micro 7" dead?

Hello,

Suddenly my 7" micro board seems dead, well not suddenly.
I painted the full board with hummie-seal (an electronics sealant used by
the navy that isolates and protects), after drying I started the board and
all seems fine and it was working perfectly.
Now a week later the board don't boot anymore, leds go on and the screen
lights but no boot and nothing in the serial console (minicom) nomather
NAND or NOR position.
Is there a way to debug the boot process to see where it stalls or does
anyone have some other suggestions or tips for me besides "don't use that
sealant anymore"?

JTAG?

best regards
Tom

before some shout at me.... it could happen, it happened before...
the lacquer you used are expanded slightly, and could lift up some of the
pin from the pcb..
try to heat up the board !

Is hummie-seal recommended for "tropicalising" PCBs?

I be careful about trying to heat up the board, ie to reflow temperatures
you might cause more problems.  I would be surprised that anything you
sprayed on a board would lift normally good connections.  The reflow
process seems to be well under control on these boards.

Dumb question: Is the NAND/NOR switch still switching? Make sure by
measuring...

Maybe sealer got into switch?

In NAND position the center pin and the one on the NAND side are connected.
In NOR position all 3 pins are connected, is this correct?

Well, the switch is not on all four schematics that I have for the mini or
micro! Also, don't see where CON5 is on the board.  Looks like CON5 has
been replaced with the switch.

Looking at sheet 2 of the mini2440 schematic it looks like pin OM0, either
gets pulled up to VDD33V (3.3V) for NOR boot OR pulled down to ground for
NAND boot.  Suggests a normal SPDT switch to me.

Your switch appears faulty.  I would check that OM0 does NOT get pulled up
to 3.3V, in the NOR position, with a voltmeter before ripping it out!

In NAND position middle and nand side are 3.3V in NOR position all 3 pins
are 3.3V

But I sealed the board in working state, so if switches are sealed solid
they are still in working state. It would explain why I can't boot the
board in NOR mode but it should by default boot NAND.
I think I will have to order a new one I am afraid...

Some chips fried because they couldn't dissipate the heat anymore...

OK, missed that it didn't work in the NAND position.  Haven't you got the
RS232 connected up and running minicom on the host to see what is happening
during the boot process?

Yes I have it hoocked up and minicom running, nothing to see nomather NAND
or NOR boot.