Electronics > Repair
ADVANTEST R9211B
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stfjohn:
The only connections I can locate are: 
HC148 pin 11 connected to R35 pin 2;
HC148 pin 12 connected to R35 pin 4;
 HC148 pin 13 connected to R35 pin 3;
 I can't locate anything else unfortunately...
m k:
I misread reply #168, so the actual pin is 13 and not 1, 2 and 3.

Below are two cases, Totem Pole and Open Collector/Open Drain.
Can you find any connections?

Timers can use both levels, 82C79 KBC 4 is always active high.
So KBC is different and timers can be so also, but not necessarily.

If LS164 outputs are not clearly serial to parallel outputs one output can be KBC IRQ, it goes so that LS164 is delaying the actual IRQ request.
Leftmost timer can be there also, but its internals can do delaying much easier.
The whole thing is a bit far fetched, but can you find from where LS164 pins 1 and 2 are coming?

Keep in mind that your probes are also not necessarily connecting every time.
Some legs can have something transparent covering and insulating them, pads also.
So check that you can short probes over a component pin or other measuring point you're going to use.

Some components are still unknown.
A chip beside PAL chip and under 32081 FPU on 3rd picture of reply #158.
4th picture of reply #158 has few fuzzy ones, a chip between RTC and F169, and chips above and right of leftmost F240.
If you like taking new pictures instead of naming them, use different camera angle.
All camera angles are bad for some directions and very good for some others.

Take also couple pictures from the other/under side of the PCB.
One location is those four chips left of CPU.
Use two different camera angles, maybe a bit from left and right.
Main goal is to record how HC148 and LS07 are connected, others are secondary.
Other location is area below FPU and printer connector, areas below near by HC138, timer and PAL chip should also be visible.
Use two different camera angles again.

TP source
63265 FDC 23
71054 U52 10
71054 U67 10
71054 U86 10
71054 U52 18
71054 U67 18
71054 U86 18
71054 U52 26
71054 U67 26
71054 U86 26

TP destination
LS07 pin 11
HC148 pin 1
HC148 pin 3

OC/OD source
63450 DMAC 21
63484 CRTC 12

OC/OD destination
HC148 pin 12
HC148 pin 13
stfjohn:
LS164 pin 1 is connected to C34 which, on the other side, is connected to HC138 pin 8.
LS164 pin 2 is connected to R34 pin 1.
m k:
So the capacitor is delaying pin 1 going up.
That can be a time delay for reset or any general hysteresis control of what ever.
stfjohn:
Photos.
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