sb104 repair tip

[mike bryce]

Boys and girls....

once again I find myself buried up to my elbows inside a sb104.

here's tip that I have to pass on. took me hours to find out.


here's the problem

The TX IF board was kaput. Fixed the problem. It worked just fine in the
extension board. However removing the extension board and plugging the TX IF
board into its socket, the radio quit. The premix signal would be gone, the
radio's T/R relay would click and it would just set there. Lift the TX IF
board out if its socket and whoa! The radio sprang to life.  Back to the
extension board and the thing worked fine again.

Plug the TX IF board back into the radio, and whoa! Dead radio...

Now I was just about ready to fly in the pope (he was busy working on a
windows NT problem) when I found the problem.

On the TX IF board there are two chokes that feed the +11 volts to the
predrivers. They are L323 and L324. They are rather strange looking guys,
not so much looking like chokes but rather like larger disk capacitors.

There are two pins that connect to the pc board. These pins extend above the
part ever so slightly.

and when you push the board down into the socket, those pins touched the
case. OHMYGOSH! That shorted out the +11 volts and that's what killed the
radio.

The Fix? Push the damn things out of the way and as a extra measure, wrapped
a layer of tape around them.


--
Mike Bryce WB8VGE
SunLight Energy Systems
"Electricity at the speed of light"

Listserver Subscription:listserv at listserv.tempe.gov - "subscribe heath 'name' 'call'"
Listserver Submissions: heath at listserv.tempe.gov
Listserver Unsubscribe: listserv at listserv.tempe.gov - -"signoff heath"