Technics SU-V5 won't turn on (2)

Thread Starter

simoneg80

Joined Apr 29, 2024
4
good morning everyone, I also have a beautiful SU-V5 and I'm trying to repair it, I just have a general problem, and I humbly ask you for help, for now this wonderful discussion has helped me to stop blowing the fuse like the sigoner of the post, I desoldered the 4 transistors Q331, Q332, Q333, Q334, verified and I noticed that the Q331 (C2581) is broken, while the others are not shorted and with the multimer they seem ok.
I did the readings with the testers as you asked the gentleman and the data is as follows in the photo, can you help me understand if it is ok or if there is something wrong?
Thank you all

Moderator edit: New thread created from this.
 

Attachments

Last edited:

Thread Starter

simoneg80

Joined Apr 29, 2024
4
I apologize and thank the moderators for creating the new discussion, I also list other problems that the Technics had (but the music still worked)
1) resistors caught on fire R404; R403; R402
2) Speaker switching relay not tripping when I turn speaker selector, but sound came out
3) unfortunately just now I broke a transistor with my hands, the Q603 displays the writing 2sc1384nc, and the relay does not trip as soon as the amplifier is turned on, if I place it on the 3 contacts the relay turns on.

To make things easier I am attaching photos of my amp with exploded resistors and photos of another amp Technics SU-V5 in good condition, not mine but the same with healthy resistors.
 

Attachments

Dodgydave

Joined Jun 22, 2012
11,360
The relay pulls in because there is voltage on the speaker outputs ,so one or more of the output transistors are faulty or the drivers are.

Do you have the service manual?
 
Top