Sharp GF-575E Audio Distorting pick up failure

[Christopher1389]

Did you verify that all of the new caps are installed correctly +/- ?
Are those fusible resistor on that board, if so, did you check them?

Yeah I checked time and time again it almost sounds like a transistor issue or ic I didn't check those tho so I will get back too you with that

 

[Superduper]

If I were you, I would carefully desolder the HA1392 chip from the board, clean off the old, probably dried up heat sink compound, clean off all the corrosion from the pins, and reinstall with fresh heat sink compound. Audio that is unreliable and or cuts off after some time in operation could be from unreliable connection (corrosion) or from the chip over-heating from poor heat transfer to the cooling radiator. If you decide to do this, on reinstallation, first install the chip onto the heatsink with the tab screw to fix it in place, then install the heatsink and fasten it (if it is fixed in place with fasteners) and lastly, solder the pins in place. If you solder the pins before installing the heatsink, you'll risk the tab not being tight against the heatsink, or the screw tweaking the chip when torqued down. Also careful examination of solder pads should be performed or just touch up all of them.

 

[Huffers]

Thanks for the advice @Huffers so before I went on vacation I did just that I isolated the amplifier from the tuner and cassette deck and still get the same sound. I then tested the transistors Q181 q183 Just because they are in the path or the audio or circuit
And they tested all OK. So my Suspicion now is the dolby chips TA-7629P But unfortunately, I don't have the datasheet for them

so I tested them and one side doesn't read at all pin 9 10 11 13 14 15 16 and pin 12 is grownd is this right I haven't tested a ic before ? The gray line going into pin 4 is the Playback signal

That doesn’t sound right to me. The circuit diagram shows the voltages that you should have at each pin relative to ground. Also pin 12 should have 6v according to the diagram. Shouldn’t be grounded as it’s connected via a capacitor to ground, the capacitor should be open circuit so it shouldn’t show ground. Check that capacitor because that could be pulling it down.