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Bypassing IR sensor/detector in Fisher Paykel DD24 dishwasher

Lucy Electronic

Mar 11, 2022
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Mar 11, 2022
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My Fisher Paykel DD24 no longer detects that the drawer is closer, and subsequently won't start, giving 3 beeps and a lower tone beep. It's been on it's way out for awhile, intermittently stopping the wash cycle, been able to mitigate the issue somewhat by shimming the drawer open 5-6mm. But the other day no amount of shim would let it start.

I'm able to trigger all the functions of the dishwasher from the hardware test mode, which doesn't seem to care about the status of door. Supposedly the "keylock" symbol will appear in that mode to indicate the status of the door (but doesn't) so I'm reasonably confident in my hypothesis that the IR sensor / detector has gone bad.

They live on the main PCB which is in the drawer, and the emitter shines out to the chassis, through a lightpipe which reflects it back to the detector

The emitter and detector are separate surface mount components, I'm not sure which one is not working. I also do not have any info about the parts themselves, otherwise I'd try replacing them.
A new PCB is a few hundred dollars so I'm motivated to try a few hacks first.

I would like to trick the microcontroller, and I've thought of the following:

1) short the detector
2) solder a variable potentiometer across the detector in hopes of dialing the resistance that will cause the microcontroller to register the threshold current. (I'm assuming the normal operation is that once the detector detects IR light, it passes more current?), I may be able to use the hardware mode live and adjust the potentiometer till I see the "keylock" symbol

3) try to replace the parts, not sure where to start..

In terms of operation, I don't believe there will be much drawback to having the dish washer think the door is always closed. While in operation the lid moves down mechanically and makes the drawer difficult to open. I obviously won't try to start it while it's open :) either
 

Harald Kapp

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Nov 17, 2011
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In this forum someone solved the issue by re-soldering the connections to LED and sensor (scroll down to end of page).
 

Bluejets

Oct 5, 2014
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More than likely a safety switch put there for a good reason.
 

Lucy Electronic

Mar 11, 2022
6
Joined
Mar 11, 2022
Messages
6
More than likely a safety switch put there for a good reason.

It would definitely cause issues if I started it up while open, the lid would come down and maybe get damaged, not to mention water spraying inside the machine (if I let it get that far). Again, it would be silly to start it with it open (the start is on the front panel) so I'm not too worried about starting it accidentally. During the wash cycle, the lid being physically down stops the door from opening mechanically so I don't see any danger there.

It's an 9 year old machine at this point, so replacement is definitely an option.. but if I can get a few more years out of it, with a hacked solution then I will
 
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