Yes but as I don't know what caused this all in the first place , good
engineering practice told me that as it is almost zero cost and effort
to replace it whilst I had the PCB off the heatsink then that's what you
do!
73 Bob G3PJT
David Cutter wrote:
Nice work, Bob.
I've seen 78 series
Bob,
Other than cutting traces or removing chips, there is no easy way to
check for such a shorted condition.
I do suspect that the MAX1406 chip (U4) is the one to remove first
because it is the most likely culprit. The EL5146 chip (U6) is also on
the suspect list.
Before desoldering,
Hi Don
I was just about to send something to the reflector. Both the 1406 and
the 5146 had failed but I do not know why.
However the solution was :-
- find out which chip was crowbarring the 5v line. Pull the PIC - it was
OK in my case. Cut pin 16 on the 1406, check and resolder if OK (it was
Nice work, Bob.
I've seen 78 series regulators die with over voltage but never over current
or temperature, they have excellent protection for those.
David
G3UNA
- replace the 78L05 as its not clear how much abuse it had suffered.
73 Bob G3PJT
Bob,
Great work.
The EL5146 can be ordered from Elecraft, and if it has been discontinued
in the DIP package, the SMD equivalent will be supplied mounted on a
carrier board to adapt it for thru-hole use.
If you have the K60XV installed in your K2, the use of a non tri-state
op amp will
Hi
My CAT just stopped working and I have found that there appears to be a
low resistance on the 5v rail which supplies the PIC / 232 interface
chips. This pulls the 5V rail down to 1 v with the result that the PIC
and 232 interface chips are not operating and the 78L05 at U3 is rather
hot
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