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£0.43 Fix for Meaco DD8L Dehumidifier

siman007

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6 Dec 2020
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3

Sheena Carmichael

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7 Dec 2020
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We have taken the Meaco DDL8 apart just about to the same point as you - it is sitting on the kitchen table in pieces at present. Ours (just under 4 years old) just went dead. How did you get the thermistor out without demolishing the Meaco further? But I am not convinced that is our problem because it looks fine (see photo). Any other ideas would be welcomed...
 

Attachments

SaltIre

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13 Mar 2017
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14,986
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None of your nosey business
I found this clip last night, which didn't explain what siman007's part was, but explained that air is blown past it. Not sure if it helps.
Copied from below the video:
A look inside a Meaco DD8L desiccant dehumidifier. (Which is actually a rebadged You Long YL-208A) These dehumidifiers are much quieter than traditional compressor based ones. They work by rotating a drum of honeycombed desiccant material (zeolite) through an airflow from the area to be dehumidified, then through a heated section that drives the collected moisture out into a condensing panel. I managed to fluff twice and suggest that these units are sensitive to being moved. They aren't. Traditional compressor dehumidifiers are sensitive to being moved during or just before use, since the refrigerant liquid can get into the compressor and stall it.
These units can be dragged out the boot of a car and plugged straight in without a settling time. The desiccant units are very lightweight since they do not contain much metal. Another advantage over the compressor versions is that these ones will operate efficiently down to near zero temperatures when there is virtually no moisture in the air anyway. Compressor units are very inefficient at low temperatures. The reason for the air filter on the front of the unit is to prevent particulate from blocking the pores of the desiccant drum. Although these units consume more power than an equivalent compressor unit with a low setting of typically 300W and a high setting of about 600W they don't use any more power overall since they bring the humidity down quickly and then turn off. The output is a stream of noticeably warm and very dry air. These units are not to be confused with the absolutely useless desiccant dehumidifiers that are either a bag of silica gel or a chemical that absorbs moisture and then turns to slush in a plastic tub. The silica gel is OK for very small enclosed containers but not continuous room dehumidification.
Using a dehumidifier in a home prone to dampness like a coastal home or older style of building will solve many problems like mold and excess condensation on walls and windows. The dryer air is more comfortable and greatly reduces the need to heat the building excessively. Even at it's highest setting (about 600W) one of these units can be run continuously for a full day for considerably less than the cost of a cup of coffee from Starbucks. Most of these units have a laundry setting where wet washing can be hung indoors in the same room as the dehumidifier and it will dry it all quickly by removing the moisture from the air. Although many of these units have quite complex electronic controls, I prefer the simpler version with just a high/low switch and a knob to set the desired humidity. Much simpler and potentially more reliable.
 

Lomax

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Joined
22 Sep 2016
Messages
279
Does anybody know what this is (and where I can get another one :cool: Thank you!
You're correct: it's a temperature sensor, either a PTC or an NTC. It's the device on the right in this picture:

fuses_and_thermistor.jpg

The other two devices are 133°C thermal fuses. Both the fuses and the thermistor should be easy to find, and not expensive - the only problem is we do not know the temperature coefficient of the thermistor... If anyone has a disassembled unit available it should be possible to establish by measuring how the resistance changes from room temperature to being immersed in boiling water.
 

Lomax

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Joined
22 Sep 2016
Messages
279
Ok I think I now know what it is - I think its a Glass Shell Precision NTC Thermistor - I measured the resistance on the remains of mine at 20c and got 67k ohm which I think equates to the 50Kohm version which has a part no of MF58503F3950 (MF58503F3950 Cantherm | Sensors, Transducers | DigiKey)
I didn't see this post before replying, but yes, that's it. But you really should check if the resistance increases or decreases with temperature, and ideally what it is at another known temperature. Only then can you be sure if it's a PTC (resistance increases with temperature) or NTC (resistance decreases with temperature) thermistor, and precisely which such device (by checking that your two measurements agree with the curve in the datasheet). Boiling water is a reasonable approximation of 100°C (and if you know the current air pressure it can be quite precise).

Edit: With those two measurements in hand you can very easily calculate the "beta" value of the thermistor:

Beta-300x198.jpg

Where:

Rt1 = Resistance at Temperature 1
Rt2 = Resistance at Temperature 2
T1 = Temperature 1 (K)
T2= Temperature 2 in (K)

Since "beta" is a defining characteristic of thermistors having this value makes selecting the correct one easy.
 
Last edited:

Kernown

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19 Dec 2020
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1
I've had a read through the thread, the problem I have doesn't seem to be mentioned, the main fan won't start on my dd8l. It powers up normally, all the other parts work fine, just the fan doesn't start. The fan spins freely, the capacitor seems fine when tested with a multimeter. So, does anyone know how to test if the fan is getting power, or if the fan it's self is faulty? As an aside, I see the you long name on the fan, can the cheaper you long version of this machine be bought in the UK? Cheers
 

EQB

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16 Jan 2021
Messages
1
Thanks to the helpful instructions here managed to get mine apart and fix the block that was causing water to leak from it so I took some photos that might help, you can see the puncture holes for the four screws. Plus the the extra bit revealing the extra button.
View attachment 82994
There are four screw for the base (Feet) and the the four screws in the water tank housing.
View attachment 82995
Then as has been said before "unclick" down the sides to get the front panel off.
View attachment 82996
This should give you access to the fan and other motors. I needed to get to the other side so had to undo four more screws.
This one just above the blue wire.
View attachment 82998 View attachment 82999 View attachment 83000 View attachment 83001

Now with the other side off
View attachment 83002
This was actually after I had cleaned the "Crud" blocking the tube poking out the bottom.
I had to remove this bit too
View attachment 83003
Here is the blockage
View attachment 83005

Not sure how helpful this is.
My floor is now dry and and it is all working correctly although the top looks a bit off a mess.
hi
I havnt tried this yet but it seems like the best advice yet, thanks
 

redness

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Joined
29 Jan 2021
Messages
1
hello all,

i'm amazed how many members are posting faults with the Meaco DDL8! - and here is another...
my unit has stopped working - switch it on at the plug, the green lights come on momentarily and then revert to the red warning light and blowing only cold air

is anyone familiar with this problem? fixing this problem? Would be such a shame to throw it away after only 9 months use

thank you
 

sarabande

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Joined
6 May 2005
Messages
34,968
Not only a shame, but you should have a 2year warranty to rely on.
 

NM1980

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Joined
29 Jan 2021
Messages
1
Hello,

I too have a Meaco DD8L that is playing up. The red on/off/enter button does not seem to react at all. When I press the left arrow the display lights up and shows my settings. All the other arrows allow me to navigate through settings and change them but the red button just does not do anything. The dehumidifier just refuses to start, yet it still detects high humidity and shows "HI" warning when there is too much moisture in the air. I would appreciate any ideas about what could be done to make it work again or any thoughts on what has gone wrong. I would much rather get this to work again; not too fond of disposing of things that still show some signs of life and might be fixable.
 

jw2021

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Joined
10 Feb 2021
Messages
1
Hi,
in reply to Redness, I had a fault on my DD8L - it would switch on normally, run for about a minute and then stop with the orange warning triangle illuminated.

I tracked this problem down to a faulty fan that blows air over the heating element, I managed to get a replacement part from ebay.
I reckon that with this fan not working the heater quickly overheats, hence causing the machine to shutdown.

I now unfortunately have another fault - not quite so terminal as the previous one though. I now find that I can only get it to run at its 'normal' setting . If I try to run it slower on its lowest power setting it stops after a few minutes. I'm not sure whether this is related to the low temperature it's operating at, at the moment (about 4 degC - its in a workshop). Has anybody any ideas?
 

ppuzniak

New member
Joined
19 Feb 2021
Messages
1
I'm also trying to repair a Meaco DD8L Junior which has gone completely dead (no LEDs, no beeps, no fan or motor action). Mine actually has four melt fuses; I first found two green 133° (SEFUSE SF 129E) attached to the back of the heater element enclosure, but both these measured ok so I kept looking and found two brown 99° (SEFUSE SF 96E) fuses on the other side of the desiccator wheel. I had to totally disassemble the unit to get to these, and was dismayed to find that they were also intact. I now have a big pile of parts and no idea what else to look for. Any ideas?
Hey, did you solved your issues? Did they send you a new PCB?
 

Chopchop

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Joined
10 May 2021
Messages
3
I have now reassembled the dehumidifier, and have done some probing on the control PCB:
  • The 1.6A fuse (circled in red in photo) is intact (I had already measured this before disassembly)
  • I get continuity on the thermal fuse chain, connected between TC1 and TC (confirming yet again that the thermal fuses are indeed intact)
  • The -5V and -12V rails are operating and within tolerance (why negative rails? no idea!)
  • There are no signs of life of any kind, even if leads are wiggled or components tapped
It looks like I might need a new control board, unless anyone has any other suggestions?
Hi lomax,
I and my DD8L are in the same state now, with all the same checks you list above.
What did you do next?
What interlocks are there that may prevent the display panel lighting?
Any help much appreciated, on this excellent forum.
 

nikakis30

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Joined
10 May 2021
Messages
4
I didn't see this post before replying, but yes, that's it. But you really should check if the resistance increases or decreases with temperature, and ideally what it is at another known temperature. Only then can you be sure if it's a PTC (resistance increases with temperature) or NTC (resistance decreases with temperature) thermistor, and precisely which such device (by checking that your two measurements agree with the curve in the datasheet). Boiling water is a reasonable approximation of 100°C (and if you know the current air pressure it can be quite precise).

Edit: With those two measurements in hand you can very easily calculate the "beta" value of the thermistor:

View attachment 104562

Where:

Rt1 = Resistance at Temperature 1
Rt2 = Resistance at Temperature 2
T1 = Temperature 1 (K)
T2= Temperature 2 in (K)

Since "beta" is a defining characteristic of thermistors having this value makes selecting the correct one easy.
I replaced the thermistor with a ntc 50k but the machine is operational only at the low speed fan. Above this the warning light turns on. I think that if the ntc is right must be 100 k if at 25°C the resistance was 67k. Or a ptc of 50 k?
 

Chopchop

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Joined
10 May 2021
Messages
3
I replaced the thermistor with a ntc 50k but the machine is operational only at the low speed fan. Above this the warning light turns on. I think that if the ntc is right must be 100 k if at 25°C the resistance was 67k. Or a ptc of 50 k?
I replaced the thermistor with a ntc 50k but the machine is operational only at the low speed fan. Above this the warning light turns on. I think that if the ntc is right must be 100 k if at 25°C the resistance was 67k. Or a ptc of 50 k?
I could help check if I knew where the thermistors are located. Or I could measure at different ambient temperatures.
My ddl has good thermistors ( 115 k ohms at about 20 degs c. But it is dead at front panel, and I dont know how to confirm dead processor or processor type. Have checked supplies on board.
 

nikakis30

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Joined
10 May 2021
Messages
4
I could help check if I knew where the thermistors are located. Or I could measure at different ambient temperatures.
My ddl has good thermistors ( 115 k ohms at about 20 degs c. But it is dead at front panel, and I dont know how to confirm dead processor or processor type. Have checked supplies on board.
Dear Sir the thermistor is shown clearly at post #105. Now if you touch it with your finger while you measure it the resistance of it must be changing. If it goes upwords is a ptc. If it goes downwards is a ntc.
 

Chopchop

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10 May 2021
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Dear Sir the thermistor is shown clearly at post #105. Now if you touch it with your finger while you measure it the resistance of it must be changing. If it goes upwords is a ptc. If it goes downwards is a ntc.
And now I can offer help to some of those with unresponsive microcontrollers..After some days checking various bits of my DD 8L Junior, I suspected the microcontroller chip. To check, I put oscilloscope lead on crystal to see if clock pulses there, and it burst into life. Now fine, so just the oscillator not running without a little tickle.
The oscillator starts by amplifying ambient noise with poditive feedback.
Hope this may help someone..
 

nikakis30

New member
Joined
10 May 2021
Messages
4
And now I can offer help to some of those with unresponsive microcontrollers..After some days checking various bits of my DD 8L Junior, I suspected the microcontroller chip. To check, I put oscilloscope lead on crystal to see if clock pulses there, and it burst into life. Now fine, so just the oscillator not running without a little tickle.
The oscillator starts by amplifying ambient noise with poditive feedback.
Hope this may help someone..
I made a mistake. The thermistor is shown at post #106.
 
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