Troubleshooting Tuner ST-S550ES

[helios999]

My ST-S550ES sound good five minute then the ssound is dirty .
if i change the frequency manually and i tune to the same frequency , it sound good but for few minute !

it's not easy to hear some music !

a little help
thanks

[helios999]

i have ths manual service

here the shematic

[Mooly]

Being able to retune, and it then being OK suggests more of a misalignment issue to me.

Is there any mention of an AFC adjustment in the manual. Don't twiddle anything, but if any of the cores in the transformers are adjustable see what just placing a metallic trimmer in the core does as that alters the tuning without you twiddling. See if the sound come back.

[helios999]

AFC ?


a manual service

thanks

[Mooly]

It's T301 and T302 on the circuit diagram.
RF work is so difficult and requires specialised gear so anything you alter is at your own risk
Any feritte cores need the correct tools to adjust them (you can make them by filling suitable nylon or plastic material). If you try and use a small screwdriver that doesn't fit they will crack very very easily.

And I'm just "guessing" that this would hopefully correct the problem. Try what I said earlier and try and alter the tuning of the coils by placing a metallic driver "into" the cores without turning them. Also putting fingers on and around the PCB and components in that area might give you an idea... very non scientific but it works.

[helios999]

I have adjusted T301 and T302 , and it sound good now

thanks Mooly

[Mooly]

Your welcome.
Pleased you were able to fix it.