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Question Panasonic SA CH11

shdam1

Junior Member
Mar 10, 2021
4
0
6
I have bookshelf music system Panasonic SA CH11. It started to behave in a strange way. None of the buttons work now. It switches on. The display shows random modes. Some times it shows ERROR. Sometimes the CD tray opens and closes by itself. Can someone please help me to understand what exactly is the issue.
 

mindless1

Diamond Member
Aug 11, 2001
6,288
759
126
Without knowing anything specific and unique about their design, I would grab a multimeter and test whether the power supply section is outputting the correct voltages and look for signs of failed components. If you are not experienced and comfortable working around live, mains powered equipment then this may be something to take to a repair shop instead of DIY.

I'd also examine the button PCB for hairline cracks, check continuity of the traces on it, or whether there is a slot/bracket/something that PCB sits in that has broken so the switches are not being fully depressed when their outer corresponding plastic buttons are pushed.
 

shdam1

Junior Member
Mar 10, 2021
4
0
6
Without knowing anything specific and unique about their design, I would grab a multimeter and test whether the power supply section is outputting the correct voltages and look for signs of failed components. If you are not experienced and comfortable working around live, mains powered equipment then this may be something to take to a repair shop instead of DIY.

I'd also examine the button PCB for hairline cracks, check continuity of the traces on it, or whether there is a slot/bracket/something that PCB sits in that has broken so the switches are not being fully depressed when their outer corresponding plastic buttons are pushed.
Hi,
Many thanks for the reply. I had changed the power supply filters to rule out power issues. Voltages are fine and correct as per the service manual.
To rule out switch issues I had totally disconnected all switches . It's just two resistors that connects switches to the microcontroller. I then cleaned all connectors to rule out connection issues. Changed the ossilators of micro controller. Checked the pins of microcontroller with magnifier for any possible minute short . Cleaned all PCBs with alcohol to rule out dust interfearing the signals. Even changed the jog dial to rule out improper pulses.
In the end nothing changed.😀
 

mindless1

Diamond Member
Aug 11, 2001
6,288
759
126
Oh, you have a Service Manual? I would like to help more, but there is only so much I can guess about without leading you on a wild goose chase since I don't have the unit in front of me, and if some controller is fried, might not be able to figure it out even if it were in front of me without more knowledge than I have about these units.

Highly integrated units can be a PITA, is one reason that I, like people who build classic cars, like to keep them simple and in the case of audio, build a separate amp that isn't married to the input sources. You don't get a fancy display or remote that integrates *everything* that way, but then when something goes wrong, easier and less expensive to replace modular components.

You could try asking for help at one of the electronics forums, for example this one:

As far as your CD tray opening and closing, it might be a bit controversial but I would pull the entire CD mechanism out of it, and instead, get one of those inexpensive USB/mSD, MP3/flac/etc audio player modules on ebay/etc, tap into a low voltage rail off the PSU to provide 5V through a linear regulator like LM7805 to it, and use its output into the existing line level input from the CD player you removed. Just saying that CD players.... meh, when you can fit an entire bookshelf worth of CDs on a tiny mSD card, they have outlived their usefulness except as an archive media.
 
Last edited:

shdam1

Junior Member
Mar 10, 2021
4
0
6
Oh, you have a Service Manual? I would like to help more, but there is only so much I can guess about without leading you on a wild goose chase since I don't have the unit in front of me, and if some controller is fried, might not be able to figure it out even if it were in front of me without more knowledge than I have about these units.

Highly integrated units can be a PITA, is one reason that I, like people who build classic cars, like to keep them simple and in the case of audio, build a separate amp that isn't married to the input sources. You don't get a fancy display or remote that integrates *everything* that way, but then when something goes wrong, easier and less expensive to replace modular components.

You could try asking for help at one of the electronics forums, for example this one:

As far as your CD tray opening and closing, it might be a bit controversial but I would pull the entire CD mechanism out of it, and instead, get one of those inexpensive USB/mSD, MP3/flac/etc audio player modules on ebay/etc, tap into a low voltage rail off the PSU to provide 5V through a linear regulator like LM7805 to it, and use its output into the existing line level input from the CD player you removed. Just saying that CD players.... meh, when you can fit an entire bookshelf worth of CDs on a tiny mSD card, they have outlived their usefulness except as an archive media.
Thanks again. 😂😂In fact to be honest I have purchased one such Bluetooth board. I decided to give this 'vintage'thing a try and get it back to life. If it's not going to happen,then my plan was to proceed as you have mentioned- just to make use of the amplifier section. Do you feel the microcontroller is the culprit in this?
 

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mindless1

Diamond Member
Aug 11, 2001
6,288
759
126
I have insufficient info to determine that. All I can suggest is to do what i already mentioned. BUT, there is more to it.

If you understand power amps, you can trace the circuit, the ac audio signal in and out of the power amp stage, but you seem to have at least one other problem that is outside the scope of doing that.
 

shdam1

Junior Member
Mar 10, 2021
4
0
6
I have insufficient info to determine that. All I can suggest is to do what i already mentioned. BUT, there is more to it.

If you understand power amps, you can trace the circuit, the ac audio signal in and out of the power amp stage, but you seem to have at least one other problem that is outside the scope of doing that.
Yes. Let me keep trying. I will update you if I succeed😀. Many thanks for your time.
 
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