exxos blog - random goings on

[JezC]

:yay2: :thumbup: :cheers: :2k2:

[rubber_jonnie]

She lives!!


:girldance: :girldance: :girldance:

[stephen_usher]

:dualthumbup:

[PhilC]

Long live the Frankenscreen

[exxos]

Hmmmm M'Kay....

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[exxos]

RAMdomizer soldered in:)

Next to find some DRAM to test it with :)

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[exxos]

All that was a fail... Short-circuits across the power rails somewhere :roll:

So started sucking up the VCC pins as it is the only place which can be shorted to GND... and did not find anything wrong :roll:

Loaded up the PCB file, ran DRC.. no problems found..

Tried a blank new PCB and the short is on the PCB itself somewhere :roll: :headbang:

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[derkom]

Is it just me, or do you have a track running right into those holes?

Edit: I guess it does steer around them. Looks mighty close. :)

[exxos]

Is it just me, or do you have a track running right into those holes?

Edit: I guess it does steer around them. Looks mighty close. :)

They do steer around the holes... The socket holes look like they might be Via's under the microscope, but I cannot get continuity across any of them...

The board alignment top and bottom looks pretty spot on.. :shrug:

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I might just hook it up to my big power supply and crank up the amps until something catches fire :twisted: :twisted:

[exxos]

Right, here is a exxos lesson in fault finding a power rail short..


First up a proper low resistance meter..

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Basically what we do is check the resistance across various capacitors around the board and look at the resistances...


I started at the bottom right corner of the board working my way up with and to the left taking note of the resistance...Which is 84.2mR..

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Moving upwards on the board you can notice the resistance gets slower, so we are getting closer to the short! Now 35.9mR!

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Now I can only move to the left...So moving along one by one the resistance got lower and lower until there was nowhere else to go...

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This is the lowest resistance point on the whole board on the power rail at 11.3mR.

So checking what capacitor that is on the PCB files...

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D'oh! :headbang:

It looks like when I moved the capacitors about, to the right, I must have missed that one for some reason it should have been further to the right :roll:

Bodge wire time...