lm7805 problem revisited
@ JS
This line in your tutorial on page 76 post 2275 is what I am trying to solve with the board. I have found the problem with the jumper and solved it on one board only. The second board has this problem, see below, when the jumper is installed.
"3.
Connect GND of your meter to GND on connector X8 and let it sit there for rest of test procedure. You will move the active probe only.
Measure input voltage at connector X8 and check if it is still around the value you measured before in idle mode.
If you read some few volts or less you have a short circuit. Switch off instantly and check."
The voltage at the input is drawn down on the entire board from about 18 volts to 3.88 volts. Not just at the lm7805. But along all of the 12 volt circuit from the input to the diode the lm7812 and the 7805. No matter where I test it is the same when the jumper between the 7812 and the MIC4452YN is installed in the circuit on this board only. After removal the voltage readings return to a normal reading. In test number 3 I would consider this to be low voltage in these readings. This would indicate a short but since it only occurs when the jumper is installed it leads me to believe that the short is in the 7805, am I correct in assuming this? Or is there another explanation?
These regulators only cost about 60 cents each, I will order some more. It hardly seems worth the fuss.
Cheers
Garry
@ JS
This line in your tutorial on page 76 post 2275 is what I am trying to solve with the board. I have found the problem with the jumper and solved it on one board only. The second board has this problem, see below, when the jumper is installed.
"3.
Connect GND of your meter to GND on connector X8 and let it sit there for rest of test procedure. You will move the active probe only.
Measure input voltage at connector X8 and check if it is still around the value you measured before in idle mode.
If you read some few volts or less you have a short circuit. Switch off instantly and check."
The voltage at the input is drawn down on the entire board from about 18 volts to 3.88 volts. Not just at the lm7805. But along all of the 12 volt circuit from the input to the diode the lm7812 and the 7805. No matter where I test it is the same when the jumper between the 7812 and the MIC4452YN is installed in the circuit on this board only. After removal the voltage readings return to a normal reading. In test number 3 I would consider this to be low voltage in these readings. This would indicate a short but since it only occurs when the jumper is installed it leads me to believe that the short is in the 7805, am I correct in assuming this? Or is there another explanation?
These regulators only cost about 60 cents each, I will order some more. It hardly seems worth the fuss.
Cheers
Garry
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