Fender Blues deluxe distorted sound

[blindboybenton]

Hi all.

Im losing my hair on this one

Was told it had distorted . I bugged a new set of tubes in for test, still distorted. and low ( ish on output, Tried another speaker
when using the signal gen and scope i noticed at V3 Pin 1 - 6 the signal was all over the place
up and til about no 3 on vol clean channel it would be good after 3 it would start to get like this
BluesDeluxe_Reissue_2004_schematic_Rev-A.pdf

Pin 6 V2 signal good i think

V1 pin 1 258v
V1 pin 3 2.0v
V1 Pin 6 245v
V1 pin 8 2.0v

V2 pin 1 245v
V2 pin3 1.95v

V3 pin 1 256v
V3 pin 3 36v
V3 Pin 6 256v
V3 Pin 8 24v

I think the fault is somewhere between V1 output and V2
Ive tried other tubes and still the same

can anyone help.... Be nice as i do this for the fun really

Bassman 1965

[Enzo]

On all the amps of that series, the Blues and Hot Rods, I automatically check the solder, and redo it, on the power tube sockets, and check the 9-pin ones. Also I check the phase inverter plates, open plate resistrs happen too often. And I verify the speakers plugged into the main jack, not the extension jack.

As to any distortion, use a scope or signal tracer to follow a signal stage by stage. Sine wave in, is signal still clean at V1-1, and at V1-6? Does it matter which channel is selected? Clean at V2-1? You have a power amp in jack, so plug signal into that, does that come out the speaker OK? Note that none of the solid state stuff is involved unless you use the FX loop, except for the mute transistor. JFET Q1 is always on my suspect list, too many of those in various brands of amps come up leaky. Nearby pair of zeners clamp signal at 16v, I rarely see those fail, but won't hurt to check.

[blindboybenton]

Thanks enzo

Im running at present without output tubes. with tubes in and speaker attached or test speaker sound is distorted.
Checked all the parts you say, and re-soldered the tube bases. two zeners are fine as are all the other diodes.
Plate resistors are ok. i removed J1 and one leg snapped off while soldering it back so i fitted J112 which seems to be the same thing
Its the same on both channels worse on drive channel
Power amp in jack signal injected all good, double checked with audio cd and all good
Signal at V1 pin 1. good and at Pin 6 its good >> on X10 on clean with vol on max

V2 Pin 1 clean channel vol about half way

[g1]

Not sure what kind of signal level you are applying at the input jack.
The schematic shows test points for both AC and DC levels. The DC are in boxes, the AC in circles.
In the notes at the bottom of the schematic, it lists the input level to use, and where to set the controls.
Check the AC levels at TP2, 5, & 8 under the listed conditions.
You have verified that the power amp section is ok, so you only need to look at areas before the preamp out jack.