"Eeyore" wrote in
message ...


robb wrote:

Regarding the L387, since i had already removed it hat was
asy
to test.

I am pretty sure it is bad from what you explained. that is
5V
regulators only output 5V .

when i applied a 5V/1A DC source to Vin/GND i measured 3.47V
between Vout/GND.
when i applied a 18 V / 3.5A DC source to the Vin/GND i
measured
8.37V between Vout/GND

With a load or no load ? If there was no load on the regulator
output then
that's quite possible even for a good L387. You must have a
load resistor of
around 470 ohms on the 5V output for testing for the chip to
regulate properly.


ok, i set it up as you suggest a 470 Ohms between Vout and GND
(Pin3) with 16v/3A DC source connected to Vin and GRD. The
measurement between Vout and GND was 8.03 V when i put a LED in
series with 470Ohms i get 7.92 V measured accross Vout and GND.


It may not be necessary. Your testing used flawed methods.


that is why i am seeking help from "the group", "the fountain"
of electronic knowledge

thanks for help graham,
robb