Dimplex DH212 Dehumidifier - Compressor Not Starting

[mcquaim]

Hi guys,

Thanks for the updates.

I think I will try to replace the resistor first and then try the relay.

I can't find an exact match for that resistor anywhere online. I was searching for 47 ohm 5% Tolerance 5 colour band resistor?

Any help would be greatly appreciated...

Cheers,
Mac

 

[Les Jones]

This 47 ohm resistor is not a normal resistor. It is a fusible resistor that acts as fuse. If the 1 uF capacitor failed short circuit it would cause this resistor to fail. (The fusible resistors that have failed due to overcurrent have normally had visible overheating so it is possible that just this resistor has failed.) As a precaution I suggest checking that the 1 uF capacitor has not failed short circuit. Farnell stock them under this stock code 1738544
You may also find a suitable one on ebay. For safety reasons DO NOT USE A NORMAL RESISTOR.

Les.

 

[mcquaim]

This 47 ohm resistor is not a normal resistor. It is a fusible resistor that acts as fuse. If the 1 uF capacitor failed short circuit it would cause this resistor to fail. (The fusible resistors that have failed due to overcurrent have normally had visible overheating so it is possible that just this resistor has failed.) As a precaution I suggest checking that the 1 uF capacitor has not failed short circuit. Farnell stock them under this stock code 1738544
You may also find a suitable one on ebay. For safety reasons DO NOT USE A NORMAL RESISTOR.

Les.

Hi Les,

Thanks for the reply and for the link for the resistor. Do you think this will work ok even they look slightly different?

Also, you suggested testing the capacitor. Should I text all 3 of them?

Perhaps I need to test other components also or is it worth just buying that resistor, putting it in and seeing if it solves the issue?

Cheers,
Mac

 

[Les Jones]

I think that fusible resistor should work. (The picture an Farnell's web page shows a different value resistor to a 47 ohm one. It is just to give an idea of the style of the resistor.) It is worth spending a few seconds checking that the 1 uf capacitor is not short circuit. There is also a varistor on the board that connects between the output side of the 47 ohm resistor and what I think is probably mains neutral. You have not shown us what the other connections on the board are connected to. The only one we can make a good guess about is the mains live input connection. It is also worth checking that this varistor is not short circuit. I only traced the circuit far enough to confirm it was a typical transformer less power supply. It is unlikely that anything after the bridge could cause the resistor to fail. Even if the bridge rectifier failed short circuit the 1 uf capacitor would have a reactance of about 3.3 k ohms. (Assuming 50 hz mains) Even if your mains voltage is 240 volts the current would be limited to about 73 mA.

Les.

 

[sagor1]

While Les may be right, the example he links to is not the same "size". His link is to a 2W type, 10mm long. Your resistor/fuse is almost 15-16mm long based on your picture. That puts it into the 3W class of device. There may be 2W versions this size, but shop carefully.

EDIT: Digikey has a product, SP3AJT47R0, that is a 4W, 47 ohm fusible resistor that is only about 12-13mm long. If that is what you need, that device will do nicely. That said, a 4W fusible resistor may take longer to burn the "fuse", since it is rated at a higher wattage. Confusing, isn't it...

 

[mcquaim]

Hi guys,

Yes, this is getting confusing alright haha..

I placed and order for those resistors that Les suggested but if you guys think it isn't correct I can hopefully change it to something better suited?

It seems quite difficult to find this exact resistor?

I spent all day looking and found no exact matches...

Cheers,
Mac

 

[Les Jones]

I think sagor1 is probably correct. I had just looked at it's physical size without attempting to scale it's size against other components of known size. (The DIL package IC.) What is the mains voltage and frequency in your country ? (You don't even give the country you are located in in your profile.) If we know that we can calculate the likely dissipation in that resistor.

Les.

 

[mcquaim]

I think sagor1 is probably correct. I had just looked at it's physical size without attempting to scale it's size against other components of known size. (The DIL package IC.) What is the mains voltage and frequency in your country ? (You don't even give the country you are located in in your profile.) If we know that we can calculate the likely dissipation in that resistor.

Les.

Hi Les,

Thanks for the reply.

I never noticed that option to specify in my profile when I was registering. I will update that today.

Anyway, I'm in Ireland here so voltage is 240v and frequency is 50Hz.

I will ask Farnel to hold off on my order until I find out more information.

Thanks,
Mac

 

[Nigel Goodwin]

Hi Les,

Thanks for the reply.

I never noticed that option to specify in my profile when I was registering. I will update that today.

Anyway, I'm in Ireland here so voltage is 230v and frequency is 50Hz.

Nothing to do with this thread - but is your mains actually 230V or 240V?.

The EU mains was (supposedly) standardised at 230V - but this is only for equipment manufacture, to ensure equipment works fine across the EU (UK is 240V and the rest 220V). In the past European equipment failed a lot in the UK as it was designed for 220V, and the 240V stressed it.

The 230V 'standard' has two versions - one for the UK which covers 240V, and one for the rest, which covers 220V (they just altered the +/-% allowed) - as far as I'm aware no voltage changes ever took place?, and certainly not in the UK.

 

[mcquaim]

Hi Nigel,

Yes, we are the same here. If you ask the ESB here in Ireland they'll state that it's 230v but the correct value is actually 240v.

Anyway, that's beside the point here I guess...

I asked an electronics company here in Ireland if they stocked the resistor and sent them photos. I don't think it's correct though, missing that last black line?

TE Connectivity 47Ω Carbon Film Resistor 1W ±5% CFR100J47R | RS

ie.rs-online.com

Cheers,
Mac

 

[sagor1]

That link/resistor is not a fusible one, and the wattage (1W) is probably too low. You have to use at least a 2W, possible a 3W "Fusible" resistor if Les is correct about its function. Look at the length/dimensions of your "resistor". The replacement should be about the same, within 1mm. A proper fusible resistor will have that extra black band as well (most likely).
Digikey here in North America (canada anyway) has this one: FKN3WSJT-73-47R which is a 47 ohm, 3W fusible resistor that is 15.5mm long. The key part number is the FKN3WS. That determines a 3W and the 15.5mm length type of resistor

FKN3WSJT-73-47R YAGEO | Resistors | DigiKey

Order today, ships today. FKN3WSJT-73-47R – 47 Ohms ±5% 3W Through Hole Resistor Axial Flame Proof, Fusible, Safety Wirewound from YAGEO. Pricing and Availability on millions of electronic components from Digi-Key Electronics.

www.digikey.ca

 

[mcquaim]

Hi there,

Thanks for that.

I ordered that one off digikey.ie but it's just imported by the looks of it. $22 shipping charge... Still, if it works then still a cheap fix...

Thanks for the link, appreciated.

Cheers,
Mac

 

[Les Jones]

Hi Mac,
Digi-Key have an outlet in the UK https://www.digikey.co.uk/

Les.

 

[Nigel Goodwin]

Hi Mac,
Digi-Key have an outlet in the UK https://www.digikey.co.uk/

Les.

But do they have stock in the UK?, I think that's just a UK link to the America site? - but $22 shipping was a bit crazy - we order from Digikey occasionally, and it's nothing like that.

 

[mcquaim]

But do they have stock in the UK?, I think that's just a UK link to the America site? - but $22 shipping was a bit crazy - we order from Digikey occasionally, and it's nothing like that.

Hi Nigel,

I'm not sure how they work, it doesn't look like they hold stock in Ireland or the UK.

Both times they're charging international shipping and customs charges.

I can't find it anywhere else so $22 will just have to do fine.

Cheers,
Mac

 

[Les Jones]

I've just done an estimate of the power dissipated in the 47 ohm resistor. I will assume you mains voltage is on the high side so call it 250 volts and I will assume all of the 250 volts is dropped across the 1 uF capacitor. The reactance of the 1 uF capacitor at 50 hz is 3183 ohms so the current is 250/3183 = 0.079 amps.
So the power dissipated in the 47 ohm resistor will be 0.079^2 x 47 = 0.00624 x 47 = 0.293 watts. Because of the approximations made in the above calculations the actual dissipation will be very slightly less than the value from this calculation.

Les.

 

[sagor1]

If ordering, order a few. You just don't know if something else is shorted on that board, and a short may blow your replacement resistor before you know it....
There may be other types from different vendors. The key is the "fusible" option, along with a proper power rating (watts) to match what you have before

 

[mcquaim]

Hi folks,

I tested the 1 uF capacitor this morning and it appears to be working fine, charging and discharging ok anyway using the multimeter.

Perhaps it's worth testing the 0.1 uF capacitor that is down the circuit from the live input connection?

I am removing the capacitors from the board to test them, this is required?

Cheers,
Mac

 

[Les Jones]

Can you explain your reasoning for suspecting a problem with the 0.1 uF capacitor ? Can you also post the part of the schematic around that you must have traced out to conclude that is is faulty ? From what information I have seen I can't see any reason to suspect that capacitor.
I have added a mirrored version of the etch side of the board to make it easier to trace the schematic in future.

Les.

 

[mcquaim]

Hi Les,

I was just following your instructions on post #24 to check the capacitor. But, after testing it I can confirm it's working perfectly.

The replacement resistor just arrived so I will install that and check that all is well afterwards...

Thanks,
Mac