| Electronics > Repair |
| BK Precision 2120 trace issues |
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| vexatag:
--- Quote from: bdunham7 on August 05, 2020, 03:57:35 pm ---OK, why don't you see if you can get your soundcard scope to work with your signal generator and show some waveforms. --- End quote --- Done, waveform screenshot is attached. --- Quote from: bdunham7 on August 05, 2020, 03:57:35 pm ---Then you can try feeding them in to see if you can trip the comparator. --- End quote --- What do you mean by that? Use the signal generator as the EXT input and run the previously mentioned tests? |
| bdunham7:
Yes, do the same tests to prove out the system. Make sure you have the ground side of the signal generator and the soundcard scope both together at the same point (probably the black lead of your BNC clip cables). You may want to pretest each new test point with your DMM in AC mode to make sure there isn't more than a few volts present before hooking up the computer. Then, one additional step. If you have a signal at S603, connect the scopecard to the #9 pin of U601 (you may want to either look up IC pinout rules--or post a photo) and see if you can get any signal by adjusting the trigger or even pushing it in and using auto. You can see on the schematic that if finding and connecting to pin 9 is too hard, then the correct sides of R470 or R632 will do. |
| vexatag:
So, BNC 1: red lead to signal gen out, black lead to signal gen gnd, connector to EXT. BNC 2: red lead to test point, black lead to signal gen gnd, connector to soundcard scope. Is this a correct understanding? |
| bdunham7:
Yes, that's it. |
| vexatag:
The ends of my bnc probes are bent out of shape and refuse to stay clipped to the gnd/out pins of the signal generator or the test points of the switch. |
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