How to know the integrated model

[RCoto]

I have an integrated one of an ultrasonic washing machine.

This when measuring its frequency oscillates in 80kHz, but after a few minutes it begins to decrease the frequency and increase uncontrollably, so I have decided to change it.

the question is that where the model should appear is torn and can not be seen, but below shows this information.

S "Tear" A (only the letter "S" is displayed at the beginning and the letter "A" at the end)

V6 FG675

CHN99614

I will attach an image.

I hope you can help me.

Thank you.

[BRYAN SPEED]

schematic ? try the old tracing out by hand of the connections, make some sort of schematic. scientific wild guesses can follow :) info on chip not traceable to the part number