Thanks Dave. P type? Or N type? MOS? JFET? ? ? ?

 

Bingo! It's a Tl431 zener, the two resistors 4701( 4.7k) 1201 (1.2k) set the voltage, you can make the 1.2k smaller or increase the 4.7k to get the ratios, i would go with the 1.2k and drop it to 1.06k by putting a 9601 (9.6k) in parallel , this will give you 13.6V output...

Vout now = (1+ 4k7 /1k2) x 2.5v= 12.3V.
Vout new = (1+ 4k7 /1k06) x 2.5v = 13.6V

The close tolerance resistors with 4 digit codes are a dead giveaway - if they're near a '431; you can be sure they're the voltage setting divider.

 

WOW! GOT GREAT SENSITIVITY with a 5K pot and a 4.7KΩ. Added a switch in so I could parallel this setup and control the voltage OR I can switch it off and drop back to 12.2 volts.

Project done!

 

Looks like most of the FTA infor is here: http://www.inpowersemi.com/en/productshow.aspx?cateid=67&productsid=2715

It looks like you have to register to get outlines and real datasheets. It's Chinese. You can make the registration page english understandable with Google translate.

 

Long wires in the feedback circuitry is a no no.

 

Long wires in the feedback circuitry is a no no.

20 gauge wires going to my mod are less than an inch, but close to it. There was no other way around mounting the pot and switch.

 

Thanks Dave. P type? Or N type? MOS? JFET? ? ? ?

N type Mosfet.