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The machine always fills at the start of the programme – any programme – and pumps out at the end of the first stage. After that it often does not fill on subsequent stages but it “thinks” it has and will carry on and complete the stage with the main pump running and the tablet lying on the bottom but dry.
If you open the door and pour water in, it carries on operating normally, but may or may not fill for the next stage.
When it fails to fill, there is no voltage on the inlet valve, so it’s not just a stuck valve.
Must it be the programmer? If so a write off I think.
Thanks for any advice.you have an early system have you taken off the left side and checked for gunk in the pressure switch section
Dave
Sorry I should have said. Yes everything there stripped and cleaned, the corrugated pipe to the sump is clear, the pressostat operates and the microswitches seem good on test. However if I operate the pressostat m/switch during filling, it doesn’t stop the fill as I expected, it continues. I thought the pressostat was the primary level controller? If it isn’t, what is?
The pressostat does retract when machine empties, it isn’t sticking.
If I trigger the overfull/flood m/switch, it causes pump out as long as I hold it triggered.
Mikeno the water does not stop at once. normally the motor starts and the timer has remembered how long it took to fill to this level and time fills it from there
check the wires back to the timer, we have had them break at the bottom of the door
i know it fills at first but cant remember if micro is 3 term or 2. If its 3 then one could break and cause this sort of problem. also disconnect micro and do a resistance test between the 2 open contacts in case there is leakage
DaveThat’s interesting but a bit confusing. When it fails to fill, the pump runs with the machine empty so it’s not the pressostat that starts the pump. In fact operating the pressostat in any stage of the cycle, whether it has filled itself or not, doesn’t seem to affect anything.
I wondered about a wire break at bottom of door. Not the easiest job to check them all, so many unmarked and of the same colour -lots of blues and whites – and they change colour at the plugs and sockets on the right side bottom before going to the switches and the inlet valve! Lost without a wiring diagram.
The two m/sw test OK on a meter and operate cleanly with a click. The connections are the same as this photo.
“When it fails to fill, the pump runs with the machine empty”
if thats the case the machine thinks its full of water we just have to find out why
Dave
I think I’ve found it, not quite certain yet.
Checking the m/switches again, I found the NC contact of the flood prevention device (switch 2 in pic above) was measuring around 5 ohms. This supplies the inlet valve, interrupting it if the flood preventer activates. It works OK for the first fill but my guess is that it heats up and sticks and doesn’t work again until all cooled.
I removed the switch and bridged this connection (so now there is no flood preventer) and the machine ran a full cycle 🙂
It will have another run tmrw and if that works I will look for a new switch.have a look at the switch, some of them allow the cover to be popped off and you can clean the contacts
Dave
No I don’t think so, it’s a miniature switch (V3 standard), sealed case, made by Cherry. Not worth the risk.
Normally pennies – but a spare one from Bosch to the right spec (low force) is £21 inc postage! Part no 165256. Amazon £10.
Unfortunately it’s still intermittent with the switch bridged out.
I’ve traced the wires back to the controller and I’ve tapped into them an inch back from the controller. One is direct to neutral, the other is a switched live. When it doesn’t fill, there is no voltage on the live. So unless there is some other logic input to the controller that is inhibiting it, it must be the controller. Repair isn’t on, it’s driven by an SMD device, not a relay. I can’t think of anything that would inhibit it other than the float switch and the pressure switch but without a cct that’s guesswork. The float switch is disconnected and the pressure switch is working correctly.
I see there are used controllers around for £30 or so but where do you stop, what’s next? I still need the expensive m/switch too. With a new basic Bosch at £299 it’s probably the time to change. The machine has been very good for 16 years, all I’ve done in that time is clean the syphon thingy a couple of times (I’m in one of the hardest water areas in the UK and everything gets scaled up). I think the water softener resin is probably exhausted too.
So unless I get any brilliant suggestions, out comes the credit card!
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