[TUBE] amp troubles, champ-like clone

[jimmy]

hi everyone

working on my latest tube amp, and its all wired up, but ive hit a snag. on first fire up, it works, but its really quiet, and you can only hear anything coming from the speakers when you poke the signal lug on the input jack.

for once everythings wired all neatlike too    ive got no idea whats going wrong so i hope one of you guys can set me straight.

sorry for bothering you with amp problems again.

http://photobucket.com/albums/v323/jm121088/schems/?action=view¤t=champmodschem.gif

cheers
Jim

[puretube]

disconnect the FB trimpot from the output winding (for a 1st test)  :?:

[puretube]

got 6V3 at the filament pins?  (not "almost 5V", or so !)

[jimmy]

thanks for the quick reply!

im not using a rectifier tube, im going SS for this time.  ill go disconnect the feedback pot and get back to you.

thanks

[Johan]

..is the other side of the o.t's secondary winding grouned? ..if not, the reference might be way off...
...if you cant see the ground, how do you know how high you're flying?...

Johan

[jimmy]

:shock: no. no it isnt.

tried disconnecting the feedback pot, no luck. ill ground that right away an get back to you in the next few mins.

cheers
Jim

[puretube]

Johan: I failed to see that, but there was s.th. wrong, there :wink:

Jimmy: if it works now, but howls when you re-connect the feedback pot,
reverse the 2 output connections...

[jimmy]

not alot of luck there. the star ground point looks a little unstable now, so in the morning il resolder it and see if that makes a difference. thanks for the help, and ill report back tomorrow.

thanks alot!
Jim

[GreenEye]

also try diyaudio.com

[jimmy]

SORTED. resoldered up the star ground, and rewired the preamp tube just in case, and all was fine.

i DID have the tortured soul/possessed screaming when i reconnected the feedback pot, but thats fixed now also.

it sounds preeeeeeetty good    im very pleased.

thanks alot!!!
Jim

[jimmy]

hi again,

i recently installed a FAT switch in the first gain stage, (22uF) and now when the FAT switch is on, and the SECOND volume knob is turned down, even just a little, it squeals. it doesnt do this with the first volume knob, or when the fat swith is off. any ideas?

thanks
Jim