express issues

[bigmik]

hey guys finally fired my express build up a few days ago but it has issues,the notes have a fluttering sound behind them it is more notcable
when playing higher upon the neck like if you play at the 12 th fret b string and g string together it really get's it going it's almost like a tremolo effect in the background. also the volume and the treble knob in the last 1/16 inch of their swing make the amp squeal almost as if they have grounded out .I have double cheaked the the layout for errors ,re soldered all the conections, moved all wires from the bottom of the preamp to the top to verify integerity , tried different tubes pre and power, chopsticked all of the wires, disconected and reconected the NFB,removed the bias pot and replaced it with a resistor because i wasn't shure if I had conected correctly ,moved power supply board forward and then back to the origional position .none of this had any affect on the problem.I really dont know what to try next without ordering and swapping out the caps and other componets.anybody got any ideas or see a problem with my layout?


thanks
mik

[bigmik]

more pics

[UR12]

Is it me or are you missing a connection on your PI tube. Pin 3 looks like it isn't connected to anything. It should be jumpered to pin 8

[Allynmey]

Dana, the picture I see has pin 3 of the PI unsoldered. Maybe you took this picture before you finished?

[bigmik]

wow you guys are the best ,very sharp eyes, I went over that amp way too many times to have missed that, but that fixed the problem no more fluttering and the volume and tone dont squeel anymore i also changed the 10k tail resistor 22k that smoothed out the amp a lot, right now the amp sounds really good and am very happy with the sound it is very quiet no hiss or hum even when dimed ,full of harmonics and cleans up better than any amp that I have ever played with the volume knob .

THANK YOU VERY MUCH!!!!!

[UR12]

Your welcome! Everyone misses a wire now and then no matter how many times you look at it . Glad to hear you got it going !!

[drhulsey]

... are you missing a connection on your PI tube...

The Halls Have Eyes Wasn't that the name of a movie