I have just finished a K4040 kit. When doing the setting up I noticed that LED12 lit on standby and powered. I foolishly continued and added the 3 small valves and then measured the voltages. The 335V and 110V read low at 312V & 88V respectively. I added the EL34s. I started to adjust trimmer RV1 and blew valve V7 and R102. I replaced R102 [with a Royal Ohm(?) resistor], went over the soldering, removed all the valves and started again, LED12 still shone on standby.
In the process of checking the soldering I damaged the pcb, some of the Cu tracking lifted, around D11 and D13, I soldered across the lead [ie - to - and + to +] to make the connection.
What can I do next?
If a valve blows, this is usually caused by an interruption or wrong negative bias.
Check your complete assembly and make sure the negative bias is present and correct.
The amp has now been sent to Velleman Belgium.