Fw: sb104 repair tip

[Kees & Sandy Talen]

There are several other "close contact" parts in a SB-104(A)
....to the metal partitions and also the metal card guides on
the side. Always a good idea to look down on the installed
cards with a good flashlight and see what's too close (and
may give you problems later).

Another point to check is the wiring around the two pass
transistors in the power supply. Easy to get a short.

Been there too.

73s  Kees K5BCQ


----- Original Message -----
From: mike bryce <prosolar at SSSNET.COM>
To: <HEATH at LISTSERV.TEMPE.GOV>
Sent: Monday, April 30, 2001 7:31 PM
Subject: sb104 repair tip


> 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"
>
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