WFCO Camper Converter need help understanding KA3846 SMPS Controller

[redwire]

Re: WFCO Camper Converter need help understanding KA3846 SMPS Controller

I believe it's for the 12V cooling fan.

[kiloamp]

Re: WFCO Camper Converter need help understanding KA3846 SMPS Controller

Hi Redwire, thanks for the reply. Good thought but the fan has 2 wires and is plugged in at the other end between the fan and heat sink. You can't see it in the pictures.
The connector in question is at the two 8 pin IC's . I think one is an op-amp and the other a pic maybe. I was thinking maybe there were indicator led's or a mode switch, just guessing.

[kiloamp]

Re: WFCO Camper Converter need help understanding KA3846 SMPS Controller

Well turns out the WF-88XX series is older and discontinued. The 3 pin connector is for a switch to toggle through the different modes. After days of internet searches that's all I found. I guess if the fan came on sooner it would help.
Enough time spent on this, it works now so good enough.

[redwire]

Re: WFCO Camper Converter need help understanding KA3846 SMPS Controller

WFCO's website and photos are shit, I found one pic implying the connector goes to the fan and another showing a front panel 2-pin connector. But the WF-8855E doesn't have anything for controls. I thought the PC board connector might be used for factory calibration where they solder in that selected resistor R50 next to it. Or for programming the MCU.

[kiloamp]

Re: WFCO Camper Converter need help understanding KA3846 SMPS Controller

You could be right Redwire,the connector has one pin to ground, one pin to pin 3 of the pic and one pin to a 330 ohm resistor then to pin 6 of the pic120508A. R50 may be for setting current limit ?, the same board is used for 3 different current outputs. Learned a bit from this board, probably use it to power other projects at the bench for now.

[shadetreetrader11]

Re: WFCO Camper Converter need help understanding KA3846 SMPS Controller

Kiloamp I'm working on the same supply. Is there any way you could take a pic or tell me what the little transistor U6 is. It's the one that's close to the Large Red 12 V output lead is. I'm not able to identify mine. I tried to zoom in on the picture but it gets blurry just about the time I am able to read it. Thanks

[kiloamp]

Re: WFCO Camper Converter need help understanding KA3846 SMPS Controller

Hello Shadetreetrader11, U6 is a KA431az. It's a programmable shunt regulator,
https://www.onsemi.com/pdf/datasheet/ka431-d.pdf
Do you know what CN2 connects to ?

[shadetreetrader11]

Re: WFCO Camper Converter need help understanding KA3846 SMPS Controller

Thank you kiloamp. I don't know exactly what cn2 is. If I had to guess it would be for the use in diagnosing the working of the pic12c508a micro controller. Depending how it's programmed you can hook a special connector on to it and manipulate it to run threw a few of its various tasks. I was reading on wfco's web site trying to figure this out a little bit and they talked about how the power supply will charge at a certain current for a certain about of time and then back off on the current so the battery isn't being over charged. WFCO gives out 0 information on board level repair. Hope this helps.

[kiloamp]

Re: WFCO Camper Converter need help understanding KA3846 SMPS Controller

Your welcome shadetreetrader11. So I'm guessing that CN2 is not connected to anything in the motor home, is just for programing and test ?

[shadetreetrader11]

Re: WFCO Camper Converter need help understanding KA3846 SMPS Controller

That's correct. The connector that the fan for this power supply uses looks almost identical to this connector only difference being it has only two pins on it.