Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Douqep on May 03, 2019, 12:57:10 pm
-
Hi all. Thanks for accepting me. I just finished a 5F1 build and did the steps for firing it up: 1. plug in no tubes/speaker, plug in, pilot light comes on; 2. add rectifier tube, plug in, light comes on, rectifier burns; 3. add pre-amp tube, plug in, light, rectifier and pre-amp both burn; 4. add power tube, plug in speaker, everything works, white noise out of speaker; 5. plug guitar in, plug in, light blinks and then it's dead. It's totally dead and nothing makes it come back. I've been over the wiring. Did I blow the OT somehow? What would cause it to be ok until I plug in the guitar? Thanks for any responses.
-
Oh, and the fuse is not blown, which troubles me..
-
Do you have a VOM? Check to see how far your power is going from your cord connection. Sounds like a simple loose wire/solder joint issue. I am assuming no filaments in the tubes are lit either? You wouldnt happen to have this plugged into a GFCI protected outlet that may have tripped somewhere else in the house? Check the outlet first. Sometimes it’s the silliest things that send you on a wild goose chase in the wrong direction.
Jim
-
Thanks. Outlet is ok. I'll go over the wiring again. I don't like the turrets I used for the circuit board--connections didn't seem real secure to me so that could be it.
-
Connections as in turrets to board? Or wires to turrets? A loose turret on a board isnt ideal but as long as it’s in no danger of falling out you should be ok. A bad solder joint is a problem.
Jim
-
Remove all tubes but the rectifier. Record all the voltages. What s the heaters voltage ?
Plug in one tube at the time starting by preamp and record the voltages once again with each new tube added.
-
You said "light blinks and then it's dead'. You mean, the amp does not turn on at all now? If so, that would say blown fuse. If it is indeed blown by you plugging in your guitar, then take a close look at your input jack wiring. I can't imagine how, but maybe you somehow sent the B+ voltage straight to ground. Hair strand of solder on the socket pins, or if you used shielded cable from jack to first grid, maybe that shield (ground) touched high voltage.
-
Oh, and the fuse is not blown, which troubles me..
I think it is something much simpler. Unless this fuse inspection was a visual one. Hopefully he checked with meter.
Jim
-
If outlet and cord is good he needs to find where the voltage stops.
Jim
-
Oh, and the fuse is not blown, which troubles me..
I think it is something much simpler. Unless this fuse inspection was a visual one. Hopefully he checked with meter.
Jim
Duh, totally missed that post.