I have a Kenwood KAC848 amp with the rail voltage fluctuating from about 28v to 33v. The 494 chip has many pins also going up and down. I will list the pins below. Please let me know where to start with this.
thanks Jeff
494 pins
1. 2.5 - 2.7v
2. .8 - 2.5v
3. 4.8 - 1.8v
4. .63
5. 1.69
6. 3.7
7. 0
8. 14
9. 0 - 4v
10. 0 - 3.7v
11. 14
12. 14
13. 5
14. 5
15. 5
16 0
thanks Jeff
494 pins
1. 2.5 - 2.7v
2. .8 - 2.5v
3. 4.8 - 1.8v
4. .63
5. 1.69
6. 3.7
7. 0
8. 14
9. 0 - 4v
10. 0 - 3.7v
11. 14
12. 14
13. 5
14. 5
15. 5
16 0
Is there any DC voltage on the speaker terminals?
Is the amp drawing excessive current (more than 2 amps)?
Is the amp drawing excessive current (more than 2 amps)?
Hi Perry
Yes, I am getting 1.8vdc to 1.89vdc on the outputs
the amp only draws at most 1 amp
This is with no signal running through it.
Thanks Jeff
Yes, I am getting 1.8vdc to 1.89vdc on the outputs
the amp only draws at most 1 amp
This is with no signal running through it.
Thanks Jeff
Have you checked the output transistors to determine if any were shorted?
For the following, the meter will be set to DC volts and the black meter probe will be on one of the non-bridging speaker terminals.
Do you have positive voltage on the center leg of D11 and negative voltage on the center leg of D12?
Do you have either positive or negative rail voltage on the center leg of each of the output transistors?
Do you have both positive AND negative voltage on the power supply pins of each of the op-amps?
For the following, the meter will be set to DC volts and the black meter probe will be on one of the non-bridging speaker terminals.
Do you have positive voltage on the center leg of D11 and negative voltage on the center leg of D12?
Do you have either positive or negative rail voltage on the center leg of each of the output transistors?
Do you have both positive AND negative voltage on the power supply pins of each of the op-amps?
The outputs don't seem to be shorted. D11 has positive voltage going from 22v to 33v and D12 has negative voltage going from -22v to -33v.
The 2SA1908's have negative rail going from -22 to -33v and the 2sc5100's have positive rail going from +22v to +33v.
I connected a signal and the amp will turn on and work good for about five minutes. then turn off for about ten minutes. the readings are from when it turns off. when the amp is on the rail voltage becomes steady.
The 2SA1908's have negative rail going from -22 to -33v and the 2sc5100's have positive rail going from +22v to +33v.
I connected a signal and the amp will turn on and work good for about five minutes. then turn off for about ten minutes. the readings are from when it turns off. when the amp is on the rail voltage becomes steady.
When the amp is working normally, if you push on the board at various points with a non-conductive probe, can you make it shut off?
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