F&P IW711 Dead

[fastbike]

The pump on my 4 year old F&P IW711 was making an intermittent squealing noise, so I removed it for a clean, lubed it and replaced it. No signs of any damage, it spins freely and I have checked the resistance at 33 Ohm.

When I turned the machine back on and started a wash cycle, after 5 seconds there was a loud “POP” and the machine died. (It also blew the circuit breaker on the electrical board.)

As the machine is out of warranty and F&P want an arm and leg for a new control board, I opened it up. The 4 Amp micro fuse had blown.

I’ve soldered in a new fuse, and reconnected the controller to the earth and AC wires only (i.e. not connected any of the other wiring harnesses). When I turn it on at the wall switch, it blew the fuse again 🙁 So now it’s dead – awaiting my attention.

I’ve taken another look at the control board. Nothing appears to be damaged. I’ve checked all the AC components from the fuse through to the rectifier and none are shorted out.

I had read that some earlier machines (mine is phase 6) routed the power supply via the pump and diverter valve. This machine does not appear to, as the pump is controlled by a Triac, and the valve by a power MOSFET, so I’m confident the board should power up with only the earth and AC lines connected. (In any case it should not fry the board if the other connections are not made !).

Does anyone have a circuit schematic for the controller (item SD11) ?

Or can you offer any advice apart from buying a new controller board.

And was it something I did when replacing the pump, or just coincidence ?

Thanks in advance.

[fastbike]

Re: F&P IW711 Dead

I’ve just checked the resistance for components while the machine is open.

Pump 33.3 Ohm
Diverter valve 2.1K
Hot valve 64.1 Ohm
Cold valve 63.5 Ohm

Motor windings are approx 32-33 Ohm

I had wondered if any of these were faulty, and caused the initial blowout.

Could someone please confirm these are within tolerance. No point putting in a new control board if the peripherals are going to blow it again 😳
Is there anything else I should check while I’m there ?

P.S. I’ve just checked the date on the back of the machine and it was manufactured in late 2002 – so it is actually 5 years old. Time flies.

[fastbike]

Re: F&P IW711 Dead

OK, after a bit more investigation, I’ve found the problem. It seems when I tipped the machine back and removed the pump, a small amount of water splashed onto the diverter valve wiring, shorting it out !

The diverter valve is driven by a MOSFET (Q862) and a pair of fast rectifier diodes (D861/2).

These diodes are shorted closed, 👿 thus explaining why the fuse blows when power is applied to the board.

I have ordered replacements for the diodes and MOSFET, which will be here next Tuesday. Instead of $175 for a new controller, I’m up for approx $5 in parts 😀

Be warned !

HTH

[fastbike]

Re: F&P IW711 Dead

Here’s the final outcome in case anyone else has a similar problem. Also my research has found the diverter valve failure is a common problem – and when it fails it takes out the controller board. (Interestingly, the replacement diverter valve has a PVC cover with “DO NOT REMOVE THIS COVER” printed on it. A case of the manufacturer finding a problem, and deciding it is cheaper to keep quiet about it ? )

Anyway back to the eventual solution.
I replaced the following components:
– main fuse (slow blow 4A, 250V for the 230VAC machines)
– Diodes D861 and D862 with equivalent parts (600V/1A, ultrafast rectifier, OnSemi MURS160T3)
– MOSFET Q862 (STD2NC60, this part is no longer available but STP3NK60Z is a good substitute)
– driver transistor Q861 was replaced with a generic NPN switching transistor (BC847B).

These are all surface mounted components so ensure you use a temperature controlled soldering iron with a fine tip. Carefully remove the old components with solder wick without damaging the board or adjacent components.

If you have any questions please PM.
HTH

David

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