Problem with tube rectifier PSU circuit

[beatnik]

Hello everybody

I am in the process of building a vari mu compressor with tube rectifier in the power supply

using an Hammond 370EX power transformer and a GZ34 rectifier tube

http://www.hammondmfg.com/pdf/EDB370EX.pdf

http://www.newsensor.com/pdf/sovtek/5ar4-sovtek.pdf

There is something obviously wrong. I am testing the power supply circuit without connecting the rest of the compressor circuit and rectifier tubes keep burning !!

The wiring has been triple checked and there is nothing wrong, I don't really know what's going on. The power transformer outputs around 630V AC  to the rectifier tube and the 5V for the filament is fine too. The first PSU capacitor is rated at 450V and that should be fine too, but there is absolutely no DC voltage on pin 8 of the rectifier tube, which after a few seconds from power up just emits some sparks and it dies out.

I have already burnt two rectifier tubes and I will definitely need some help before I do more damage

This is my first build with tube rectification, I didn't expect something could go wrong, the wiring is very simple. Maybe I didn't choose the appropriate rating power transformer ?

I hope someone can help me out so I can manage to get this working. Thanks in advance

 

[gridcurrent]

input capacitor too large ?

consider silicon diodes in series with the anodes.
despite the sceptics, the technique works.

 

[beatnik]

Input capacitor is 20uF 450V and the tube is rated at 60uF max, I am well below the limit

 

[beatnik]

damn this was a noob mistake !!

i had the rectifier tube filament center tap tied to ground and just assumed that it was the same as the 6.3V heaters

it's quite disappointing it costed me some rectifier tubes to learn this mistake but I am glad i sorted it out, now i can move on the next problem....

 

[Heikki]

Edit:
Never mind, I was slow at posting and you already found out what was wrong

 

[PRR]

1> The wiring has been triple checked and there is nothing wrong

Never never ever say that...

2> had the rectifier tube filament center tap tied to ground

Professionals make (almost) as many mistakes as beginners. The difference is that pros learn to find the inevitable mistakes quicker.