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Re: Creda T601CW tumble dryer not heating
Thanks iadom, the safety stat had indeed cut out. New part ordered. Cheers.
Re: Creda T601CW tumble dryer not heating
iadom, the hyperlink you gave shows a replacement thermostat. How can I be sure that it is that component that has failed? Is there anything I can test to verify this? Also, could you tell me where this part is located in the machine and how to get at it (e.g. from front or back or machine; if from back, do I have to take off the whole back panel or just part of it?). Cheers.
Re: Whirlpool ADG7540 Tripping Main RCD
Well I managed to get hold of a Megger today and it shows 200Mohm from each terminal of the heating element to earth. That seems to eliminate an earth leak, but could it be that it only fails when hot?
While I had the machine out I think I spotted a very small puncture in the short section of rubber hose that connects to the non-heater element end of the motor/pump assembly. There is also evidence of water collecting on the upperside of the bottom panel (i.e. the panel you have to remove to inspect everything at the bottom of the machine). This may be a red herring as there is no evidence that leaking water has come into contact with any electrical equipment. It also doesn’t fit with fact that the machine is OK on a cold cycle but trips the RCD on a hot cycle.
Re: Whirlpool Main Control Board
I’m happy to report that the problem appears to be fixed after replacing the NTC temperature sensor. Thanks to everybody that helped.
Re: Whirlpool Main Control Board
Dave_Conway wrote:And to try and encourage hotshot not to do it, the NTC should read at 58.1K at 20C, all checks can be done with the power off 😉
Just measured the resistance across the NTC cable at the circuit board end when cable is disconnected (and power off!) – 18k ohms at room temperature. That’s only a third of what Dave quoted. But is that an expected failure mode? I would have thought going open-circuit was more likely.
Even if I suppose the thermistor is duff, this doesn’t explain why the heater has worked on a few occasions recently.
I did try leaving the NTC cable off and starting the programme. Circuit board beeps and a light flashes (as suggested by an earlier poster).
Re: Whirlpool Main Control Board
That’s an interesting point you raise kwatt about Whirlpool guys having a plug in device for fault diagnosis. Are you talking about people employed by Whirlpool? The repair guy who looked at my machine was not from Whirlpool – I got him through Yellow Pages and he didn’t have a plug in tool. He just tested the continuity of the heater and thermistor. In each case this was done underneath the machine at the terminals of the respective component. Having found that the continuity so measured was OK, he concluded that the main control board was faulty (that’ll be £200 thank you very much). He didn’t even look at the main control board and so ignored the possibility of a dodgy connector.
Do some “independent” repair firms use the plug in devices too? Is this a factor to be considered when choosing a repairer?
Re: Whirlpool Main Control Board
By the way, I’m still seeing no error indications. Some people have suggested that if the thermistor is faulty, this would be detected by the main control board at the start of the programme and cause it to abort and show an error. I’m not seeing that.
Re: Whirlpool Main Control Board
Took the heater relay off the PCB and tested it – seemed fine. Soldered it back and added wires to enable monitoring of coil voltage. Reassembled everything. Ran a programme. Water heated correctly during cycle. Coil voltage turning on and off as expected.
A short while later I started a new programme (same temperature). Water NOT heated and no voltage across relay coil at any time! Third attempt a few hours later (after power off / reset) gave same result. That’s the third time that the thing has worked once after being tinkered with, but then gone back to not working. Seems to indicate some form of dodgy connection.
I’m beginning to think it might be the thermostat/thermistor/NTC rather than the heater. Can anyone tell me what the normal voltage across the NTC terminals should be and how this should vary during a cycle? I guess that if the thermistor goes open-circuit, the PCB interprets this as a high temperature and therefore keeps the heater off (i.e. fails safe).
Re: Whirlpool Main Control Board
I have taken the module out and examined it. It does look like the HEW is the output to the heater. This output comes from directly from the contacts of a relay in the module. I have checked the continuity at the relay terminals (with the heater lead connected) and it is fine. I suspect the relay is faulty, i.e. it is failing to switch correctly (most of the time). There is a suspicious rattling noise from the vicinity of the relay when you shake the module.
By the way, I don’t see how the module can detect a faulty relay because there are no current sensing components between the relay terminals and the edge connector of the module.
Re: Whirlpool Main Control Board
Thanks for you help so far. I realise that there are limits on what you can say.
Faulty NTC was Dave_Conway’s suggestion. Not sure myself, as that is not one of the connectors I wiggled last night to get things working again (I think it was HEW, MS and DS).
I don’t get any beeping when selecting a programme and closing the door. The programme starts up and runs through as normal – only problem is water is cold at all times!
Re: Whirlpool Main Control Board
Cool :). Do you happen to know what the “normal” voltage across the NTC would be? Presumably it should change as the water heats up.
Anyone know what any of these stand for?
HEW
MS
DS
WI
SPM
DPM
WV1
DDDR
WV2
NTC (Negative Temperature Co-efficient Thermistor)
FMRe: Whirlpool Main Control Board
Can anyone tell me what NTC stands for (and also any of the other acronyms listed in my original post)? Thanks.
Re: Whirlpool Main Control Board
Can’t say I’ve noticed lamps flashing or an audible beep. It is an integrated appliance, so the lamps are not visible when the door is closed, but I think I would have noticed when I opened the door to check if the water was hot. Will check again tonight.
Does the control board have diagnostics to detect that no current is flowing to the heater? Is that why you are asking if there are flashing lamps?
The washing cycle does not abort, it just runs through as normal – except that the water is not hot.
After it ran cold last night, I waggled a few control board connectors and it worked OK again after that. I suspect a dodgy connection somewhere. May be one of the connectors or perhaps a dry joint or broken track on the control board which is affected by waggling the connectors. This is why I was looking for info about the connector marking codes, so that I can focus on the ones to do with heating (e.g. heater, thermostat).
