VT30 Problem - Loud Hum

[Gareth]

Hi,

I've owned a Vox VT30 for just over a year, working perfectly for all that time. The amp had made the journey from Cornwall to Uni near London and back again, working perfectly after each trip. However, after returning to Uni again, the amp, when turned on, has made a continuous tone whenever switched on, not affected by ANY controls, as shown in the video below:
http://s1164.photobucket.com/albums/q57 ... tarAmp.mp4
I have opened the back of the amp to have a look. I'm not an expert in electronics, but nothing looked broken or unwired. I've followed some advice I got on the Vox forums, namely hitting it, testing the tube is fully in, jiggling the wires whilst it hums in an attempt to see where the faulty area is, and reseting it. With headphones plugged in, the amp continues to make the hum through the speaker. Does anyone have any idea as to what might be wrong, or whether there is anything I can to do affect repairs? Any help is appreciated.

[retrobob]

Does the amp work through the headphones?
This will tell us if the pre-amp section is working.

If the amp works through the headphones with the buzz still present, check the headphone plug connection at the lower circuit power board, make sure it is inserted completely.

headconnect.jpg (211.67 KiB) Viewed 137 times

Next, unplug this connection at the lower board and test to see if the buzz is still present.

If the buzz is gone with it unplugged chances are the headphone circuit board is damaged, we have a test circuit available to confirm this and we have replacement INPUT/HEADPHONE circuit kits to fix it;
http://www.valvetronix.net/forums/fx-loop-mod-member-discount-how-to-order-kits-t3907.html
scroll down the page to the VT section

If it is still buzzing with the headphone board unplugged, it needs a trip to the tech.

[Gareth]

The amp works through headphones. With that plug unplugged, it still makes a buzz. Thanks for the help, anyway.