I'm trying to locate the overall system controller on a video board, that
handles IR remote, physical keypad functions and power on/off of main power
supply etc. Mulilayer board of course but all I can find is dedicated
digital video processing chippery. This is quite a thick pcb , does anyone
hide SMD controllers recessed within the thickness of a pcb? there is a
mysterious black piece of plastic in one area , well bonded to the pcb but
no outline of anything underlying it

I warmed up and lifted that patch and nothing hiding underneath. I've
managed to identify, surprisingly, all chippery , all 29 SMD devices with 8
or more pins and all are dedicated video /audio/MUX/memory /op-amp packs
etc, with pinouts etc avaialble for all , but no uC or PIC found for system
control

N_Cook wrote:
I'm trying to locate the overall system controller on a video board, that handles IR remote, physical keypad functions and power on/off of main power supply etc. Mulilayer board of course but all I can find is dedicated digital video processing chippery. This is quite a thick pcb , does anyone hide SMD controllers recessed within the thickness of a pcb? there is a mysterious black piece of plastic in one area , well bonded to the pcb but no outline of anything underlying it


It could be integrated in the video processor, it is in most digital decoders for TV.

Jeroni Paul wrote in message
...
N_Cook wrote:
I'm trying to locate the overall system controller on a video board, that
handles IR remote, physical keypad functions and power on/off of main power
supply etc. Mulilayer board of course but all I can find is dedicated
digital video processing chippery. This is quite a thick pcb , does anyone
hide SMD controllers recessed within the thickness of a pcb? there is a
mysterious black piece of plastic in one area , well bonded to the pcb but
no outline of anything underlying it


It could be integrated in the video processor, it is in most digital
decoders for TV.

+++++
And so it was. Although no schema for this unit , googling on the 2 main
"video " processor chips and filetypedf threw up a few detailed
schematics, to then targetted probe under the big BGA, to check traces.
Is there a special probe for doing this, thin , tough, insulated , with
graduations for indicating which row/column depth from the edge ?

N_Cook wrote:
Is there a special probe for doing this, thin , tough, insulated , with graduations for indicating which row/column depth from the edge ?


I do not know, but it comes to mind you could use enamelled wire with the insulation removed on a small area at one end. Drawing a small scale on the wire may be the hardest part but if you are interested in just a few pins that reduces the number of marks to place.

Jeroni Paul wrote in message
...
N_Cook wrote:
Is there a special probe for doing this, thin , tough, insulated , with
graduations for indicating which row/column depth from the edge ?


I do not know, but it comes to mind you could use enamelled wire with the
insulation removed on a small area at one end. Drawing a small scale on the
wire may be the hardest part but if you are interested in just a few pins
that reduces the number of marks to place.


+++++
I have some .08mm tungsten wire that is just about stiff enough as a probe ,
for this Ti ADP2000 BGA could have been larger diameter, laquered over and
just the end ground down clean. A refinement I suppose would be contrasted
markings along the laquer for row/column spacings, I think up to 5 deep in
some areas of these

DDP2000, should have been , too much sun today