This question with such a heading came to us from the reader Alexander.
I remind you that this is the 35th publication in the Q&A series. You can familiarize yourself with some of the past parts by clicking on the links after this publication.
The text of the question itself was as follows:
Hello! I have a problem. I am a beginner radio amateur, a little oak, I cannot check the control points correctly and what readings there should be on the multimeter itself. We have a bbk ms970s home theater amplifier board, the system lay for a long time and did not start. I dropped 2 burnt resistors, changed it to effect 0.
I considered the issue and advised Svetlana within the framework of my knowledge and qualifications as follows:
Good day!
If you are a beginner radio hobbyist, then a home theater amplifier board is not the best example for training. To check the control points of a device, you need to know its scheme and navigate, at least in approximate readings. Specifically, I did not find your bbk ms970s home theater amplifier circuit, so I will give an example of a similar device:
If your circuit has an identical design, then checkpoints are checked against the general output and the controlled object. The multimeter is switched to the voltmeter mode, and all measurements are made when the operating voltage is applied to the amplifier. The check is carried out to determine whether the voltage at the test point corresponds to the factory data. This method was often used in old Soviet televisions, since they included a circuit and a table with voltage values in the package with the passport.
To understand such an amplifier, you will also need both a circuit and a table of factory voltage readings at the test points. Measurements are made in the order of power supply - from the unit to the output from the amplifier board. If there is no voltage at any point or does not correspond to the factory data, then the amplifier unit is faulty.
P.S. Link to some past parts - Part 34, Part 33, Part 32,Part 31, Part 30, Part 29.