mkarcher wrote on 2022-08-31, 18:52:
You need to find out where the power is interrupted. You need to understand that your mainboard consists of four layers of trace […]
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biessea wrote on 2022-08-31, 17:29:
Thanks a lot, I am thinking about that, the keyboard has no power. And problably mess around the motherboard.
How can I fix if it has no power?
You need to find out where the power is interrupted. You need to understand that your mainboard consists of four layers of traces. You can easily see the traces on the top and on the bottom of the board. The two inner layers actually are power planes. They are solid areas of copper with small holes in them. One of the inner layers is connected to ground and the other one is connected to +5V. As you get beeping, +5V and ground are definitely getting around on the board, so the power planes themselves seem to be powered.
For the keyboard supply, the outer edge of the wire labelled "F1" is connected to the +5V plane. On the back of the board, a trace from other end of F1 runs to one end of L1, and the other end of L1 is connected to one pin of the keyboard connector. Also, the end of L3 that is farther away from the keyboard connector is connected to the ground plane. The end of L3 that is closer to the keyboard connector is connected to a pin of the keyboard connector via a trace on the top of the board. That trace might be broken right next to the keyboard connector. You need to check continuity between +5V on the power plane (e.g. a +5V connector of the AT power supply) and the pin and the keyboard jack that should carry +5V. You also need to check continuity between GND (e.g. one of the center pins of the AT power supply connector) and the keyboard jack pin that is connected to L3. If you don't have a tool to check continuity, go buy any multimeter. While there are a lot of deficiencies on budget ($5-$10) multimeters, they generally work for continuity tests and probing around in low voltage circuits like computers.
If you find the place where the power delivery is interrupted, you need to fix the trace or solder a wire to the board as replacement for the broken trace.
Hey, thank you SO much for all these hints.
I admit I have to read them a lot of times ot understand well, I love computer world and I love to make a lot of things with them, like video card bioses, like overclocking, but I admit this is a board too old for me.
Anyway listening PC speaker sing ignite on me a little smile.
I have a nice multimeter yes, a good FLUKE 15B. And yes, I can try to check continuity between traces.
But please, expalain me better, I cannot really understand L3, L1, F1, I don't really know what you are speaking about my dear.
I think that together we can go on and finally solve that problem, so I can have a nice rare motherboard and a lot of people can be jealous 😉
Please, explain me better, tell me what I have to do.
Thanks a lot, another time.
PS: I am buying a VGA ISA card.
Computer lover since 1992.
Love retro-computing, retro-gaming, high-end systems and all about computer-tech.
Love beer, too.