Lawrenciumbc
- Nov 2, 2015
- 41
- Joined
- Nov 2, 2015
- Messages
- 41
I am a building project (DSO138 oscilloscope) I bought just to help me practice soldering, circuit building etc... to assist my electronics study, but during troubleshooting after the build, there appears to be a mystery voltage drop accross a diode I cannot explain.
The diode in question (attached picture - diode labelled D2) is pretty much the first component after the 9V power supply and is a 1N4004 diode. The schematic says that the voltage pre-diode should be around 9.39V (I am measuring -9.33V for some reason but at least a voltage is there?), but only around 200mV after the diode.
I've tested the forward voltage drop of the diode on the board and it is measuring around 0.5V which I believe to be correct as the next test point after the diode on the schematic is meant to be 8.6V which would approximately work out correct.
As an inexperienced electronics hobbyist, I don't understand how the diode performance can measure 'correctly' (or at least as expected according to the schematic) when measured on its own, yet appears to drop significantly more voltage in reality?
Is this a common scenario that can happen? what should be my next port of call for checking be? I am thinking of replacing the diode but as I say, the diode appears to be fine (according to the diode measurement mode on the multimeter) and so wondered if I should look at something else first.
The diode in question (attached picture - diode labelled D2) is pretty much the first component after the 9V power supply and is a 1N4004 diode. The schematic says that the voltage pre-diode should be around 9.39V (I am measuring -9.33V for some reason but at least a voltage is there?), but only around 200mV after the diode.
I've tested the forward voltage drop of the diode on the board and it is measuring around 0.5V which I believe to be correct as the next test point after the diode on the schematic is meant to be 8.6V which would approximately work out correct.
As an inexperienced electronics hobbyist, I don't understand how the diode performance can measure 'correctly' (or at least as expected according to the schematic) when measured on its own, yet appears to drop significantly more voltage in reality?
Is this a common scenario that can happen? what should be my next port of call for checking be? I am thinking of replacing the diode but as I say, the diode appears to be fine (according to the diode measurement mode on the multimeter) and so wondered if I should look at something else first.