Here is picture showing position of damaged Ultrasonic and Relay.
It was not hot at the sealing point and motor no.2 in the picture not worked at first. After replacing the ultrasonic box, it worked for about 20 minutes then broke down. We took a box from other place in the same machine to replace but it worked for only 10 minutes. We saw burnt mark on the relay so we replaced a new relay then it worked for a while and again burnt mark on the 2nd relay. Replaced with the 3rd relay, it worked but with electric spark at relay contact then the 3 box has gone.
So we have completely stopped the machine waiting your comments to resolve the problem.
Thank you,
Charoen