*Another* Bosch dishwasher problem!

Same model as the one with the soap dispenser, as it happens...
Odd, this. SWMBO reported that the machine was making horrible grindy noises while it was pumping out, but not while it was washing. But of course, rather than switch off and wait for me to come home and take a look, she lets it keep running until the end of the cycle and emanation of what she described as an 'electrical' smell - I'm not entirely sure which came first. Bless.
Anyway - sounded to me like a Foreign Body in the impeller, so I took out the filters etc, unscrewed the cover in the sump, and sure enough, found a hard lump of crud in the pump chamber where i'm sure it was doing no good at all to the impeller.
Put it all back together, and the pump was clearly spinning fine now. However, the machine now keeps running when you open the door; which you have to do as all the controls are hidden on the top edge. I really don't know what's going on - looks like a failure of some detector switch or other, but what I really can't fathom is how this can be related to the original problem of the part-jammed pump. Can't believe it's coincidence??
Any thoughts
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Is it just the pump that is running constantly? If so it's possible that the triac that runs it has died due to the overload. They are only a couple of quid - but getting to it might be challenging.
Steve
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stevelup wrote:

Ooh - yes, exactly that. So a blown triac would cause these symptoms then?
Have had a look at the exploded parts diagram for my model (SGV4313GB) at http://www.bshappliancecare.com/Bosch/boschspares.html but can't see anything... is it likely to be physically on the pump motor or remote somewhere?
I don't know much about electronickery, but I can certainly desolder and replace a triac if I know where it is... no doubt if the Bosch engineer comes he'll just dump the whole motor and replace it at cast cost :-(
Dvaid
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Try tracing the motor wires back to a controller, I'd expect the triac to be on a PCB in the there.
If you can post a decent picture of such a PCB I'm sure it can be identified.
Failing that try ukwhitegoods if you need a replacement.
cheers, Pete.
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Hi
The control module is always in the door on Bosch dishwashers (or on every one I have ever seen).
Steve
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I don't know this model but it's also possible that it has an overflow/ leak detector which has tripped. On my AEG dishwasher there is a float activated switch in the base. If water builds up there it trips and runs the pump continously - even when the machine is switched off - so that you have to actually unplug it from the wall the stop it. The detector is manual reset so that just mopping out the water isn't enough, you have to reset the switch too. If I were in your situation I'd take the panels off and have a look in the base, If you can see a large-ish lump of expanded polysytrene look for a switch activated by it. If it's wet there or if you may have knocked it during previous maintenence then you'll need to reset it.
Good luck.
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Calvin wrote:

Now that *is* interesting... I spent ages earlier this evening pulling off panels and trying in vain to find a PCB, and also to remove a plastic cover from where I think the triac *might* be hiding, and eventually gave up in disgust.
However, I did notice that the base of the machine had a quarter-inch of stagnant water in there... I spotted the float switch, and thought it looked like it must be perilously close to tripping, and made a mental note to tell the engineer when he comes. Never occurred to me that it might actually have tripped, and that this could set the pump off.
I shall investigate further tomorrow!
Thanks David
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Lobster wrote:

Hoo-rah! That was exactly the problem. I dried out the base, and it's now working fine. Thanks very much indeed as you've definitely saved me an unnecessary engineer call-out (and I'm very relieved I hadn't started de-soldering PCBs!! ;-) )
It's odd that this happened just at the same time as the pump got the crud in... the only thing I can think of is that the float switch was teetering on the threshold of tripping, and maybe I put my weight on the inside of the machine enough to send it over the edge. God knows where the leak is coming from, but judging by the yuck factor of the leaked fluid it looks like a very slow one. (Watch out for the next installment on uk.d-i-y in a couple of months: "How do you track down a slow leak in a dishwasher?")
Thanks again David
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Lobster wrote:

<snipped tale of knackered machine>

Well, I'm back - but in just less 1 month - to ask "How do you track down a slow leak in a dishwasher"?!
The machine tripped again, and the base tray of my Bosch is again filled with water (as in, about 3-4 mm deep), so there is indeed a small leak. I have the side panels off, but can't for the life of me see where it might be coming from.
Where do you start?
The internals of the base of the machine are incredibly cramped; there's no room to see anything or get tools in there. I can't even get in to dry out the base tray properly (the whole base tray is wet), and I can't see anything else (pipes, connectors etc that is damp or leaking).
I'm sure a dishwasher engineer would be able to resolve this - but how??
Thanks David
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On Nov 7, 8:08 pm, Lobster

Try the forums at ukwhitegoods.
Out of interest, are you in a hard water area, if so do you use salt or just 3in1 tablets?
cheers, Pete.

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1. Get hands on Haynes Dishwasher Manual for the general advice. 2. Our 1988 model Bosch S710's outlet pipe was brittle and had a slight crack - manky water all over the base tray (roughly equalled evaporation rate). 2.99 or something from Screwfix. Had to remove a red 90 degree elbow where it attached to the drain pump to fit the Screwfix pipe's rubber end directly. 3. I took it into the garage (for lots of space) and got my brother to help taking panels off and assist lifting the machine off the base tray. It had gone slightly rust-scabbed, so a wire brush and smooth white Hammerite sorted that out. Putting the machine back on the base tray required accuracy - and wear toe caps! 4. The inlet hose since developed a leak - another hose was sourced for minimal from Screwfix, I dragged the DW out from under the worktop, took off the front kickstrip, removed the pipe from the inlet valve (after turning off the water), hacked the fitting off the end of the leaking pipe and pulled it out from the rear of the DW. Threading the new one in was easy with an assistant, a desk light, and finding an easier route through for the new (longer) hose.
If it's leaking higher up the machine, it will feel damp higher up when you start removing more panels. Get egg boxes etc for the screws and make copious notes!
James
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On 7 Nov,

A picture tells a thousand words. I now use a digital camera rather than a sketch and notes. It's much more accurate, and better for the bit you forgot about.
--
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I only do that to get a 2nd opinion/identification/gather data from a spec plate when I C.B.A. to copy it all out. Dismantling an appliance, I will always reach for a large piece of cornflake box and a biro and scrawl "2 screws holding top cover on at rear L&R"... "motor wiring connector, red wire towards top, purple towards bottom" "cable tie cut at motor mounting"... and so on.
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wrote:

Maybe here: http://www.teamhack.de/index.php?site=anleitungen at number 10.
It's German, so I'll summarize.
Symptom: Slow dribbling leak from the left side water widget overflow hole?
Cure: Fat black hose clogged, clean out (it's marked in green on the photos). Best way is to take off bottom tray when unit is on the back...
HTH,
Thomas Prufer
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