| Electronics > Repair |
| ADVANTEST R9211B |
| << < (35/39) > >> |
| 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. |
| Navigation |
| Message Index |
| Next page |
| Previous page |