Hi!
I'm trying to repair the Sony HCD-CP101 Hi-Fi equipment.
The problem is:
No audio output on the speakers.
Actually there is a very weak sound output on the speakers only if volume max.
It is a Hi-Fi equipment with a TDA7296 amplifier.
The volume is controlled by the LC75342 volume control ic.
What I was tried:
1. checked for shorten of the TDA7296 inputs and outputs - no short
2. checked for sound on the TDA7296 inputs whit a small speaker 8 Ohm 1w. - sound is hearing without any distortion etc.
3. until the TDA7296 checking by method 2 I tried to inc. decr. the vol. button and the sound on the speaker was correctly reacting.
4. checked the LC75342 ic voltages described in the datasheet of the Sony HCD-CP101 which I put the link at the end of this text for download.
5. checked the transistors:
Q815-Q818 - on the base should be 0v but there is 2.36v. if I play the CD than it should be 6.4v but there is 8v.
Q313 - on the collector should be 0v but there is 2.36v.
Q330 - on the collector should be 0v but there is 2.36, on the base should be 4.4 which is correct.
Q100, Q200 - on the base should be 0v but there are 2.36v.
6. I disconnected the CN501 and checked the transistors from the list above ( list index 5 ) again but the same result.
7. Transistors Q310, Q501 & Q502 checked for voltage as in doc described. Voltages correct.
8. Cut the trace on Q313 on the collector side & checked the collector for voltage, the voltage was 0V but on Q200 base was still 2.3V.
9. Changed the TDA7296 with new but no result.
I have no clue what could be the problem.
Any help would be nice.
I missing something in my repairing but I cant see it.
Here you can download the Repair manual for this device:
https://mega.nz/#!dtdmkKZQ!sX27M022_ZG2Ek7YUCFilRyIHnDkfQUaVtKYYfDEcKQHere is the link for the TD7296:
http://www.st.com/content/ccc/resource/technical/document/datasheet/3a/2f/b7/86/30/b2/4b/6c/CD00000198.pdf/files/CD00000198.pdf/jcr:content/translations/en.CD00000198.pdfI focused on the page 25 & 26 in the repair manual and all testing was done
as it is described in the repair manual at that pages.
Equipment was ON in tuner mode.
I hope for somebody to give me a helping hand.
Thanks and my best regards.