TDS3054 Synchronization trigger repair

[Aldan]

Hello to all!

Who knows, please tell me how to repair the synchronization trigger of the TDS-3052?
Where is this synchronization trigger, which signals is controlled.

It keeps synchronization only near the maximum amplitude of the signal (sine or rectangle).
Only 5-10% of the maximum.
I changed to new chips: MM9577-ACE; MM9595-VUW; MM9576-VJG and even from despair C8600DCZP33C1 and so on trifles.
Everything remained unchanged, that is, there are no new faults, except this one.

Respectfully,
Aldan

[ArcticGeek]

Unfortunately there are no schematics for these scopes that have been released to the public, so it's difficult to know where to look.

I am curious though - where did you obtain the replacement parts for the unit you were trying to repair?   Did you buy the parts new?