help Etude 124BA keep blowing fuse.

[jj2]

just finished building Etude 124BA , but it keep blowing fuse.
the transformer is hammond 550CT 150ma going into a db2504p bridge rectifier then to JJ 50uf >1K resistor >50uf.
I have try 500ma, 1A and 3.5A , they all blow.
how big a fuse do I need?
Thanks for any help .

[arnoldc]

i'm using 1A on my 12B4.

there must be something terribly wrong with the PSU for it to blow a fuse. have you triple checked everything? cold solder? short? bad part?

[kevinkr]

I'm not familiar with the specific project, but here are some basic troubleshooting guidelines.

Be careful and make sure anything you disconnect is properly insulated and can't short to each other, you or the chassis.

I would start by trying to isolate the cause of the fuse blowing.
To begin with try disconnecting the bridge rectifier from the transformer and see if the fuse still blows, if it does disconnect the filament lines and try again - if it still blows it is likely that your transformer is bad.

If on the other hand the fuse does not blow, check the way you wired the bridge rectifier and make sure that it does not have any shorted diodes. Replacing it is recommended if it was wired incorrectly. Also check to make sure that your filament wiring is correct that there are no shorts. Check values of any other components used in your filament supply.

Should you get past this point recheck all of your wiring very carefully.

[jj2]

nt

[kevinkr]

Its amazing how little things can cause so much grief..