| Electronics > Repair |
| What more i can do? |
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| Harry_22:
--- Quote from: 222Lab_Test222 on November 12, 2024, 07:39:13 am --- In working as well as non working board its same, I see a wave and a 66MHz frequency. --- End quote --- Try to stop it as I described above (you can unsolder it) and watch the beep. On working board. I have a question. What do these two LEDs do? (Please see the picture below.) Also don't forget to stop CPU clock (66MHz) and check the beep sound. PS At the bottom picture you will find some curves explanation. |
| 222Lab_Test222:
--- Quote from: Harry_22 on November 12, 2024, 08:31:48 am --- --- Quote from: 222Lab_Test222 on November 12, 2024, 07:39:13 am --- In working as well as non working board its same, I see a wave and a 66MHz frequency. --- End quote --- Try to stop it as I described above (you can unsolder it) and watch the beep. On working board. I have a question. What do these two LEDs do? (Please see the picture below.) Also don't forget to stop CPU clock (66MHz) and check the beep sound. PS At the bottom picture you will find some curves explanation. --- End quote --- Red Led is blink at startup power on, it also keep on glowing if the voltage is less than 4v, regarding other uses not sure. Green Led refers to the ok board, If it glows continuosly, not bright nor dim, then the motherboard is ok. Still, i need more details on stopping to those CLOCK signals, desolder is not possible i guess, Maybe any other options. As for the Pics, Yeah the BIOS is not getting input signals to process so BIOS not loading in non working board i guess. |
| Harry_22:
--- Quote from: 222Lab_Test222 on November 12, 2024, 03:12:15 pm --- Red Led is blink at startup power on, it also keep on glowing if the voltage is less than 4v, regarding other uses not sure. Green Led refers to the ok board, If it glows continuosly, not bright nor dim, then the motherboard is ok. Still, i need more details on stopping to those CLOCK signals, desolder is not possible i guess, Maybe any other options. As for the Pics, Yeah the BIOS is not getting input signals to process so BIOS not loading in non working board i guess. --- End quote --- It is very likely that the red LED represents a Reset state. Here the reset signal acts also as Power Good. If the green LED is neither bright nor dim, it means it is monitoring some CLK pulses. How does it glow on a non-working board? I want to stop the clock generator on the working board in order to emulate this fault. I still don't understand the reason. There is no clock frequency or the processor is faulty, for example. But in our case, several boards are equally faulty. It would be instructive if at the end it turns out that some capacitor has dried out. There is another one low loss cap right next to the processor. I found the start up sequence procedure here. It is for IBM5170 (80286 processor). https://www.minuszerodegrees.net/5170/motherboard/IBM%205170%20-%20Startup%20sequence.htm |
| 222Lab_Test222:
--- Quote from: Harry_22 on November 12, 2024, 07:47:29 pm --- If the green LED is neither bright nor dim, it means it is monitoring some CLK pulses. How does it glow on a non-working board? --- End quote --- It Sometimes glow so bright or sometimes the lED is not turn on. |
| 222Lab_Test222:
--- Quote from: Harry_22 on November 12, 2024, 07:47:29 pm --- It would be instructive if at the end it turns out that some capacitor has dried out. There is another one low loss cap right next to the processor. I found the start up sequence procedure here. It is for IBM5170 (80286 processor). --- End quote --- Could be The capacitor has dried out or maybe processor is not working as it should be. Either way the reason i hesitate to desolder is, this is only working board i have, if in case it also start showing issues then, i would not have any working boards to compare. |
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