Philips PM3050 oscilloscope failure

[BChT]

Hello everyone! I recently bought my first scope philips pm3050 and it was advertised as tested and fully functional. However now, when it arrived i noticed it has broken of potentiometer and also the handle is stuck on in one position and therefore i can't tear it down. I tried to turn it on, but it makes weird high pitch noise and both the crt and the lcd don't turn on. I checked the resistance on the mains connector and it's 1MΩ. I don't know if I'm doing something wrong, because it's my first scope, but it seems like it's faulty. Please tell me if you know what it could be, I'm not sure if I can repair it, but I can try.

[TrendX]

You can adjust the handle by pulling it away from the case on both side for a few millimeters. This reveals the locking pins and allows it to rotate.

The buzzing noise most likely comes from the input filtering caps on the power supply. I had the same problem with mine a few months ago and fixed it by just replacing these 3 caps.

EDIT:
User manual: https://www.allaboutcircuits.com/test-measurement/oscilloscopes/pm-3000-series-3050/manual/

Service manual for the 3055 which should be near identical: https://www.qsl.net/vk5bar/AHARS-Resources/Philips%20PM3055/PM3055%20Service%20Manual.pdf

[BChT]

Thank you for help, i think i will replace those caps and it should be fine.

[richipedia]

I have had 3 PM3050/PM3055 in total now.
The power supply makes this buzzing sound if one of the outputs is shorted.

One reason for that may be that one of the buffering caps failed short.

Another reason is the following: the power supply has an overvoltage protection for the +5V rail. Also, there is some kind of overload protection stated in the service manual. If one of those two fault conditions occur, a crowbar circuit is activated, which shorts the +48V and -48V rails.