety switch) only during hot washes. Blog includes a tear down of the front panel electronics.

Asko W6342

Symptoms
Following a decade of hard work washing, the ever reliable Asko was tripping the 40A safety switch in the house power box. Changing the wash to cold prevented the tripping.

Diagnosing
Knowing that the internal heater or associated circuitry may be faulty, the rear panel of the Asko machine was removed and the heater element checked. Using the ohms range the element measured 25R which appeared to be acceptable. Time to take a peek under the hood at the electronics.

Removing the top metal cover on the Asko, a ten year single page machine electrical schematic was found inside the machine.

W6342 Original Machine Electrical Schematics

Checking online for some keywords shown on the electrical diagram a manual was found for the WM25 at Appliance Diagnostic. Pages 16 to 20 of the manual contained a plethora of detail regarding the operation of the Akso and the operational cycle.

Front Control Panel

The front panel is removed with a screwdriver and levering some well-placed clips. Once the cables are unplugged from the unit the control panel comes out as a single assembly.

ASKO W6342 Control Panel

ASKO W6342 Control Panel Rear

Removing the buttons from the front control panel and opening the unit shows two PCB's.

ASKO W6342 Control Panel Internals

Pulling the two boards out from the housing a visual inspection was performed and basic measurements of the relays and SCR shown to the right on the PCB below.

 

ASKO W6342 Logic and Power PCB's

For those interested the Asko W3642 used a Freescale MC68HC908AP32 processor as the brains for the operation.

Asko Freescale CPU

With no visible issues on either PCB or apparent faults with the parts it was back to the heater element.

Heater Element Insulation Testing

Both the power connections to the heater element were removed however the earth connection was left connected. A Honeytek A60B Insulation Tester was used to check between the internal heater element and the outside earthed casing. 

Honeytek A60B Insulation tester

The measurement shown on the tester was markedly below the Kilohms region indicating there was some breakdown of the insulation. After a decade of washing this was not surprising. Below is an image of the old element.

Asko Heater Element

A new element was ordered from Nation Wide Spares and changed for the damaged element. A great reference video for replacing the element is available at RepairClinic.

Once the Asko was reassembled a warm wash was performed to ensure that the safety switch did not trip and to verify there were no leaks from the newly installed heater element.