[Heathkit] A capacitor tip for other "Mohican" rebuilders

[Philip Atchley]

Hi,

I just thought of a tip that others who may work on the Mohican may wish 
to know about (or maybe it's already common knowledge).

The set uses a POSITIVE ground 12 Volt supply, batteries.  On the main 
PCB board is a plastic electrolytic filter capacitor "can" that contains 
3 100 uF capacitors.  Instead of the "usual" Common Negative lead of the 
capacitor, this one has a common POSITIVE lead, which I'm sure nobody 
makes anymore.

I found that after removal of the plastic 3 unit capacitor it wasn't too 
difficult to mount 3 separate capacitors in the same space on the board. 
What I did was stick the NEGATIVE lead of the capacitor straight down 
through the PCB hole and bend the positive lead flush to the board and 
insert through the ground hole near the edge of the PCB board.  If 
you're careful you can get the positive leads of all three capacitors 
through that one hole.  I then used hot glue to bind the three 
capacitors into one unit and to the board for strength.  It's still not 
too difficult to remove if you need to, and if done carefully, looks 
quite nice too.

Tips.

1.  Like many early Heathkit PCB's this particular PC board is very 
prone to heat damage lifting the pads.  It is FAR easier to work on the 
set if you carefully remove all the wires from the board and work on it 
out of the set. Especially if there is much work to be done (like there 
was on this one).

2.  I removed "most" of the feedthrough posts (test points etc) from the 
PCB.  I found where many were loose, and at least two had torn their 
respective pads. The ones in this set at least didn't take solder well 
and that may have been part of the problem.

3.  In replacing the capacitor "can" mentioned above I used a 470uF 
capacitor in the first stage and 100uF units for the other two, all 
rated 25 Volts.  This way if I decide to use a wall wart to power the 
set sometime in the future there is some extra filtering.

73 de Phil,  KO6BB
991 Different NDB's heard to date.

http://www.geocities.com/ko6bb/
Merced, Central California, 37.3N  120.48W  CM97sh 



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