exxos blog - random goings on

[exxos]

Just got back home, so the B1 hasn't been on all weekend.. was bit 13 failing before.. now its bit 1

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EDIT:


Fault has changed again !

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Working on bit0.. DRD0 is pulsing, but D0 output is flatlined. Some other DRDx and Dx lines are pulsing. So its like the gate is blown

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[exxos]

The plot thickens.. I get the pullup value ~4.7K on D1, but nothing on D0 !

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No connection from the MMU to IC21 pin , probably another bad via

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Bodge wire time..

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...and... success! D0 now fixed.. now I have another bad bit. You couldn't make this crap up !!

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[exxos]

D5 next.

D5 comes in at the bottom of the image (red track) then connects to the other chip above via a green track (inner layer). The green track connects to the MMU.. So there's a break somewhere around that via to the top red pad

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New bodge wire..

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...and...

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I may just unsolder all chips to see if I can see what the hell is going on..

Maybe I should just "retire" this board at this point...

[exxos]

OK so I removed the chips.. as suspected.. vias look totally missing in various places Not simple to fix without loads of bodge wires.. even so.. it wouldn't be much use for a dev board if its going to be "fragile".

I will have to see if the inner tracks are all connected.. maybe I could get lucky and just plaster solder in the hole...

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EDIT:

A quick test around, and it looks like its the "top side" part of the via which is missing from connection to top copper.. So the "good" news, is the middle copper layers seem to be connected. But with the vias being 0.2mm dia, id need some very tiny wire to reconnect the vias up.. assuming I could even get a wire though the hole in the first place, which I doubt ...

[exxos]

Bought myself a new book.. Found a "cheap" used copy, as, damn, that book is expensive.

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[mrbombermillzy]

Bought myself a new book.. Found a "cheap" used copy, as, damn, that book is expensive.

Most half decent books on any technical/engineering subjects are it seems.

I have a similar problem; finding a certain book on the latest 2 stroke engine theory is very costly.

I dont suppose you had the option of a pdf then?

[exxos]

I dont suppose you had the option of a pdf then?

I did look around the Internet but only found a couple of index pages in PDF format.. I did not really look too hard as I couldn't be bothered..

For some things I just prefer to have a physical book anyway..