HerbertR said:All diodes and Capacitors are correctly placed with their poles. What could.be the problem....?
Sounds like you have a short or a bad tube/part somewhere. Did you try powering up the circuit without the tubes installed? I would first replace R3 and power up the PSU without the main PCB connected, check voltages and make sure the PSU is ok. Keep in mind, your voltage readings might be a little higher than expected without a load connected to the PSU. If all is well, I would connect the main PCB without the tubes installed and check voltages again (without tubes installed, the voltage readings might be high). I would then install 1 tube at a time (obviously install tubes when power is off) and see if you could locate the problem. Or, you mentioned the EL90 is getting hot, perhaps start there and try removing the EL90 and see if the problem persists. Could be a faulty tube? This is assuming you scrutinized your soldering for shorts/bridges, etc.
In short, I would fix the PSU and then systematically work your way through the circuit to narrow down where the problem is.