aikido 12vac help needed

[shine20]

Hi I've finished building the aikido 12vac pre amp from John broskie and I've been having a few issues getting it to run properly. Sometimes it work flawlessly but every so often when I turn it on resistor 2 fries. I've checked all the components and there all the correct values and it the right position. also When its working sometimes one of the channels doesn't work or its very quite. I tried rotating the tubes around but it just fries a different resistor usually resistor 11. I'm using 1/5 watt metal film resistors. Any help would be great. Thanks

 

[Koifarm]

Schematic would help.
With tubes do you use?
And have you considered 1watt resistor for R2 and R11.
If problem change from R2 to R11 after tube change it is a bad tube.

 

[nigelwright7557]

I use 0.6 watt resistors as standard unless I need a higher power.

 

[ClefChef]

I think the resistors are specked 1W for Rk - there's quite a bit of current that travels through them. Same for PS filtering resistors - should be at least 2W. 1/5 watt resistors are way too low.

 

[shine20]

Hi im using jj electronic e88cc tubes. I've included the schematics and recommended part values below. thanks for your help. Allister