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Sony CD/Cassette/Radio set fix, bad caps again..HCD EP40

My sister came walking in with her small Sony Radio/Cassette/CD-player.
Of course there was a problem with this device



The volume control was not working, when at "0" it would mute, but at low level it would just go too loud.
Luckily I found a schematic online : http://diagramas.diagramasde.com/audio/HCD-EP30%20EP40%20sm.pdf



After some investigation I figured out that the LC75392 was in control of the volume http://pdf.datasheetcatalog.com/datasheet/sanyo/ds_pdf_e/LC75392.pdf

I traced the problem to the main circuit board and started measuring all the voltages (given in the schematic) and they appeared to be all right.

I then used my new audio-sniffer to track the audio from the radio receiver.
http://www.openmusiclabs.com/projects/audio-sniffer/ This is where I got one from Santa-Claus.



Some example of someone else tracking a signal with the audiosniffer here on YouTube.
http://www.youtube.com/watch?v=ZxUItbtYl_0

I noticed that I was getting a lot of signal on the ground reference (pin 18, which should be virtual ground without audio noise)


In the picture I made the virtual ground a yellow color.

Looking at the schematic I found the usual suspects, the capacitors, C238 and C202 both 470uF/16V and both where completely dried out. So I replaced the caps with some others I had within reach (2200uF) and Hooray !! It works again.

If you find this useful please send money to this BitCoin address : 1DynDMhxWweJr6aoSZXUzenJMkSjaWHGxo

A picture from the bottom of the circuit board after replacing the bad caps.




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Locatie: Best, The Netherlands

Reacties

Unknown zei…
Thanks Edwin from Estonia !

Cheers :)
Sergo
dinsdag 16 september 2014 om 15:01:00 CEST
Unknown zei…
Thank you for this information.
Solved my problem.
Italy
vrijdag 29 december 2017 om 16:01:00 CET
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