- This topic has 25 replies, 5 voices, and was last updated 20 years, 3 months ago by
.
-
Posts
-
Re: Whirlpool Main Control Board
hotshot wrote: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.
I think dented porsche sussed this in his last post 😉
Greg
Re: Whirlpool Main Control Board
hotshot wrote: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.
It can’t, the relay is a part of the PCB in theory.
Whirlpool, and most other major manufacturers do not support component level repairs, in this case if the relay is faulty you would not be able to buy it from them, only the PCB as a whole.
But, as we all know, there are other sources 😉
Dave.
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
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
Hi Hotshot,
I doubt that we would have that sort of information as the Whirlpool guys have a plug in device that can detect the fault. And, even if they did, they couldn’t give you it for the reasons previously stated.
K.
Re: Whirlpool Main Control Board
For future reader’s benefit, live testing of this type is not recommended and can be very dangerous :zap:
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 😉
Dave.
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?
To be honest the plug-in thingybob for Whirlpool agents, not employees, didn’t look that great to me. 😕
Many manufacturers are making it “difficult” for us as well as the public to repair their appliances by using the electronics and fault codes but failing to tell anyone what they mean. If you browse these forums you’ll find loads of examples of this, largely from the likes of Indesit. And if we in the trade can’t get the info and/or tools to diagnose the fault then I’m sure you can imagine what your chances are. 😉
I’d have to say though that it sounds like a PCB failure is quite likely and not exactly unheard of on that range of appliances either. 😉
K.
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
It’s gone out of tollerence then which is the normal problem with the NTC, for some strange reason it doesn’t always produce an error code.
I’m 90{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} certain replacing it will do the trick 😉
Part number 481228268051, which you can get from here:
http://shop.ukwhitegoods.co.uk/product_ … cts_id=476
Dave.
- You must be logged in to reply to this topic.