Many suspects for a no sound in CD player repaired. Model Safa CD-21
A German organization nearby brought me a CD player for repair. The main symptom was no sound. In my mind, I thought it was an easy repair but, it was completely a different story.
This is the name brand of the CD player.
It was a China made CD player and when I searched it on line; I could not find any information about this brand name.
More specs are found on a sticker under the CD player itself. It can play back many inputs including a USB input.
I wanted to test the CD player before doing any kind of repair on it so I put a music disk on and sure enough, it read it and started to play the music. It confirmed what the customer said because I could not hear any kind of music even when I put the volume up.
A few screws off and I was able to get inside the device and as you can see, not much inside of it. Another three screws to come off and I were able to flip the board to see what lies beneath.
My suspect area was well known to me and directly I started working in that section of the board. I measured voltage going to the IC and sure enough there was about 12 volts going there and based on that this IC became my main suspect. I wish I had an oscilloscope to check the Audio wave on it but sad to say I do not have one.
My main suspect IC part number was TA8227P. I have a part just like that in my parts box and sure enough I soldered off board and directly replaced it. You can click on the datasheet photo below to view the information:
Sad to say, that did not fix the no sound problem in this device.
I started checking the capacitors with my ESR meter to look for capacitor that had a high ESR reading and I found only one. It was 470 UF/16 volts.
That did not help me resolve the problem so I kept searching for an answer.
I started heating up parts with my soldering gun and I came across some interesting thing. The moment I touched the center pin of the IC which was ground, the sound came on nice and clear. The moment I shut down the CD player and turn it on again, the sound was gone and we are back to the same issue.
I decided to take the IC off board and see and check round it for SMD parts that I missed when I was checking before.
I found an interesting thing hiding between the first pin of the IC and the leg of the capacitor. It was marked 100 on the SMD part which means it is only a 10 ohm resistor. When I measured it with my multi meter, it was giving me 75 Ohm. I soldered off board and tested it again and it gave almost the same result. It was an SMD resistor that went up in value.
I hope you can see that tiny SMD resistor.
The moment I replaced that bad resistor with a good one, the sound was restored in this CD player. Not back for China made CD player.
Mission Accomplished.
This article was prepared for you by Waleed Rishmawi, one of our ‘Master Authors’ and currently working in the Bethlehem area of Palestine repairing electrical and electronic equipment.
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albert van bemmelen
November 27, 2018 at 9:53 pm
If we not even can trust the ordinary common passive components, it will make any repair so much harder! So good job!
Waleed Rishmawi
November 28, 2018 at 6:40 pm
Albert: thanks man.
Parasuraman S
November 28, 2018 at 12:19 am
Vow! That was an excellent fix of an extremely difficult to find trouble! Shows your sagacity!
Waleed Rishmawi
November 28, 2018 at 6:42 pm
Parasuraman: it took me a while but it was a time well spent..
moshe
November 28, 2018 at 6:26 pm
Sheesh Waleed, that was one really excellent fix. And one that i will be sure to remember!
thanks for sharing it.
Waleed Rishmawi
November 30, 2018 at 9:56 pm
Moshe: thank you very much. have a blessed day
Yogesh Panchal
November 29, 2018 at 4:27 pm
Good Investigation! Waleed,
Waleed Rishmawi
November 30, 2018 at 9:57 pm
Yohesh: thank you very much. have an blessed day
Devon Wilson
November 30, 2018 at 5:16 am
Thanks for sharing Mr. Waleed. I do understand that not having a scope can make things difficult, not being able to trace signals in and out of an IC to determine its integrity.Also, I understand that you might have seen that sort of problem before and thus you concluded that the audio processing IC was defective. You measured 12v on presumably VCC which is labelled as 9v operating voltage. This to me would suggest that the IC was not loading the circuit down. Also, you did not mention the measured voltage on the output pins.
Waleed Rishmawi
November 30, 2018 at 10:01 pm
Devon: you are most welcome. yes, I have seen this problem before and based on that I found the answer to the problem.
ThandoSebeneleMavimbela
April 3, 2019 at 3:13 am
Wow amazing l wonna say thanks now am not the same am grow