Digicabi dry cabinet

[one eye jack]

My DB-036 digicabi bought in 2019 May just stop working. I remove the "PSU" casing to check if its dead, and it really is dead.

The fuse is blown, all capacitors, polyester and electrolytic are out of spec. The bigger yellow polyester at AC side should be 0.1uf/275VAC but measure using 100Hz frequency is 2.2nf@few KΩ! the DC side electrolytic is 100uf/16v is way out also, so as the 104J100 0.1uf/100V polyester at ~2.2nf. I replaced all of them but still the PSU didn't work. To make sure it was just the power unit side, I use a 12V AC/DC adapter with another power module with potentiometer to step down as the stock converter stated 3.6V, a PITA to find a repalcement. Fortunately, the dehumidifier unit still work.

As you can see, my model has shrink the larger SMPS to a cost saving AC/DC converter module. All other components around it were used for safety and smoothing only. As I'm gonna keep thing simple by finding a converter module replacement but the exact same model is >$33 from Aliexpress + shipping! I guess its because 3.6V is non standard voltage as other 3.3v/5v/9v/12v module is only a fraction of the cost at ~$5 a piece. I suppose 3.3V should work since it would be less than 10% lower than 3.6V. https://www.aliexpress.com/item/4001182824992.html

Problem is this module dimension is bigger and the pin spacing isn't a match on the stock. the pin is only 5mm long, unlike capacitor where I can bend the long legs to fit in the thru holes.

Like to ask for expert opinions, use wires to connect the pin to thru holes?

Good work on the self repair. You have 2 ways to connect your power supply.

1. Since pins are only 5mm it is meant to be a direct replacement for PCB. Quick and dirty way is to solder extension solid core wire. You can strip the pvc sleeve , use a sufficient length to be able to curl the wire to existing wire and solder.Yes there will be a ball of solder but since the pins are far apart it is safe. Now you can like normal insert the wires and trim or cut after soldering. Of course it will not sit totally flat on the PCB . Note this is if all 4 pins do not match up or you may have 2 pins that match. Modify accordingly.

2. Use extension wire again with sleeving but strip the part going into pcb. Turn upside down with pins in the air like a dead bug and connect and solder.. You can use glue or double sided tape preferably with some thickness/ foam backing to get good adhesion.

PS: I think you can use a cheap switch mode 5V supply as most have adjustable output that can adjust down to 3.6V. If not a 5 V supply can work but probably need to adjust the voltage going into the dehumidifier or peltier device as it is called. Just get a 5V supply that can put out day 300ma. of current like the guy who repaired his unit above.

 

[limcc]

Good work on the self repair. You have 2 ways to connect your power supply.

1. Since pins are only 5mm it is meant to be a direct replacement for PCB. Quick and dirty way is to solder extension solid core wire. You can strip the pvc sleeve , use a sufficient length to be able to curl the wire to existing wire and solder.Yes there will be a ball of solder but since the pins are far apart it is safe. Now you can like normal insert the wires and trim or cut after soldering. Of course it will not sit totally flat on the PCB . Note this is if all 4 pins do not match up or you may have 2 pins that match. Modify accordingly.

2. Use extension wire again with sleeving but strip the part going into pcb. Turn upside down with pins in the air like a dead bug and connect and solder.. You can use glue or double sided tape preferably with some thickness/ foam backing to get good adhesion.

PS: I think you can use a cheap switch mode 5V supply as most have adjustable output that can adjust down to 3.6V. If not a 5 V supply can work but probably need to adjust the voltage going into the dehumidifier or peltier device as it is called. Just get a 5V supply that can put out day 300ma. of current like the guy who repaired his unit above.

Thanks for the replied. I guess wire extension is the only way or I drill holes and connect traces on the back.

As for the adapter, I don't think I would use 5V as its ~40% overvoltage, The stock converter stated 3.6V and 6W max output, The previous user might have use wrong voltage and underpower unit --5V/0.7A = 3.5W--so the cabinet fail again after a while.

 

[one eye jack]

Thanks for the replied. I guess wire extension is the only way or I drill holes and connect traces on the back.

As for the adapter, I don't think I would use 5V as its ~40% overvoltage, The stock converter stated 3.6V and 6W max output, The previous user might have use wrong voltage and underpower unit --5V/0.7A = 3.5W--so the cabinet fail again after a while.

Yes you may be right about the required current to power the whole circuit. If you have the drilling tools to drill new holes then this is yet another way.

 

[limcc]

Yeah, I think more ampere should provide more power to the peltier unit to bring down the RH level faster. With my current 12V/2A adapter + buck converter with potentiometer, the case has brought down the RH level from 79% to 46% after ~20Hours@1 O'clock, and stay there. Anyway, many digi-cabi user experienced the same PSU failure as us:

Repair of Digi-Cabi dry cabinet and made 2 shocking discoveries

Introduction Avid photographers (or wine lovers) will definitely owns 1 or more dry cabinet to keep their beloved gears in clean condition, and these items are not the longest lasting electronics. …

witonosfreestyle.wordpress.com

"IGNORE" Some said the peltier can be powered up to 6V! So I guess 5V isn't an big issue. "IGNORE"

Edited:
I spoke too fast! With potentiometer adjusted to 5v, the Drycab goes haywire with all the LCD number/logo lited! Now testing 3.3V...

 

[one eye jack]

Yeah, I think more ampere should provide more power to the peltier unit to bring down the RH level faster. With my current 12V/2A adapter + buck converter with potentiometer, the case has brought down the RH level from 79% to 46% after ~20Hours@1 O'clock, and stay there. Anyway, many digi-cabi user experienced the same PSU failure as us:

Repair of Digi-Cabi dry cabinet and made 2 shocking discoveries

Introduction Avid photographers (or wine lovers) will definitely owns 1 or more dry cabinet to keep their beloved gears in clean condition, and these items are not the longest lasting electronics. …

witonosfreestyle.wordpress.com

"IGNORE" Some said the peltier can be powered up to 6V! So I guess 5V isn't an big issue. "IGNORE"

Edited:
I spoke too fast! With potentiometer adjusted to 5v, the Drycab goes haywire with all the LCD number/logo lited! Now testing 3.3V...

I am surprised you used 12V 2A supply but if you can adjust it to required voltage it's ok.
When I said you could use a 5V supply that can be adjusted to the required voltage which is 3.6V at 6 watts as seen from the photo . The rated current approximated to 1.66 watts from calculating W divided by voltage.

How to Calculate Amps, Volts, and Watts

Learn how to convert different wattages with one simple formula! Or, use our handy calculator to convert amps, watts, and volts easily!

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You have misunderstood my post and powered circuit with 5 volts.

You can check the specs of a peltier unit from its datasheet. Now for clarity about this particular power supply as stated 3.6V at 6 W means it can output 3.6V up to 6W. So in general the actual circuit should be less than the raring in terms of power at 3.6V or else the power supply cannot take the load current.

 

[limcc]

I see, I never took out the inside unit since changing PSU works, so I don't know the peltier spec.

I want to keep PSU spec at least equal to stock cause we all know, they will use as low power as they can get to save cost. I use watt meter to check the current and wattage used when the unit is running. I opened the door for a while to bring up the RH to 56% to check. The watt meter show 0.031~0.041A with power factor at a miserable ~0.3. So the actual wattage drawn is about 3W when running.

I probably skip the power module and goes with 3.6V AC/DC power adapter.

Universal-Netzteil 6,5 V 3,6 Volt Transformator 3,3 V 3,5 V 3,6 V AC DC 5 V 6 V 6,5 V 3 A Netzteil 6 V Adapter EU US UK AU Stecker - AliExpress 13

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

drill a hole and attach the barrel socket on the back

https://shopee.sg/FSFO_5-Pair-DC-12V-Male-Female-Socket-Panel-Mount-Barrel-Jack-Plug-Power-Connector-i.579411289.19138724987

 

[one eye jack]

I see, I never took out the inside unit since changing PSU works, so I don't know the peltier spec.

I want to keep PSU spec at least equal to stock cause we all know, they will use as low power as they can get to save cost. I use watt meter to check the current and wattage used when the unit is running. I opened the door for a while to bring up the RH to 56% to check. The watt meter show 0.031~0.041A with power factor at a miserable ~0.3. So the actual wattage drawn is about 3W when running.

I probably skip the power module and goes with 3.6V AC/DC power adapter.

Universal-Netzteil 6,5 V 3,6 Volt Transformator 3,3 V 3,5 V 3,6 V AC DC 5 V 6 V 6,5 V 3 A Netzteil 6 V Adapter EU US UK AU Stecker - AliExpress 13

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

drill a hole and attach the barrel socket on the back

https://shopee.sg/FSFO_5-Pair-DC-12V-Male-Female-Socket-Panel-Mount-Barrel-Jack-Plug-Power-Connector-i.579411289.19138724987

You are the boss , go ahead and report back the result.

 

[limcc]

Just to report back, the 3.6V AD/DC adapter works.

As I stated, I drilled a hole on the plastic panel and attached the barrel socket, solder the wire to the stock PCB DC side so I can make use of the exiting electrolytic cap and safety cap, probably not needed as any voltage/current surge--like what happened that cause the stock power module to die, together with the surrounding components--would kill the 3.6V adapter first. But its easier to find and replace the adapter than the internal parts.

The adapter was $12.43 inc/shipping, the barrel socket was $2 for 5 pairs, the caps are 20~30cents a piece. so less than $20 to revive the dehumidifier or half the price of direct replacement of the power module: https://www.aliexpress.com/item/1005007285549964.html

The exact model is WA6-220S3V6D3

If you have TaoBao account, exclude shipping, it would be a lot cheaper than Aliexpress. I had tested with 3.3V, no issue running for few days, I believe 3~4V should be safe. So you don't have to stick with 3.6V, model from other manufacturer should work. But as stated, the pin spacing can be a problem.

Still, I would recommend the external AC/DC adpater + barrel socket.

 

[one eye jack]

Good job. You have helped others with your idea. Thank you. Happy new year.

 

[Sausage]

I was wondering, can I connect the power output from the 5v 700mA power board directly to the peltier? Is it necessary to pass the power through the board with a transistor and potentiometer?

Because my potentiometer board is faulty.

 

[one eye jack]

I was wondering, can I connect the power output from the 5v 700mA power board directly to the peltier? Is it necessary to pass the power through the board with a transistor and potentiometer?

Because my potentiometer board is faulty.

No you cannot connect directly power supply because the peltier controller board regulates the voltage to it and perhaps monitor the voltage or current. Also note that in my photo I listed peltier unit gets negative 2 volts ( measured voltage ) I can't remember now but it's best to check datasheet of similar one to see what voltage it operates with.

Like @limcc he attach new external power supply to the supply connector of the controller PCB. Whether you want to copy his implementation is your choice or reuse the connector cable to adapt to your new supply.
For reference please read his post above.

There are no capacitors on controller board but the transistors may be bad but as @limcc said the controller PCB is functional.

Note that later dry cabinets use only one board all in one so unless your have electronic knowledge and can trace what goes where then the only recourse is to find a peltier board replacement .

Other than buying a new dry cabinets as a stop gap just put in 1 or 2 moisture absorbers like Hungry Hippo or ntuc equivalent but these are larger in height. This is what I did but because my equipment are all 2nd. hand I don't mind .I also used IKEA airtight food containers of 2 sizes but can only use hungry hippo because ntuc generic ones are higher so cannot close the cover or lid. For dry cabinets it is useful to put a stand alone hygrometer to monitor humidity. You have to test whether 1 or 2 absorbers is sufficient. For a small 36L cab I use 2 but humidity goes way below recommended percentage but to me It's reassuring but people warn that rubber might crack but my equipment is all 2nd. hand. If the absorbers are filled with water then it's time to replace hence the hygrometer to confirm.

 

[Sausage]

ok, I got another potentiometer board and I ruined it again.
Same thing.
I'm using the aliexpress 5v 700mA power supply board, and i connected it to the potentiometer board. That board lights up with both red and green LEDs and the peltier gets nice and cold. So it worked for 2 days and died again. The pot setting was in the middle range.

Powered down, opened up and checked again after power on. The red power led on the power board and potentiometer board both light up. But the green LED will not light up anymore regardless of the potentiometer setting, and the peltier doesn't get cold.

No idea what's wrong, since it seems power is being delivered. This is the 2nd time this has happened.

 

[one eye jack]

ok, I got another potentiometer board and I ruined it again.
Same thing.
I'm using the aliexpress 5v 700mA power supply board, and i connected it to the potentiometer board. That board lights up with both red and green LEDs and the peltier gets nice and cold. So it worked for 2 days and died again. The pot setting was in the middle range.

Powered down, opened up and checked again after power on. The red power led on the power board and potentiometer board both light up. But the green LED will not light up anymore regardless of the potentiometer setting, and the peltier doesn't get cold.

No idea what's wrong, since it seems power is being delivered. This is the 2nd time this has happened.

Someone on his thread pointed out that the power required is somewhere around 1.5A to 2A so get a higher capacity power supply. Sorry for late reply as this forum was technically inaccessible until now.