[davepi]

Re: Bosch SGS5312GB – cycles taking too long

Martin wrote:

davepi wrote:
Any helpful suggestions?

Dave, You replied to Penguin45’s 2nd post on the subject, but did you take on board his 1st I wonder?

That was about fat deposits in the left transfer pipe. Thing is, I don’t know what the left transfer pipe is! I did find some peas blocking something once I’d removed all the filters, but clearing them out made no difference. Are you able to tell me where to find this pipe?

I tried it again with the covers off and have managed to get it to fail. It got to a point where it was running but never turning the element on. A thump on the top of the door near the control board fixed that for a minute or two so I’m pretty sure it’s something wrong with the control board. Probably a poor connection; a dry joint on the DC side of the relay; or a dodgy relay. I’ll pull it out tonight and have a look at it. Apart from the relay solder connection fault, which I fixed about 3 years ago, are there any other known controller board faults?

cheers

Dave

[davepi]

Re: Bosch SGS5312GB – cycles taking too long

Right. I’ve managed to measure the element resistance which is 22.5 ohms which sounds about right for the specified 2.4kW power consumption for the machine. When I ran it with the side panel off, it actually got up to temperature and I was able to monitor when the element was being switched on. Everything looked okay so I assumed that I must have fixed a poor connection while I was probing around with the DVM. But when I ran it after putting it all back together it’s gone back to not being able to heat the water up again and taking too long! Arrrgggh!

Please. Any helpful suggestions?

thanks

Dave

[davepi]

Re: Bosch SGS5312GB – cycles taking too long

Penguin45 wrote:The poster appears to be intent on working this out for himself. If you have nothing constructive to add, please leave the thread alone.

That was the plan, but even with a degree in Electrical and Electronic Engineering, I have neither a service manual, training nor extensive experience of repairing dishwashers!

Is the machine’s plumbing that has been alluded to and the heater element accessed from inside the machine, or do I need to take off any back or side covers to get at them?

I do enjoy fixing things myself and am willing to work it out for myself, but being a lazy b****r, have been appreciative of the advice that people have given.

thanks

davepi

[davepi]

Re: Bosch SGS5312GB – cycles taking too long

Right, I have now checked the temperature and it struggles to hit 47 deg after an hour on the 65 deg wash. It MUST be the element. I don’t think it’s the dodgy relay solder joint on the control board, as if that had gone high-resistance it would have burned out by now.

How easy is it to check and change the element?

Dave

[davepi]

Re: Bosch SGS5312GB – cycles taking too long

Yeah, had that problem a couple of years ago and fixed it; only the darlington array that allows the micro to drive the relays also got taken out! A trip to RS and 50p sorted that out.

The machine is heating the water, but I wonder if it’s happening too slowly or the thermostat is bust meaning it gets too hot – I will check that.

I had a look at the filter in the base of the machine, that you’re meant to clean every week, and found a layer of milky gunge over it – something to do with the softened water perhaps? Bosch tell me that they don’t advise people to run their machines from a water softener, but wouldn’t/couldn’t tell me why. Anyone know why that is?

The machine is about 7 years old – at the end of the day is it worth repairing?

[davepi]

Re: Bosch SGS5312GB – cycles taking too long

gegsy wrote:The soil sensor or to give it its correct title Turbidity Sensor is mounted in the instantaneous heater unit. You can’t gain access to the part of it that will be gunged, only the sensor pcb itself is accessible.

Keep running it through on hot washes to see if gets any better. Failing that the sensors “may” be faulty.

Greg

I’ve run it several times on the hot wash (65) and it is continuing to take over three hours. As well as the Turbidity Sensor, could there be other problems such as:

1. The element taking too long to heat up the water
2. A faulty thermostat
3. The fact that I installed a water softener a couple of months ago.

With regards to the water softener, I have turned off the dishwasher’s water softener and have stopped putting salt in it (the salt indicator is off so the machine is not asking for any). The house water softener is an electronic one which has been set up to soften only as much as is needed for the level of hardness of the incoming water main. Could this water softener be the problem and if so, what could it have done to the machine? I have noticed a small amount of froth in the bottom of the machine at the end of the cycle, but nothing excessive.

thanks

Dave

[davepi]

Re: Bosch SGS5312GB – cycles taking too long

Martin wrote:Gunged up soil sensor in the heater unit is the problem. That is caused by using cheap detergent or/or not using salt in the salt container when you should (hard water and all that!).

2 things you can do to try curing it are firstly, buy some dishwasher cleaning tablets and follow the instructions. Secondly, use a good quality detergent like Fairy Active Bursts and again, follow the instruction on the package! 😉

Hope that sorts it for you? 🙂

Thanks. I’ve run the machine with some Finish dishwasher cleaning fluid and the cycles have now reduced in time a but still taking a couple of hours. Where is the soil sensor and how easy is it to gain access to clean it?

thanks

[davepi]

Re: Bosch 6312 Dishwasher: No Heat

I am an electronic engineer and am shocked at Bosch’s attitude to the control panel problem. It is clearly a design fault whereby the PCB designer did not allow sufficient copper for the relay connection to the heater. Bosch technical support even had the cheek to suggest that this track was acting as a fusable link! A 10p fuse fitted to the PCB would be preferrable to having to replace the entire module at a cost of £100 + labour. Bosch clearly know it’s a design fault and are really not looking after their customers well.

My SGS5312 failed in a similar way and I repaired it myself by remaking the relay connection and replacing the 2003 darlington transistor array chip that drives the relays. Now all working fine. This is obviously not a general DIY job, so I would not recommend this approach for all unless you have access to good electronic assembly facililities.

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