Have I measured the DC between the amplifier ground and the RCA pin? it turned out 0.02 V. Did I measure it correctly?
What is the DC voltage on all 3 terminals of Q319?
Post using the primary ground AND using the negative speaker terminals as reference (two sets of voltages).
What is the resistance between the negative speaker terminals and the primary ground, no RCAs plugged in?
Post using the primary ground AND using the negative speaker terminals as reference (two sets of voltages).
What is the resistance between the negative speaker terminals and the primary ground, no RCAs plugged in?
The power supply voltage is 11.88 volts.
DC voltage at terminals Q319:
between common ground and Q3190:
1. 7.72
2. drops to 0V
3. 8.2
between left speaker:
1. drops to 0V
2. 4,51V
3.Drops to 0V
The resistance between the negative terminals of the speaker and the primary mass is infinity.
DC voltage at terminals Q319:
between common ground and Q3190:
1. 7.72
2. drops to 0V
3. 8.2
between left speaker:
1. drops to 0V
2. 4,51V
3.Drops to 0V
The resistance between the negative terminals of the speaker and the primary mass is infinity.
Connect a jumper between a negative speaker terminal and the primary ground and re-do but you only need to give the measurement from the primary ground.
The supply voltage is 14.4 volts.
DC voltage at terminals Q319 between common ground and Q319:
1. 9.74 V
2. ≈ 0 V
3. 10.23 V
After installing the jumper between the negative terminals of the speaker and the primary ground, the DC voltage at terminals Q319 between the negative terminal of the speakers and Q319:
1. 9.74 V
2. -6.6 V
3. 10.23 V
DC voltage at terminals Q319 between common ground and Q319:
1. 9.74 V
2. ≈ 0 V
3. 10.23 V
After installing the jumper between the negative terminals of the speaker and the primary ground, the DC voltage at terminals Q319 between the negative terminal of the speakers and Q319:
1. 9.74 V
2. -6.6 V
3. 10.23 V
Remove that transistor. Does audio return?
Those voltages should be identical. If they are not (readings in error), your jumper has a bad connection.
Those voltages should be identical. If they are not (readings in error), your jumper has a bad connection.
I deleted Q319, there is still no sound. I also removed the transistors Q101 and Q201, there is no sound. The jumper is connected on screws, so the contact should be good.
Have you operated all pots and switches through their entire range while listening for audio to see if it every played through (even just for an instant)?
Yes, I tried different modes for both channels. I have doubts about the two resistors R353(6,8K), R360(22 K). When measured without soldering them out of the board, they have the following readings:
R353 - 5.15
R360 - 7.9K
Do I need to drink them out to measure them correctly?
R353 - 5.15
R360 - 7.9K
Do I need to drink them out to measure them correctly?
With the muting transistors out of the circuit, if there is no audio, the problem is in the audio path. You'll have to trace it from the input RCA jacks to the driver ICs to see where it's being lost.
You can pull those and check them later if you still have issues when the three transistors are soldered back into the circuit.
You can pull those and check them later if you still have issues when the three transistors are soldered back into the circuit.
I have not tried to turn on an amplifier with three soldered transistors at once (Q101, Q201, Q 319), is it worth a try?
I'm not sure I understand the question. If you're asking if you should go back and test pots and switches (signal in and speakers connected) with those transistors all out of the circuit. Yes, that would be a good plan.
Good afternoon, sorry for not answering for a long time, there was no time. I found one damaged transistor Q318 2SB1076M, but I cannot find them on sale. Tell me what analogue it can be replaced with?
Was it open/shorted? It's a darlington so it may seem defective if you're checking with a meter.
https://alltransistors.com/adv/pdfdatasheet_rohm/2sb1076m_2sb1239.pdf
https://alltransistors.com/adv/pdfdatasheet_rohm/2sb1076m_2sb1239.pdf
Do you have any other darlington transistors on hand that you can test to compare readings?
You can build a darlington from the diagram on the datasheet to see if you get the same results when testing.
You can build a darlington from the diagram on the datasheet to see if you get the same results when testing.