Double deck cassette player/recorder with 4-band radio and line input.
I hadn't found schematic for this model, but service manual for similar model, MW738L is available.
FM band range: 65 - 108 MHz.
SW range: 6 - 18 MHz. Fine tuning regulator on the side.
+ medium wave and long wave ranges.
"Surround" seems to be cheap gimmick with phase shifted signal.
First and easy to fix problem: tuning mechanism jammed with lot of lint.
Second problem: broken trace on volume potentiometer, resulting in much higher volume in left channel. At first I've tried to use solder to fix, but this metal trace was not solderable and heat from soldering iron only damaged it more.
I've tried to made myself conductive glue with carbon (pencil) and with copper, but results were dissapointing. Thus I've bought cheap (~$1) 0.2ml "silver" conductive glue from ebay or aliexpress:
Not beautiful, but it works. One surprising thing is that this glue is conductive only after drying.
Another issue, only partially fixed was weird problem with DC component and some brum in left channel. It seemed to be related to function switch and reassembling and cleaning it helped a little. Funtion switch does not to be reliable and also seems to generate some crackling noise in Line In mode. I'm still not certain what is real problem here, but as tracing it took a lot of time and brum volume is rather low I've pass on it.
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