My brother brought me a device known as a Tech-2 scanner, which is
used by GM dealers to troubleshoot and diagnose problems with GM cars
(my brother is the shop manager). He said the tech that was using the
scanner heard a POP, and then the device went dead. To get it
repaired via normal channels would cost over $800, so he wanted me to
take a shot at it first. I took it apart and the trouble appears to
be in a DC to DC converter that is mounted on the main circuit board.
It is made by BTCPower, and the part number is 4BE-01T-02. The IN
voltage is 7-18vdc, and the out is 5vdc at 2000ma. I went to the
BTCPower website and found the specs on the device, but apparently
these things can sometimes be manufactured custom. In the case of
THIS converter, the IN consists of THREE pins, a +, - and one labled
"R". The PDF on the web site does not have this extra "R" pin, so I'm
assuming it's a CUSTOM version the 4BE-01T device referenced on their
web site, specifically designed for use in the Tech-2.

I found and ordered a replacement from JAMECO electronics (#216961),
but it, like most other replacements I looked at, does not have this
"R" pin. I applied power (exactly 12v) to the old converter and
measured the voltage between ground and pin "R", and I read 4.77v. If
I raise the input voltage, the voltage across ground and "R" goes up a
little. If I lower the voltage the voltage across ground and "R" goes
down a little. So I'm thinking it some sort of "reference" voltage
used by the scanner for some reason.

Unfortunately when I examined the circuit board the "R" pin *is*
connected, to a small resistor. So it does SOMETHING, I can't just
leave it unconnected. That means I need to figure out what the "R"
pin is on the old converter, or the new one I install probably won't
work right.

By the way, forget about tracing the "R" circuit. The Tech-2's main
circuit board is jammed with high density, probably proprietary, ICs
on BOTH sides of the board, not to mention it's a high quality,
multilayer circuit board. I can diagnose the bad converter, test some
surface mounted devices such as diodes and capacitors, but that's
about it.

Any suggestions?

Thanks,

Bill