Hello, Sergey!
 SV> there is a problem with %subj%. It plays high frequencies very bad
 SV> and
 SV> dirty. I thought that heads became dirty and magnetic, so, I've cleaned
 SV> them up and demagnetized, but it didn't help me! ;(
You didn`t say if this problem is actual only for the cassette deck or the 
sound of tuner, for example, is corrupted too? And if the deck works badly, 
can you say it about both slots, or one slot for tape is ok?
The most likely case may be the problem of incorrect azimuth. I mean the 
angle between magnetic heads and the axis of tape-moving. It is pre-justified 
on the factory where the system is built but after a while, especially if you 
have reverse on your deck, it de-justifies and head invisibly turnes a 
little. This always causes the losses in high frequencies and balance 
problems. All you have to do is to find a way to turn a small screw (there 
might have been two screws, if there`s a reverse mechanism, for each way of 
tape moving as on my TECHNICS RS-TR 373 deck) under the magnetic head. This 
screw justifies the head azimuth. Usually on SONY mini systems you are able 
to take the cover of cassette slot out- and watch this screw(s) under the 
head. On some JVC decks I`ve seen the small hole under the cassette slot, 
where to put the screwdriwer. Just put in a cassette (with some high freqs 
sure), press the play button and try to turn this screw with screwdriver and 
listen- if you see the frequencies becomes more poorer, turn the screw to 
another side, and watch the difference. I myself always justify the azimuth 
to any new cassette (not recorded on my system) because I feel the sound is a 
little bit grey without the fine azimuth adjustment.
Hope you`ll solve your problem.
Bye!
    Dennis
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