[Collins] HF-380 display problem

[jeffa@ix.netcom.com]

Take a look at the 5 volt power to the front panel's display circuitry with a 'scope.   Although I didn't have exactly the same problem, I did have a display issue that was traced to the 5 volt power regulator (mounted near or on the front panel assembly, but I no longer recall exactly where) oscillating under certain load conditions (relating to how many segments were switched ON).  Fixed it by adding more bypass capacitance right at the regulator's input, PER THE DATASHEET (which it seems the Collins' engineers ignored).

Your problem may have a similar root cause.  It's worth a look.

Good luck!

- Jeff, WA6AHL

-----Original Message-----
From: Ian McLean <i_mclean@yahoo.com>
Sent: Nov 13, 2003 4:19 PM
To: Collins List <collins@mailman.qth.net>
Subject: [Collins] HF-380 display problem

With the 651S-1 problem solved, I now have a HF-380
that exhibits a problem that affects the display and
possibly the filter switching.
At initial swith on the display shows the usual
15.0000 but the if the frequency is changed the 10's
digit tries to display a 5 (top left segment not lit)
and the remaining display segments do not seem to
multiplex properly.
I have replaced the driver chips without success.
Has anyone had any expeience of this problem or one
similar to it before??

73, Ian, VK3JQ


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