I got this AVR for 24 euros and tried to fix it as a fun and learning project.
First the audio video receiver would turn on but had no sound at all.
So, I opened the metal case and noticed some liquid damage marks. Those marks were found on the main board and the digital board.
I disassembled everything, checked every single cap on every board of the amp and recapped when needed.
Also fixed A LOT of cold solder joints and also done some modifications, I added heatsinks on linear voltage regulators, both on the main board and the digital board that were obviously overheating.
I also put a blob of thermal pad under the main board under the main IC201 sound processor because it also overheated.
After cleaning the PCB and doing all the above work I connected it and found that it now works except from the digital board.
When in 2 channel mode it works normally, checked all inputs and they all work and also checked all the amplifier outputs and they also work.
To check all the outputs used the 5.1 CH analog input that bypasses the digital board.
So everything works until I try to adjust the bass or tremble or enable a sound-field, then the amp goes silent, because the digital board kicks in.
Also the digital inputs don't work. But the dolby digital /DTS/PCM 48KHZ input data are properly recognized and shown on the display.
So, after doing some tests and examining the digital board schematic I concluded that the AK4527VQ was dead and ordered replacement from aliexpress. The replacement arrived and I soldered it on digital board but nothing changed. Does anyone know how to find out if I got a faulty IC or maybe I misdiagnosed the fault?
The digital board of this amp is really simple due to cost cutting and very easy to understand. Can someone advise how can I rule out the replacement AK4527VQ being faulty?
I also have a digital oscilloscope and could use it if needed.
First the audio video receiver would turn on but had no sound at all.
So, I opened the metal case and noticed some liquid damage marks. Those marks were found on the main board and the digital board.
I disassembled everything, checked every single cap on every board of the amp and recapped when needed.
Also fixed A LOT of cold solder joints and also done some modifications, I added heatsinks on linear voltage regulators, both on the main board and the digital board that were obviously overheating.
I also put a blob of thermal pad under the main board under the main IC201 sound processor because it also overheated.
After cleaning the PCB and doing all the above work I connected it and found that it now works except from the digital board.
When in 2 channel mode it works normally, checked all inputs and they all work and also checked all the amplifier outputs and they also work.
To check all the outputs used the 5.1 CH analog input that bypasses the digital board.
So everything works until I try to adjust the bass or tremble or enable a sound-field, then the amp goes silent, because the digital board kicks in.
Also the digital inputs don't work. But the dolby digital /DTS/PCM 48KHZ input data are properly recognized and shown on the display.
So, after doing some tests and examining the digital board schematic I concluded that the AK4527VQ was dead and ordered replacement from aliexpress. The replacement arrived and I soldered it on digital board but nothing changed. Does anyone know how to find out if I got a faulty IC or maybe I misdiagnosed the fault?
The digital board of this amp is really simple due to cost cutting and very easy to understand. Can someone advise how can I rule out the replacement AK4527VQ being faulty?
I also have a digital oscilloscope and could use it if needed.
Replace it again, but use a more reliable vendor.
Two bad ones in a row are unlikely, unless they are from aliexpress.
Two bad ones in a row are unlikely, unless they are from aliexpress.
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It was from aliexpress.
The problem is that it is not available from reputable sources since this is an old and discontinued codec IC and on ebay it is so expensive that the amp is not worth it. I could connect the multichannel analog outputs of a desktop pc (or laptop with external sound card) to the amp 5.1 analog input and get away with it.
Or even get something like this:
https://www.aliexpress.com/item/100...!sea!GR!1713572179&curPageLogUid=yAkMmqPhoTkO
The problem is that it is not available from reputable sources since this is an old and discontinued codec IC and on ebay it is so expensive that the amp is not worth it. I could connect the multichannel analog outputs of a desktop pc (or laptop with external sound card) to the amp 5.1 analog input and get away with it.
Or even get something like this:
https://www.aliexpress.com/item/100...!sea!GR!1713572179&curPageLogUid=yAkMmqPhoTkO
If you got it as a declared fault unit, I have a har time seeing it as being "scammed" if it didn't work / was damaged.
Good luck with the repair!
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Good luck with the repair!
//
The amp I got it for parts / faulty / need repair. And it now works except the digital board so I am already quite happy with that deal. But the codec IC I ordered from aliexpress was described as working but it didn't work
Only other thing could think of.
Is power supply to the chip
or likely whatever pins go High/low etc etc
to turn the chip on are not functioning correctly.
Or whatever controls the audio routing from the chip.
Fet , relay , switch etc etc
The chip could be fine possibly.
just the associated circuits to turn it on
or route the signal are not
possible fets or transistor circuits remain high/low
from faulty device or no power. failed transistor
or board connections. Likely near the liquid damage
area. Or damage shorts etc in liquid damage area
caused components elsewhere to fail
in all simplicity double check pads or traces
to chip if lifted or any solder bridges hiding.
with magnify glass
Is power supply to the chip
or likely whatever pins go High/low etc etc
to turn the chip on are not functioning correctly.
Or whatever controls the audio routing from the chip.
Fet , relay , switch etc etc
The chip could be fine possibly.
just the associated circuits to turn it on
or route the signal are not
possible fets or transistor circuits remain high/low
from faulty device or no power. failed transistor
or board connections. Likely near the liquid damage
area. Or damage shorts etc in liquid damage area
caused components elsewhere to fail
in all simplicity double check pads or traces
to chip if lifted or any solder bridges hiding.
with magnify glass
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Found the problem... The CNP103 connector was not fully inserted for some reason. Made sure it's totally in, retried and the amplifier now works perfectly fine!
I can set tremble/bass, enable digital effects, also tested it with dolby digital / dts / pcm source and it worked without any issue.
So the Chinese replacement CODEC IC was fine. Already left positive review for the item/vendor. That doesn't mean that the IC I bought is genuine but I could care less about that since it works.
Unfortunately there is no way to tell if I replaced the original AK4527 without reason, since I am not sure what happened to the CNP103 connector and it was found not properly inserted.
There is a chance that the orginal CODEC IC was OK and the connector was out all that time.
The CNP103 connector is located on the display board and in order to check it you have to remove that board from the amp.
Thanks to everyone for their valuable input!
I can set tremble/bass, enable digital effects, also tested it with dolby digital / dts / pcm source and it worked without any issue.
So the Chinese replacement CODEC IC was fine. Already left positive review for the item/vendor. That doesn't mean that the IC I bought is genuine but I could care less about that since it works.
Unfortunately there is no way to tell if I replaced the original AK4527 without reason, since I am not sure what happened to the CNP103 connector and it was found not properly inserted.
There is a chance that the orginal CODEC IC was OK and the connector was out all that time.
The CNP103 connector is located on the display board and in order to check it you have to remove that board from the amp.
Thanks to everyone for their valuable input!