Tektronix 222 Repair

[Simonv92]

Hi All!
I have a Tektronix 222 scope that doesn't work. It won't startup.
Battery is dead so I'm powering it with the external jack with a bench supply set to 14V.
When I apply power the Trigger led blink for a second and I can hear a "beep", after that nothing happens. Doing some test on the Power Supply Board (A4) I've found that the power FETs that drives the main transformer becomes very hot (the unit in this state draws about 12W of power so there's something wrong).
After some tests I've isolated the 120V line after the transformer, now the scope draws less power and the FETs stays cool but I can't make it work.
I'm using the 222A service manual which include boards schematics, they are not exactly the same but pretty similar: https://www.eserviceinfo.com/download.php?downloadstart=1&fileid=70093
In the troubleshooting procedure guide I've read that the pin 13 and 14 on the TL594 on the Power  supply board should stay near 0V in normal operation, on mine they always stays at about +5V.
I think taht something isn't working properly on the power supply board but I can't find what.
Do you have any idea? Any help will be appreciated!
Thank all!
Simone

[jxjbsd]

Go to https://groups.io/g/TekScopes search, maybe there's an answer