PLX SM-AFR Serial upgrade

[thunder550]

Sounds like it should work.

Here's what I'm planning on doing. I'm using the Null modem adapter because I already have it...bought it to hook up my old LC-1 and it's easier just to reuse it.

I ordered the MAX3232 from ebay yesterday...hoping to have it by the end of the week so I can get this all hooked up and try it out.

[JezzaB]

vxleather tried this the other day and it didnt work. He had to solder into the board in the end.

[vxleather]

Yep the phone jack thing don't work.... As the tip of the pin which we think is the power outlet is actually the signal outlet.. and therefore there is no power to power the 3v board..

After i tried many different things... wore out my multi meter... I went back and looked at the first photo's in this thread. If you look at where the wires are soldered to the board, The signal actullay is taken form the top of the pin in the mini jack port..

[Shupe]

Yep the phone jack thing don't work.... As the tip of the pin which we think is the power outlet is actually the signal outlet.. and therefore there is no power to power the 3v board..

After i tried many different things... wore out my multi meter... I went back and looked at the first photo's in this thread. If you look at where the wires are soldered to the board, The signal actullay is taken form the top of the pin in the mini jack port..

Is the 3.54v on the circuit board better (more stable, cleaner) than the 3.3 available on the analog plug top left pin? My thought is that if this power was acceptable to power with the modification of a mini jack plug would keep from making modifications to the module itself.

[thunder550]

Hmmm...I got my MAX3232 in the mail yesterday, planning on working on it tomorrow. Will post back with my findings. Thanks for the information above guys, I'll take that into consideration when I'm working on it.

[thunder550]

OK just a quick look at the PCB says that the tip of the minijack connector is Tx, base is ground. Doesn't look like the middle contact has anything connected. Might try to connect power to the middle contact.

[vxleather]

Is the 3.54v on the circuit board better (more stable, cleaner) than the 3.3 available on the analog plug top left pin? My thought is that if this power was acceptable to power with the modification of a mini jack plug would keep from making modifications to the module itself.

There is no out put voltage to power the convertor board on the mini jack!!!

[vxleather]

OK just a quick look at the PCB says that the tip of the minijack connector is Tx, base is ground. Doesn't look like the middle contact has anything connected. Might try to connect power to the middle contact.

The middle outlet does have milli volts running to it.... I was also tempted to apply power to it and use that to power the board.. I connected the plx up naked.. (removed the red casing) and measured the voltages at where the feamle plug is soldered to the board etc etc... the middle pin connector seems to have milli volts running to it.. I think this is what confused me to start with.. I could get 3.3 volts out of the tip (presumed this would power the convertor board) then could measure milli volts out of the middle connector (presumed this to be signal ) and the base was ground...

but for some reason it does not work that way..I am not shaw where the milli volts come from and what they are for.. I am no expert in this field.. Blind leading the blind a little

[thunder550]

Yeah I'm not sure what that middle contact is used for but when I put 3.3v to it the gauge quit powering on. As soon as I removed the voltage from that contact the gauge started working fine again. Looks like my solution won't work :( I guess I'll just live with extra wires coming out of the case.

[thunder550]

Ok here's what I ended up with. Tested and working. The only real difference is that I pulled power from the posts on the back of the board instead of from the hole through the board like the OP did.

Wiring color is:

Black: +3.3v
Red: Tx
Silver w/ black heat shrink: Ground