Hotpoint Aquarius FDW60 dishwasher controller board

Some information on the Hotpoint Aquarius FDW60 dishwasher controller board for anyone interested in DIY repairs. The following was gleaned from an evening of poking around. I'm not certain about anything here, but hopefully it might be of use to someone else. If you have any feedback please post a comment at the end of this posting.

Warning: if the dishwasher power switch is on this board will have live mains (230V) PCB traces which are a shock hazard. Only access this board if you know what you are doing. It may also void your warranty.

The underside of the controller board. The large chip is the MCU (Renesas 6433662B94H). The triacs near the connector at the bottom of the photo are a 4 Amp STMicroelectronics T4-0560 (large triac on left) and 5 smaller triacs: Z7SY424 (also ST Microelectronics, but sorry can't find the datasheet). The triacs are located on the neutral (N) side of the load so the inputs to these triacs float at 230V AC when off.

I don't know what the 8 pin IC to the left of the MCU is – I'm guessing an EEPROM. The microswitch is the "Delayed Start" front panel button. The connector at the top-right connects the LEDs and switches on the left side of the dishwasher's front panel. The large traces at the bottom left provide power for the water heater.

This photo is the top side of the controller board. Visible are: black relay for heater on left. Buzzer (black disc in the center). The white wire pair connecting to the board at the bottom of the photo is (I believe) the water intake flow meter. The black wire pair I guess to be a temperature sensor. The blue component just above the barcode label is a combined crystal/capacitor for the MCU clock. Misc components to the left of the board are a mains to DC power supply for the low voltage electronics.

The 4 pin header to the right of the buzzer seems to be a diagnostics port. Pins on this header from left to right connect to the MCU's NMI, RXD, TXD. The last pin I'm not sure about. I thought ground would be the obvious choice, but I was seeing -5V on RXD and TXD relative to this pin. Maybe it's a +5V. This needs to be investigated further another time.

This is a close up shot of the MCU. The first digit is a '6' is difficult to see in this photo. The marking is 6433662B94H.

This is what I could figure from the mains voltage (230V AC) connector on the controller board:

White, Gray and Brown are sense wires (MCU senses presence of 230V AC or not).  Blue,  Red/Blue, Black, Violet, Red and Cyan drive a load (motor or actuator).

Orange	Provides 230V AC power to the board.
White	Sense: ? water pressure -- it can sense if wash arm is obstructed
Gray	Sense: Salt related ?
Brown	Sense: float switch on drip tray – triggered in the event of a leak
Blue	Wash pump motor
Red/Blue	Lower wash arm valve
Black	Drain pump
Voilet	Salt related?
Red	Water intake valve
Cyan	Detergent release door

Other information:

My 'howto' on unsticking the FDW60 drain pump:
http://jdesbonnet.blogspot.com/2010/11/hotpoint-aquarius-fdw60-drain-pump.html

Interesting dishwasher application note from Renesas:
http://am.renesas.com/applications/consumer/home_appliance/dishwasher/dishwasher.jsp

Excellent dishwasher hack here ("Arduino Controlled Dishwasher"):
http://www.neonsquirt.com/dishwasher.html

Please add any additional information or corrections in the comments below. Thanks!

Hotpoint Aquarius FDW60 dishwasher drain pump repair

A few years ago our 2004 Hotpoint dishwasher (Aquarius FDW60) started failing in mid cycle with a flashing "Eco" and "Fast" LED. The underlying cause was that the grey water drain pump wasn't pumping. There was precious little information about reparing the device on the internet. Faced with a repair bill of at least €140 we were close dumping and replacing it. I figured there was nothing to lose by investigating the problem myself and after a little puzzling over the layout of the various inards of the device I eventually located the drain pump, disconnect it, manually rotated the impeller a few times with a srewdriver, reconnected it... and sure enough everything was back to normal.

Two years later after flawless operation, the problem has returned. This time I thought I'd document the repair procedure in case it's of use to anyone else.

First a caveat: don't try this unless you are comfortable with DIY repair and have at least a basic understanding of electrical safety. The instructions here worked for me, but may not be the "correct" way of doing things. If you do decide to proceed YOU DO SO AT YOUR OWN RISK. Also, if there is any warrantee remaining on the appliance it may be voided by your attempt to repair. Feel free to add feedback below if you have any interesting information to add.

The tools you need for this are:

• Phillips head screwdriver (number 2), but you might get away with a flat head
• Torch (optional)
• Bucket (optional)
• Rag (optional)
• Brush and/or vacuum cleaner (optional)
• FDW60 manual (optional)

Empty any water remaining in the dishwasher. Remove the filters and drawers (the top drawer requires that you to remove a plastic stopper at the end of the drawer rail). Use a rag to mop up any remaining water in the drain well. Switch of the unit and remove power at the wall socket or fuse.

Before disconnecting the cold water in ensure that the water supply to the appliance is OFF. This is usually accomplished by means of a valve leaver near where the hose connects to the water supply. Leaver perpendicular to the pipe usually means OFF. Have a bucket and rag ready to catch any residual water in the hose.

Same applies to the grey water outlet hose. This water may have a foul oder -- so be prepared.

Ensure that the power cord and the two water hoses are free to move as you gently pull the appliance out.

Place some newspaper on the ground and have some rags on the ready. Stuff a rag in the drain well to absorb residual water. Gently lay the appliance on its side. Be prepared from some water to seap out. The bottom of the appliance is now exposed. Use a brush or vacuum cleaner to clean the bottom.

Double check that you have electrically disconnected the appliance (don't just rely on the appliance on/off button!). Best to physically disconnect the power cord from the wall socket. If you can't do this then trip the fuse associated with the appliance. Verify there is no power by switching the device on and ensure the power neon does not light.

The bottom panel can be removed by unscrewing 6 (Phillips Head Size 2, I think) screws marked by red arrows in photo. You may need to temporarly remove the front legs to access two of the front screws(just twist the leg until it comes out).

Most of the essential dishwasher components are now accessible. The drain pump can be removed by unscrewing one screw (see photo) and twisting the pump assembly.

The impeller should now be visible inside the pump chamber. Use a pen or screw driver to rotate the impeller a few revolutions. There will be some resistance due to the pump motor – that is normal.

Ensure that there are no foreign objects stuck in the chamber (use a torch to illuminate the chamber while rotating the impeller). In my case I found a pumpkin seed!

Reattach the pump assembly (be careful to ensure the o-ring seal is still there).

Replace the bottom panel. Bring the unit upright. Reconnect power and water hoses. Run a "Prewash" cycle to test.

That should be it!

Boot note: On my first attempt at reattaching the pump assembly I failed to engage all three posts of the bayonet twist lock mechanism (the one at the back which isn't easy seen had not engaged). This resulted in water leaking during my test which caused the float switch activate. This manifests itself as as flashing "Eco" LED and the drain pump runs continuously. Once the pump was attached properly everything ran smoothly.

Update (24 Jan 2011): I've added additional information about the this dishwasher's controller board in this blog post.

Update (7 Mar 2011): A Hotpoint technician told me that this can often be solved without removing/opening the unit by using something like a wire coat hanger to unstick the drain pump impeller. I've never tried this, so I can't comment on its effectiveness and it probably won't help if there is a foreign object lodged in there.

Update (25 May 2011): Impeller got stuck again today. This time I tried the coat hanger trick that was suggested to me by the Hotpoint technician. It worked! I had to do it twice... first time the pump started working, but it sounded rough and then jammed again. The second time it again sounded rough for a few seconds but recovered and seems to be fully back to normal now. There was probably a foreign object in the pump chamber that got expelled eventually. You need a wire coat hanger and make a right angle bend like this:

The horizontal part (running parallel to my measuring tape) goes into the drain hole. See photo of the underside of the dishwasher above to get an idea of what's going on. About 10cm - 11cm is what you need to reach the impeller. Then just wiggle it... all it takes is just the slightest movement of the impeller to unstick it. Of course if you have a large foreign object stuck in there this probably won't help – you'll need to disassemble the pump as described in the main part of this post.