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

[Morris Wideman]

That is a interesting situation you have Glenn. I would carefully inspect any solder joints as mentioned by WB4U there have been lots of instances of those noted in this list. 
There are tools to remove the molex type pins and you could use something like a brass tube to fashion one out of it just needs to thin to slide over the metal parts. I have tightened up the female side by using a small thin screwdriver to go around the outside and force the metal part to close up.
It will be interesting to hear what you find. Best luck.
Morris WA4MIT


--- On Mon, 2/16/09, Glenn Rattmann <k6na at cts.com> wrote:

> From: Glenn Rattmann <k6na at cts.com>
> Subject: [1000mp] Mark V turn-on, power-up issue
> To: 1000mp at mailman.qth.net
> Date: Monday, February 16, 2009, 3:21 PM
> 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
> 
> 
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