Electronics > Repair
ADVANTEST R9211B
<< < (37/39) > >>
m k:
First picture, bottom side trace closest to PCB edge, from HC148 pin 13 pad towards CPU.
I can't see it connecting.

Another case, 2 + 3 pads near CPU, where topmost connects to HC148 pin 13.
Lowest of the right triplet, bottom side trace connects to HC148 pin 7, I can't see it connecting to anywhere.
Maybe there is too much light.

First picture and R35 pin 3.
Left of pad above it is trace from above somewhere that turns to the pin, that trace is probably from the topmost of 2 + 3 pads.
Bottom side picture has white line blocking the view, but seems that nothing is connecting there from under the white line.
Top side picture has clear connection to lower right corner of the pad, but so seems to be to upper left corner.
Is the upper left corner connection real?

HC148 pin 13 must still connect to somewhere else, but everything seems to be a dead end.
stfjohn:
The problem with the motherboard is that it is multilayer (not just double-sided!) and therefore it becomes extremely difficult to locate the connections!
m k:
You can make assumptions, like hidden part of straight line.
It's also a fact that none of those pads are without a reason.
But generally and without any luck it is very difficult.

Are there 4k7 ohms between R35 pins 1 and 3?

You can concentrate to HC148 pin 13, sooner or later its source must be found.
Bottom side has nothing, but check its connections to all pads around.

One other possibility is to try other signals that are sort of related.
LS07 pins 2, 4 and 6 are shorted and go to CPU.
Check where they go, CPU pins 10 to 13 are good candidates.
stfjohn:
I checked practically everything: yes, there are 4.7 Kohm between pin 1 and pin 3 of R35.
 Pin 13 of Hc148 is connected only to pin 3 of R35 and nothing else!
 Pins 2-4-6 of LS07 are connected to pin 10 of the CPU.
m k:
Ok, then we accept that source for HC148 pin 13 is R35 pin 3 and interrupt priority level 3 is not used.
But interrupt priority level 3 is active, all the time.

Do the same search to HC148 pin 12.
If you can't find it going anywhere  else but R35 pin 4, change HC148, assemble the machine and see what it does.
Maybe you should change HC148 anyway.
Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod