Wednesday, December 10, 2014

EcoQuest Fresh Air II air purifier repair

I have purchased some junk EcoQuest Fresh Air air purifiers to repair.  I fixed one by replacing the capacitors in the power supply.  I like these air purifiers because they feature an Ozone maker, and Ionizer a UV light (to kill germs) and a normal air filter too!

I have two of these air purifiers that I cannot fix.  They come in two versions.  Version one has a 12 volt switching power supply in the lower left corner.  Then there are three Triacs in the middle that turn power on to the devices.  Then there is a 5 volt regulator over on the right side that powers the logic circuits.  On mine the IC for the 12 volt power supply blew up.  I tried taking a 12 volt AC adapter and powering it up that way.  The green LED comes on indicating that the 5 volt power supply is working.  However the LCD powers up but remains blank.

I labeled the parts in this picture.


My other air purifier is a version two device.  It uses a telephone cord or a SATA cable to connect the LCD Display.  The power supply in the front left corner only puts out about 2 volts and gets very hot. In this model the switching power supply makes 8 VDC, 12 VDC and 40 VDC.  The test points for these are located just above the power supply transformer that is covered in metal in the picture below.

This is a close up showing the power supply test points.

Once again I used an AC adapter to provide 12 volts and 8 volts but it would not power up even then.  However the AC adapter was not loaded down indicating that the switching power supply is at fault.

Does anyone have schematics or anything that would help me in fixing these?

12 comments:

Nikolay Kashirskiy said...

I have this board and some problem too. My version of board is second 21-41011-009.
My power input part is fully destroyed after overvoltage and i need you help.
I am need nominal of resistor R38, maybe you can measure this nominal for me?
After repair this part, i can redraw power input part and measure some points for you.
Sorry for my bad english.

Bob Davis said...

Nikolay,
The air filters are someplace in my shed, I will have to dig them out. I will get back to you as soon as I find them. -Bob

Bob Davis said...

Nikolay - The value of R38 is 3.9K.

Nikolay Kashirskiy said...

Thank you very much.
With this nominal of resistor i know oscillator frequency, it is ~100 kHz.
I will try to repair this power supply on this week.
I give you name my broken parts and input schematics, if will be all good.

Nikolay Kashirskiy said...

I send you a part of schematic by e-mail.

Unknown said...

I just opened mine after years of not working.. nothing will come on when plugged in and the fuse is ok. I have the second gen board. I will try to test the voltage points tomorrow.. any other advise one troubleshooting this crazy thing??

Nikolay Kashirskiy said...

I repare my board, it work!
But i replaced all elements of power input part. The total price of all elements ~15$.
As first step, you must check voltage on input capacitor, must be around 175V.
The second step, you must replace viper53 and check all elements around this IC.
If this not help, you can check output diodes and capasitors. My output capacitors is dead too, but diodes is good.

Андрей Плотников said...

Plese help, need nominal r36, r37.

Андрей Плотников said...

Plese help, need nominal r36, r37.

Nikolay Kashirskiy said...

It is very similar piece of schemes:
http://u.dianyuan.com/bbs/u/82/92371255428060.jpg
r36 - 5.1 Ohm
r37 - 10 Ohm

Chris Katko said...

You ever get this thing working? I've got one. The OZ TRIAC is corroded out, and I've got a filter cap near the red flyback that blew. Also, there was a lot of green corrosion which completely killed two traces to the south of that red flyback.

It was "repaired" at some point according to a sticker. But the guy who did it must have been a moron because there were plenty of ugly and even cold-looking, spherical solder joints. I think the cap had a solder joint fail and eventually arc'd itself to death.

Maybe I'm missing something, but it seems dumb as heck to leave the PCB "open to the elements" in an air purifier. Some components may need diagnosing / replacement (so maybe no to potting the whole thing in black goop), but surely letting any water and grime just drop all over the thing.

Bonnie Kramer said...

Hi Bob, Do you have a wiring diagram for Eco quest Fresh Air? when I took off front cover to clean.. a screw dropped out. As far as I can see, it is to the red wire. I don't know where it connects to. Thanks for any help!