| Electronics > Repair |
| ADVANTEST R9211B |
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| m k:
Floppy controller _IRQ is pin 23 and CRTC _IRQ pin 12. Try searching those also from HC148 inputs. 71054 timer chips have three possibilities, pins 10, 18 and 26. Some of those can also be connected to HC148 inputs. There are also some others, but their positions are not so straight. One is FPU, but its bidirectional pin has something in between. |
| stfjohn:
DMAC_IRQ (pin 21) is not connected to HC148. Sorry, can you be more clear about the other ICs? |
| m k:
Possible other connected _IRQ pins. 63484 CRTC 12 63265 FDC 23 82C79 KBC 4 9914 GPIB 9 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 HC148 pin 14, can you find it from LS164 input pins 1, 2, 8 or 9? Are any LS07 input or output side pins shorted to other pins of the same side? Are any LS07 output pins connected to HC148 input pins? |
| stfjohn:
The only pin I managed to check is the 9914 GPIB 9 which is connected to pin 15 of the HC148. To check all the others I have to disassemble the Main Board again and it will take me a bit of time (currently I'm busy with work unfortunately). |
| m k:
I thought you've already dismantled it. Leave top side for later. Pin 15 of HC148 is also output. Is it possible that the pin is actually 2 from the other side of the chip? That would be pretty much spot on. One other thing I've possibly forgotten. Are those CPU pins 25 and 24 shorted to ground? PAL chip left of CPU. Can you find its 1 to 11 pins connected to CPU high address pins 52 down to 44 in any way? If so then can you find same connections from PAL chip right of CPU? One possibility is that one PAL chip is not coding I/O addresses correctly and that's why there are so few _CS signals and 'not installed' on screen. Downside with that is that it has nothing to do with interrupts, unless the same PAL is also coding those interrupts. So check also if you can find those CPU pins 25 and 24 from that left PAL chip. |
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