Garmin GPS overheating problem

[Les Unwin]

Hi, I have a Garmin 4008 GPSMAP unit. It's a beautiful bit of gear, and with depthsounder module and transducers, cost about $3000.
Problem. when I turn it on it will run for as long as I want, If I turn it off, It will not restart and Takes about 20 minutes to cool down to where it will turn on.
Normally draws 1.4A, 12V and the boards run at 7. 2V and 5.08V very stable. The 5.08V runs a second cooling fan , the map system and switches (on/off, and all settings).
When the problem occurs and I switch on the 5.08 volts becomes 2.2v and power in drops to 0.27A (a fan on the power board turns on).
I believe I've tracked it down to a capacitor (ceramic, 16V,470, 105 degrees C). When I spray freezer on that cap, the voltage comes up to normal and the rig starts. I changed the cap and now it is not so bad,but will not switch on for a couple of minutes. If I leave the case open, this stops the problem.
Any ideas, should I use a different cap?
Garmin Australia won't look at it and says I should bin it and buy another (Garmin!)
Won't give circuit diagrams.
I told them that is like taking my 2012 favourite car and pelting it when the problem is a spark plug???????

Any advice?
Les

 

[Bluejets]

Sounds like some form of regulator gone bung or bad solder joints somewhere.

 

[73's de Edd]

Sir Les Unwin . . . . . ..
. . .
One fine looking unit !

I believe I've tracked it down to a capacitor (ceramic, 16V,470, 105 degrees C).

That high of a capacitance, of 470 ufd and specific temp rating would be indicative of an electrolytic type of cap, and not a ceramic.

Do you have enough tech and component savvy to be able to search out the power regulating components and give us some good well lit photos of that circuitry . . .possibly that mentioned cap is also being within those boundaries.

It would also be helpful to run the unit for about an hour warm up time, and then place a fingertip atop each of any associated electrolytic cans, to see if any exhibit a slightly . . .or greater temperature.
Even MO' better . . . . . is in case you happen to have . . . or can get the use of a laser spot temperature gun for that analytical duty..

73's de Edd

 

[kellys_eye]

Grrr... one thing that grinds my gears is manufacturers that use the 'buy another (one of our) unit replacements', especially if they use the 'sorry, no schematics/spares' line (liars!) and I've even repaired marine equipment free of charge just to give the manufacturers the finger for that kind of attitude!

I now look after and repair my F-in-laws boat and all the electronics on it as he's of the same opinion and happy for me to do so. If I'm in the boat yard and people ask (nicely) I'll even fix theirs 'just for the heck of it'. The older the equipment, the more likely I am to want to fix it for free!

And with the tightening economic situation - not to mention the sheer wastefulness of dumping equipment simply for increased sales - I do what I can to frustrate the system!

Hope you get it fixed @Les Unwin