Buttercup
Well-known member
Well, I just etched my first circuit boards with a homemade UV box and they are a psu and an ELA M 251 board.
Both came out very well ( for my first go!! ) The psu uses the same
ht circuit as the original with a simple LM317 heater supply all on the same
board with a pcb mount 9v to 120v transformer with 240v to 15v feeding
it and the heater circuit.
I tried using an AC701 I had lying around and.......no hum at all but LOTS of hiss. Also, I tried using an EC1000 but I get the same hiss mixed in with the signal. Tried replacing the 8m resistor at the grid to no avail.
Output transformer is a 1:7 Stevens-Billington.
Any clues?
Coud it be the output cap - a really old Sprague red top 2.2uf?
Heeeeeeeelllllllppppppp!
Thanks
Both came out very well ( for my first go!! ) The psu uses the same
ht circuit as the original with a simple LM317 heater supply all on the same
board with a pcb mount 9v to 120v transformer with 240v to 15v feeding
it and the heater circuit.
I tried using an AC701 I had lying around and.......no hum at all but LOTS of hiss. Also, I tried using an EC1000 but I get the same hiss mixed in with the signal. Tried replacing the 8m resistor at the grid to no avail.
Output transformer is a 1:7 Stevens-Billington.
Any clues?
Coud it be the output cap - a really old Sprague red top 2.2uf?
Heeeeeeeelllllllppppppp!
Thanks