I have a ZSP 1 that I completed and tested last night and it worked great! Today when I got off work, I hooked it up again and I am getting a HUM through both channels. I have pulled the tubes from each channel and shorted the input but the hum is still there. I have also visually inspected all the solder joints and can not find any loose connection.


Can anyone give me any pointers as to what to look for next?

Thanks

Robert

Glad you could help.  [smiley=laugh.gif]

Rap wrote on 03/26/07 at 23:57:23:


Well after using the alternate wiring schematic for "noisy" tubes, I still have too much hum for my tastes. Would it help to put a diode in each leg of the filament winding? What value capacitor would be needed to smooth out the ripple? Or is this all totally off base?


Thanks

Robert

Rap wrote on 04/18/07 at 12:07:38:



The cause was much simplerthan that. In my haste to gear the preamp in operation, I used a three prong power cord but, had to put a two prong adapter on it as the outlet in the house was not three prong. I kept plugging it in the same way each time and getting hum.  ::) I thought I had a ground loop and I flipped the plug on the amplifier and I still had hum. It took a few days to try that with the preamp plug. Once I did that the hum went away.

Now I have to get under the house and run a ground wire for that outlet.  >:(

I know this is a little unorthodox but, take the two prong outlet out of the wall, get a 3 prong outlet, jump a lead from the neutral (white) to the ground terminal and hook the hot(black) as normal. This will get ya going until you can install the correct wiring. Remember the white (neutral)wire goes on the silver screw and the black (hot) wire goes to the copper screw and ground is the green screw (but you already knew that - right?  ). I've had to do this in the last 3 places i've rented here in wichita. ALOT of the houses and duplexes out here still have 2 wire house wiring. Also, get one of those outlet checkers from lowes or home depot or similar store. always best to make sure ^^