STK2038B problems on my two Technics SU-Z55 ?

[fiero1]

Hello to all , this is my first post with a problem that bugs me for few months.
I have 2 Technics SU-Z55 ,on which both STK2038B (16 pins/legs) are supostedly broken on the left chanel ONLY ! Strangly the right chanel works with some knocking sound when I turn it on .
I read all of the post from previouse topics on STK2038 and SU-Z55 ,trayed most of the sugestions for replacing the STK ( I have 4 New STK from China 🙁 there are no new stuff becouse they are out of the buisness ) , also i replaise twisse the AN7062 , few resistors and some capacitors on the left chanel path ( I download the scematic ) , unsolder and checked both transistors 2SA992 (Q301-302 on the scheme) they shows good "beta" readings (492-541normal distance ) and at the end ...nothing.
The left chanel, when it is measured on the legs of the " IN " of the AN7062 chip , indicate high current and the display in front of the amp is also " full" , the right chanel is ok in that time , normal current on the IN ,so the AN7072 , which is beffore AN7062 works and nothing wrong whit him. He gives current to both left and right chanels.
Why with 4 different chips (STK2038B , of which 2 are Chinese brand new stuff and the other 2 are originals ) the result is the same ?
I have some knowledge in electronics but I have a colegue whose electronic skills are on profesional level and even he strugle ti find why these chips behave like that !!!
🙁
Can someone give some advice , what I have miss in the troubleshooting?
Here are some photos of the new chips and schematics.

Service manual download starting shortly

Thanks ,
Stefan

 

[JonSnell Electronic]

Check the DC voltages on the ICs. Check the components marked with a triangle with an ! in it in red, they are designed to fail when there is a problem and MUST be replaced with exactly the same type and value.

 

[fiero1]

Thanks for the fast reply !
The "red" marked resistors beffore these transistors Q301-302 are the same values as it is written in the schematic manual also both transistors 2SA992 are unsoldered and checked sepparetly in a transistor check device .
As for the STK2038B no one have the right datasheed for it ! I searched in all internet pages related to this key word and ...nothing.
So I don't know which leg represent IN and OUT and whose are the feedbacks ...
It is common error to mistake this chip with STK2038 || and thay have 22 legs ( I made that mistake once and bought the wrong one).
If someone have the datasheed for the "B" series with 16 legs and share with me ,I will be more than thankfull !

 

[fiero1]

I just opened the STK2038B (one of the broken once) just to trace the paths of the signals/current and based on what we have, me and my friend from work, will try to recreate the schematic or see which leg is what. 😉
These are the damaged transistors on the left channel :