[1000mp] Switching supply slow to start

[Mike Schatzberg]

Hello Rick:

It is pretty tough to know whether you have a bad component or a bad solder joint with a heat sensitive problem like yours.

There are a few techniques which you could try, to locate the problem area.

You may be able to heat areas of the board with a hair dryer to get the power supply playing.  This will help to localize the problem.

Then, with the supply running, use a can of cooling spray, with the spray wand, to identify the exact location of the component or solder joint.

When you know which component seems to be the problem, before you remove and replace it, reflow the connections.  Some folks just start reflowing many connections to try to locate the faulty joint, without trying to pinpoint it first.

You should be able to locate the culprit quickly and simply.

73 and Happy DXing,

Mike
W2AJI
Administrator: 1000MP Reflector
  ----- Original Message ----- 
  From: Rick Stealey 
  To: 1000mp at mailman.qth.net 
  Sent: Saturday, November 22, 2008 8:35 AM
  Subject: [1000mp] Switching supply slow to start


  The internal supply in my 1000MP doesn't like to start when the rig is cold.  As the 
  ambient temperature rises it takes off and operates normally.  I see there is no info
  in my technical manual, just a schematic which I note has FUTABA on the PCB.
  I've never tried troubleshooting a switching supply.  Any ideas as to what is most likely
  the cause?  Some resistor has changed value in 11 years?  Some capacitor is leaky?
  Transistors and ferrite transformers don't get cranky with age do they?

  Oh by the way, I am sure it's not something external to the supply (it is getting 110 v, and 
  there is no 12 volts when it is cold).

  Thanks,
  Rick  K2XT


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