I'm not sure what is wrong with this amplifier, it Powers up and has a different curcuit than the cxa amplifiers. There is no output at the speaker terminals.
Boost converter, signal positive rail. The rail should be around ~80-85v. Also check the +/- 17 volts at Q22 and Q23 regulators.
Check to see if you have oscillation at both output coils L101 and L201 which should have a 50% duty cycle and ~80 volt swings.
Use Power Ground for Black probe or scope Ground.
Check to see if you have oscillation at both output coils L101 and L201 which should have a 50% duty cycle and ~80 volt swings.
Use Power Ground for Black probe or scope Ground.
The input board was badly damaged. Corrosion badly effected the components. I did the best I could to remove and rework the board. Same result, push 40hz 5v in and on the output jacks no signal? There maybe components missing.
Your oscope pixs show a good amp, the input board is most certainly the problem.
The input board looks rough. Have you tried to signal trace through the input board?
I will get pix of good input board and study schematic to see if your board has any missing parts.
If you can get your hands on another KX8001, KX12001 or KX16001 any one of these amps uses the same input board.
The input board looks rough. Have you tried to signal trace through the input board?
I will get pix of good input board and study schematic to see if your board has any missing parts.
If you can get your hands on another KX8001, KX12001 or KX16001 any one of these amps uses the same input board.
The input board is what I also suspected from the beginning. I fixed most of the soder joints as best I could but it's still very bad. I can try to signal trace it back. I know that it doesn't reach the output just. C101,102 or C202 are missing. Alot of the capacitors or resistors are bad either I cant get a reader or soder the ends anymore they are missing the solder caps.? C205 is a value I need.
Last edited:
C101,102 and C202 are not populated. C205 is a 22pF.
I tried to post a picture of input board but not having any luck. I will try again later tonight.
I tried to post a picture of input board but not having any luck. I will try again later tonight.
I have a friend that has one of these amplifiers he is going to let me use it to repair this one. I will be able to directly check the board vrs mine until it functions as intended.
If you don't have one, get a Dr. Mom otoscope from walmart to examine the tiny traces on the board, if any are corroded.
Got the input board working. Replaced almost everything. Anyway, now when i turn the amplifier off there is an audible thump coming through the subwoofer. What would be causing that?
There may be an issue with the muting circuit. Check around Q19,Q20,Q21. The header pins near Q19 look to be damaged.
It occurred to me you had a good input board from a friend. If when testing with that board, do you have the same turn off pop?
It occurred to me you had a good input board from a friend. If when testing with that board, do you have the same turn off pop?
Attachments
Last edited:
Everything in that area looks good and is now touched up. Zd9 seems to be not functioning properly.
What transistors can be used in place of the three in the muting curcuit. I'll replace them and see if that helps.
Apologize for the late reply. Any general purpose transistor will do for testing. Just be sure to account for pin outs and polarity.
The BC807 and BC817 can be found through Mouser.
Where you able to use the known good board from your friend to isolate the problem to the input or main board?
The BC807 and BC817 can be found through Mouser.
Where you able to use the known good board from your friend to isolate the problem to the input or main board?