[1000mp] Mark V turn-on, power-up issue

[Glenn Rattmann]

List,

I've had an intermittent turn-on issue with one of my Mark V 200-Watt 
radios, where it won't light up at all.  I have two rigs and two 
FP-29 (and two cables), so I have definitely isolated the problem to 
the one radio.  The radio also more than once has just gone black 
unexpectedly while in use, and won't restart when this happens.  If 
it sits cold for a week or two, it might come back up normally, only 
to fail again later.  Lots of wiggling around with the DC cable/FP-29 
hasn't fixed it.  I searched the 1000mp archives for FP-29 or other 
power-up issues and didn't see anything exactly like this.

I've got this radio spread all over the bench now.  The DC cable 
comes to the rear apron and meets a Molex-type bulkhead mount 6-pin 
connector there.  I've removed the connector from the rear 
apron.  The six conductors in the harness go almost to the front of 
the radio, under the fan, where four of them curve back to the power 
input board accessible by removing the fan and the heatsink/amplifier 
module.  The other two conductors (light gauge) terminate in a little 
connector mounted to a bracket near the power-on switch, but 
interestingly there is no mate to that connector-- it's just floating there.

The four other wires terminate on the DC power board in lugs bolted 
to the board.  The board has a few capacitors and a couple of relays, 
and the heavy output wires then lead from the board into the RF power 
amp module.

I'm thinking of replacing the relays on the board as a shot in the 
dark.  Or, the intermittent may be caused by either poorly crimped 
lugs on the high current leads (at least one looks insufficiently 
crimped, but it's a guess), OR poorly mated pins inside the 
Molex-type connector (I assume it is not a true USA Molex-- it's not marked).

Before putting the radio back together, I will improve the crimping 
on all the DC lugs, and add solder to them so I can rule out this as 
a possible problem source.

Second, I want to pull the pins out of the DC connector, examine the 
pin-crimping, and perhaps solder them, too.  I know Molex has a 
series of pin-removal/install tools for their various connectors, but 
has anyone identified the correct tool for this particular Molex-like 
connector?  FYI the pins are not round, they are hollow square, or 
perhaps rectangular, in section.  I want to obtain the tool if 
possible (have not started a search with vendors yet, because the 
connector mfr. is unknown).

I will also go into the amp module to inspect how the DC voltage 
leads terminate in there, and inspect everything.

When this radio lights up, it works perfectly in all respects, 
usually for hours at a time, so I don't really suspect the amp-output 
devices-- but I am open-minded.

By the way, I know of two people who after difficult troubleshooting 
did eventually learn that they suffered from improperly crimped pins 
in the Molex connectors of the power supply leads in their kw RF 
amplifiers (the connector between the removable power transformer and 
the amp wiring harness).  This led to intermittent filament 
voltage.  So, these types of connectors are not always perfect, and 
if intermittent, can be a bear to discover and fix!

Any ideas on this issue are appreciated... thanks!

--Glenn K6NA