Jet AFS-1000B Air Cleaner

[elmo]

I have a Jet AFS-1000B Air Cleaner. It has a three speed blower and a remote control. It has a CP8112B-L8SN24 controller and BT139X-600F triacs on the output to the blower. I usually run it on the lowest speed. Recently, it started shutting off after running for only a few minutes. If I restart it immediately, it will run for only a few seconds. If I wait a while, it will run for a few minutes again before shutting off. Could a failing triac cause it to operate this way? The remote control and all the speed and timer functions seem to work fine. The control board is powered up all the time even when the blower is off.

[stj]

Re: Jet AFS-1000B Air Cleaner

got some pcb foto's??

[fzabkar]

Re: Jet AFS-1000B Air Cleaner

Is there a thermal cutout?

Here is the datasheet and application circuit for the controller (CP8112B-L8SN24):

http://pdf.icpdf.com/download.asp?id=1650964_201185

[fzabkar]

Re: Jet AFS-1000B Air Cleaner

JET AFS-1000B Operating Instructions:

6.2 Overload protection

The fuse switch (C, Fig 4) will pop out in case of overload. Wait 5 minutes and push the fuse back in.

[elmo]

Re: Jet AFS-1000B Air Cleaner

Thanks for all your responses. I don't have any photos yet but will post them as soon as I do. There is a thermal overload switch on the unit but it is not tripping. I did find a data sheet and circuit diagram for the controller IC but it may not be the same one you are referring to. The one I have is at .

I found someone on another forum who was having the same problem. He solved his by replacing the whole circuit board. I was hoping to be able to repair the one I have since it seems to be in good shape. I think the controller IC is working since I can select all the different speeds and times with the remote control. That is why I thought the triac might be failing. I haven't been able to check the -5V supply yet but it seems to be adequate to power the controller IC and the remote control.

[fzabkar]

Re: Jet AFS-1000B Air Cleaner

The externally resettable overload switch is most likely a current overload. The motor probably has an additional thermal cutout embedded within it.

I would remove the PCB and connect the motor directly to AC using each of the L,M,S windings in turn. It would be advisable to include the external current overload switch in the circuit.

[elmo]

Re: Jet AFS-1000B Air Cleaner

Sorry to be gone for so long. I have not had much time to work on it due to other pressing problems. I did manage to remove the control board and jumper the motor directly to power. It works fine in this mode so I'm thinking the problem is in the board.

[kaboom]

Re: Jet AFS-1000B Air Cleaner

Could a failing triac cause it to operate this way?

Yes.

Sorry to be gone for so long. I have not had much time to work on it due to other pressing problems. I did manage to remove the control board and jumper the motor directly to power. It works fine in this mode so I'm thinking the problem is in the board.

Half shorted or leaky triacs will impose a DC component to the voltage fed to the motor.

An induction motor such as the one you're dealing with will not tolerate this. The stator will saturate- motor draws excessive current and pops the breaker/overload.

[elmo]

Re: Jet AFS-1000B Air Cleaner

Kaboom

Thanks for the suggestion. However, the overload is not tripping. It almost seems as if the controller was getting a shutdown command. But the operation is not random. It is very consistent.

[budm]

Re: Jet AFS-1000B Air Cleaner

Still no pictures of the boards?

[elmo]

Re: Jet AFS-1000B Air Cleaner

Sorry about the photos. I thought I had uploaded then earlier.

[kaboom]

Re: Jet AFS-1000B Air Cleaner

If C3 is bad/fake/questionable, the micro gets bad power and resets- unit appears to then be "off," since powerup state for micro is to default to fan off.

This is a capacitive divider power supply- C2, 2.2u (10%) if decreased in value will cause strange symptoms- things like micro dropping out upon driving triac gates (for instance).

I'm suspecting C3- replace with good 105 degree low esr unit, such as for an SMPS. Extreme ripple into that micro will wipe its programming, seen this with cheep "tower" fans and crock pots. Use PW, HE, FR, FC, or equivalent.

[stj]

Re: Jet AFS-1000B Air Cleaner

the original soldering is a joke, most of it is only touching the pins and not binding to them.
it almost looks like they used the wrong type of flux on the production line.
specially the large connector.

[Longbow]

Re: Jet AFS-1000B Air Cleaner

Half shorted or leaky triacs will impose a DC component to the voltage fed to the motor. An induction motor such as the one you're dealing with will not tolerate this. The stator will saturate- motor draws excessive current and pops the breaker/overload.

Since triacs are used in AC circuits, I can't see how a bad one would impose a DC component to the load. If the triac becomes shorted, your motor runs all the time. If the triac has turned into a resistor, then the motor gets lower AC voltage than it is used to. The motor might not start or may get hot, but the triac will get even hotter. So far, no evidence of thermal problems. The controller would be the next best choice.

[budm]

Re: Jet AFS-1000B Air Cleaner

Do you have the pictures of the blower motor?

[budm]

Re: Jet AFS-1000B Air Cleaner

Is this the blower motor?
http://www.ereplacementparts.com/motor-p-446851.html
It has AC caps for the motor.

[kaboom]

Re: Jet AFS-1000B Air Cleaner

That's a multispeed PSC motor- exactly the same as a common furnace blower motor. Four wires=three speed taps, plus neutral/common.

If more than one tap is energized at the same time, you get smoke and a dead motor.

[elmo]

Re: Jet AFS-1000B Air Cleaner

Thank you all for your suggestions. I can't see the motor, but I presume that is the correct one since it is the replacement part for the AFS-1000B. I think the motor is all right since I ran it for over an hour with the board jumpered out. I just measured the -5V power supply voltage. It does indeed measure 5 volts with about 60 mV of ripple. Of course this is with no load on the board. This may not be surprising since the blower always ran when started. It just does not run for long when powered by the board. I, too, am suspicious of C3 since the top of it is bulged out somewhat. I guess the only thing to do is to replace it and see if that helps. It seems that most of you think Panasonic makes good capacitors but are not Nichicon, Rubycon, Kemet,ans Vishay good brands too?

[Longbow]

Re: Jet AFS-1000B Air Cleaner

Other possibilities, taking into consideration all of your observations: the 32 KHz clock crystal used in this circuit is a type widely used in lots of gear. If possible, check the waveform on the osc pins, or if test equipment is unavailable replace it next time you place a parts order (they are very easy to find and inexpensive). Also check the resistor on pin 2 of the controller. This resistor sends zero crossing information to the controller, and it may have changed value. That would upset the firing on the triacs.

As mentioned before, the soldering on your board is terrible. Heat and vibration will create miniature cracks that can hardly be seen. I would run small tinned bus wire along any of the AC traces starting with the board AC connector pins. The points where the connector pins solder to their traces are of special interest. Same goes for the legs of the triacs.

[kc8adu]

Re: Jet AFS-1000B Air Cleaner

half a triac equals a diode.

Since triacs are used in AC circuits, I can't see how a bad one would impose a DC component to the load. If the triac becomes shorted, your motor runs all the time. If the triac has turned into a resistor, then the motor gets lower AC voltage than it is used to. The motor might not start or may get hot, but the triac will get even hotter. So far, no evidence of thermal problems. The controller would be the next best choice.