Hotpoint wmf 740

[fasetester]

This machine wont start Door lock clicking flashing door in display checked motor brushes ok checked connections on pcb cant get door lock out to check it wont come out of machine it moves back and forward but wont come out dont want to force it any idea why it does not want to come out

[electrofix]

some of the locks get jammed on the front panel trying to get them out

have you tried loosening the front panel?

Dave

[fasetester]

Thanks dave Just after i posted i discovered that dont think it the interlock getting ohms reading between terminal 3-4 200ohms and circuit between 3-5 when locked have to test the rest of thè components to see if i can find the fault

[fasetester]

What is the wiring connections on wmf 740 thè terminals are left to right 3 4 5 which is c L N and does thè interlock run on rejuced voltage or 240v thanks

[murv]

This is an instant door lock.

The module sends short pulses of mains across 3-4 to move the lock to locked or the unlocked position.

I would check the motor continuity at the module plug as this checks the wiring and motor + motor plug in one go.

Usually a lock or motor circuit issue but I did have to swap a module on a similar model last week

Murv…

[fasetester]

Thanks murv so you cant test by power it up it dosent work like L N C what causes thè clicking is it a relay on thè pcb and would a open heater cause the fault is always lnterlock motor pcb related fasetester

[murv]

Not had a heater cause this problem but always worth checking heater and pump continuity.

There are a number of versions of the WMF740 with different electronics and software so not all versions may respond to a fault in the same way.

A triac on the module provides a pulse to lock the door. It then looks for the locked return signal if none then another pulse to try again. After several attempts it throws a door error (assuming not confused by another fault like a motor circuit error)

Murv…

[fasetester]

Thanks murv for your help can this machine be put in dianostic mode fasetester

[murv]

Sorry, no engineer diagnostic mode available. The manufacturer and some agents can do very detailed tests with their custom diagnostic kit but this is not available to the trade.

The module does do a self diagnostic on start and records a detailed list of any errors in memory. The current basic error code will show on the machine display, in this case ‘door’. Diagnostic software and a serial interface module are needed to access the detailed error list stored in memory.

Murv…

[fasetester]

Thanks murv so in your opinion thè triac is the most likely component to cause this problum if their is no visual damage to the pcb such as blowen tracks or burning fasetester

[electrofix]

wont be the door lock triac as you said the door lock is clicking. so what is happening is the board is not reconising the door lock has closed.; This could be because the door lock is faulty, the door lock return wire is faulty or badly connected or the board
plus a motor fault. you have checkede brushes, i assume you have checked the harness back to the board

Dave

[fasetester]

Thanks murv and dave for your help put motor and interlock back on took of display board to check it found one of the traces with some corrosion give it a scrape put all back togeather and away it went

so this information might help someone else out thanks again fasetester:)

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