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JBM  
#1 Posted : Tuesday, November 11, 2008 6:38:30 PM(UTC)
JBM

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I am trying to trouble shoot the timer on a Bosch SMU 3036 Dishwasher as it is not cycling past 3 0'clock (initial wash cycle). The water use to be incredibly hot - therefore the element isn't getting the signal to turn on and heat the water hot enough to advance the cycle.

I have checked the Element and while it has continuity, it remains stone cold.

I have already replaced the Timer, 2 High-Level Themostats (checked Thermostats and they have continuity) and Temperature Sensor switch (has continuity) - no change it still hangs at the wash cycle and we have to advance it manually to finish the wash - yet dishes aren't dry because of the element not heating as well.

Only thing to change is the Heating element (but has continuity so I don't think this is the problem). I really need to find a Bosch SMU 3036 Dishwasher Service Manual or schematic so I can check the timer connections are proper to the thermostats to ensure they are getting the right signal from the timer to heat the Element.

Where would I find this specific manual/ schematic, anywhere on the net?

Any assistance is appreciated.
I saw another manual posted but it is for SHU 3036 - different timer contacts.
Thanks,
JBM
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Gene  
#2 Posted : Wednesday, November 12, 2008 3:40:48 PM(UTC)
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You can find the wiring and circuit diagrams in the break down diagrams for the Bosch dishwasher Model SMU3036 UC/14 (FD 7507-7902)

Gene.
JBM  
#3 Posted : Wednesday, November 12, 2008 10:18:38 PM(UTC)
JBM

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Thanks Gene.
I have totally replaced the wires on the Timer to make sure they were in the right place. I checked for resistance across the (2) Hi-Level Thermotats (.8 ohm), resistance across the Heating element (1 ohm), yet I don't get a reading across the Themostat (which I believe is because it stay open until sent signal to lose to send power to the Heating element.

I recall someone mentioning to by pass the thermostat and see if the machine runs a full cycle - can this be done safely? If so and the machine does complete the cycle - does this mean the thermostat is no good

Is there anyway I can check across the terminals of the timer to know it is OK?
How do you reset the timer on this machine as I have heard about ?
Any other suggestions are appreciated as I am at my wits end by now trying to solve this as it doesn't seem to be the Heating Element - although it stays stone cold while washing and it is only the supply Tap hot water tat is washing he dishes currently? It has become more a matter of pride to overcome the machine.

Thanks, Blake
denman  
#4 Posted : Thursday, November 13, 2008 3:26:38 AM(UTC)
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I think you are measuring the resistances incorrectly.
It looks like you are measuring a parallel/alternate circuit path.
The heater should measure much higher than 1 ohm.
A 1 ohm heater would use 120 amps which is way too high.

Did you remove at least one wire from the device you were measuring just to ensure you do not measure an alternate path.

The thermostat contacts should close at 161 F, this tells the unit that the water is hot enough to proceed with washing. Bypassing it so the unit thinks it is full of hot water should not cause a problem.

But it does not rule out other parts.

A crude way of checking it would be to remove it and heat up the face with a soldering gun while measuring the resistance. It should close once it gets hot. Unfortunately this does not tell you at what temperature it is closing.
THIS FORUM IS DEAD!!!!!!!
JBM  
#5 Posted : Thursday, November 13, 2008 7:50:07 PM(UTC)
JBM

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I had not disconnected the wires from the H-Element, when I do it measures 65 ohms +, which would tell me it is fine.

I heated the thermostat and it did close when heated, but like you say you don't know at what temperature.

I am going to by pass the thermostat to see if the element heats at least and if the unit cycles - otherwise I am at a loss - I have two timers which are probably good - but I can't tell for sure and I don't have any clue as to what to try next?
JBM  
#6 Posted : Wednesday, November 19, 2008 6:50:48 PM(UTC)
JBM

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I have bypassed the Thermostat (temperature regulator - formal part name) and the Regular cycle completes.
I have read on a number of threads the culprit has been known to be the Selector Switch. I have cleaned the contacts/ and tested the Selector switch assembly and have found continuity across 1-2 & 3-4.
The heating element still has resistance reading of 11 ohms.
Having already replaced the timer, (2) High limit Thermostats as well as the Thermostat - short of replacing the Heating element, which I have to believe is good - I am at a loss as to what I can even try next to get the Heating element to heat?

While I can run the dishwasher through all cycles with the thermostat shorted - the water temperature is no hotter than the hot water entering - I am fresh out of ideas or options???
Help is appreciated.
Thanks,
rennman  
#7 Posted : Friday, April 24, 2009 6:24:02 AM(UTC)
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Hi JBM...
I am working on the same dishwasher with exactly the same problem. I replaced the low temp thermo-disc as well as the entire heater assembly.
But the same problem is still there... water heater elements never turn on... even when thermo-disc connections are jumpered (to have clock motor complete the wash cycle). Did anybody ever get back to you with the correct solution to this truly elusive problem? I spoke to Bosch support, but the people that man the phones are not very technical. You would have to talk to one of the designers of the machine and that ain't gonna happen.
JBM  
#8 Posted : Sunday, April 26, 2009 1:38:48 PM(UTC)
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Hi Rennman, I never did get a reply - so I have jumpered the thermostats and it seems to work fine, with the exception of the drying cycle.
We will be replacing it soon, given it is around 15 years old so I am just postponing it for as long as I can.

Let me know if you get this issue resolved.
JBM
rennman  
#9 Posted : Sunday, April 26, 2009 5:49:52 PM(UTC)
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Interesting that nobody (not even Bosch phone tech support) can tell you what causes this common problem on this purely electro-mechanical machine (no micro-processors, no circuit boards, no digital stuff at all). I guess the only one who knows the answer is the German engineer who designed this dishwasher and even then I'm not so sure. But isn't there anybody out there in forum-land who has solved this one. I find it hard to believe that there's no one. Thanks for answering JBM.
JBM  
#10 Posted : Sunday, April 26, 2009 6:40:41 PM(UTC)
JBM

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Hi Rennman, Gene at the start of the thread was the most helpful and directed me to the schematic which I used to troubleshoot the circuitry.
Otherwise I am in total agreement with you - having changed all the parts to no avail.
Take care,
Blake
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