That's soo cool, the distortion is gone, completely!  :dbtu:

A bridged amplifier inside the TDA-Chip and a missing  HF-cut.

I am out for work for a week now, but i am thinking to do a modifikation, that i have two inputs like my Vox Escort.

I would like to have in the front one input for my guitar and in the back a second input in paralel for FX or Playback.
So i would need a High Gain and a Low Gain Input.
I will look inside my Vox but if you have ideas or suggestens please let me know.

thanks so far. :tu:

What is also interesting is the schematic of the TDA7240A in the datasheet. (see below)

On the Output-Side are two C's and two R's (2,2 Ohm & 0,22µF).
I am asking myself, if that could be better by changing that in the Pignose...
It would be more symmetrically.

Any suggestens?

The C14 in Pignose schematic goes directly to GND.
There could be a R in series with that.

Sure some more pics.   8|

If you are interested in more let me know what you would like to see.
Maybe i will change the 1µF to .47µF if that is better?

I played now for an hour and there is just a little, little subtile distortion left.
I recognize that when playing more the Bass and darker Tones.
Maybe the batterys are a bit week.

By the way much better than before...

The Blue One is the New One!  :tu:

Ready to Rock...

 :duh

That was the Prob...
A missing C 15 was it.
I put in a 1µF instead of .47µF that solved the Problem no more distortion.  cool!
Thank you all, haha.   :dbtu:

QuoteBut still clean on headphones?

yes

QuoteWas the AC-30 speaker test with the headphone switch contact bridged by wire?

yes

QuoteTo test the Pignose speaker, disconnect it from the Pignose amp and drive it (gently) from the AC-30 output - fault or no fault?

no fault

I found out...
When headphone is plugged in and contact bridged by wire to the ac-30 speakers, signal is clean at the cabinet as it should be and clean on the headphone.
I will check that with the speaker inside the nose.
Yes with headphone and Pignose Speaker no faults.
hm...

Contactspray didn't solve the prob.

The C and R at the Phonejack is not the problem, cause they have just the function to divide the output-signal. 1:10

When i am right, the C 14 & R 10 is a simple LowPass. I will lift them up to see what happens.
Oh much more distortion.

Maybe the C15 0,47µF 50V is the prob?
Oh what is that???
There is no C15 in the board. There is no place for it...

hello friends,

i checked now with my ac-30 cabinet and it is still the same problem.
When the sound is getting quieter the more distortion came.
hm... :loco

Here are my measurements on the TDA 7240 in DC
Ground to

Pin 3=5,62 V      (Input)
Pin 5=5,67 V      (Output)
Pin 6=12,08 V     (Supply Voltage)
Pin 7=5,74 V      (Output)

next i will test with another speaker and let you know.

Too bad that i can not upload a video (.mov) with the mistake...

Many, many thanks for the support!
Ich will check the phone-connector with soldering a wire over the switch.
And let you know.

Thank you so far.
Good idea with Elektor and farnell.
I live in .de

best

I am trying to repair mine.
There where some faults i could fix, but not yet all.

For example, the Switch of the Squeal Pot was broken, thats the reason i build in a new one.
What i didn't know before ordering was, that it should have been an opener switch.
I bought a Closer...  :-(
For the moment that is ok, cause i do not need the distortion.
If someone here has an idea where to get one here in europe let me know.
I can buy one from Pignose directly, but the shippingcosts will be much higher than the pot.

Then another fault was the Input-Connector on the backside.
I build in a normal Connector, cause i do not need the switching.

Then the Tone-Pot had a loos connection. I could fix that by cleaning it.

So now the last thing what i think is broken is the TDA7240.
With headphones the sound is quiet fine, but when i hear over the speaker, it is strange.
If the sound is loud it is free from distortion. If than the guitartone gets quieter the distortion starts.
So normally i would expect that it is the way round but it isn't.
The loudspeaker is ok, i checked it.

So after changing the TDA (maybe this week), i will try new caps.
Hopefully some day it will sound fine again.
I never heard him playing right...

I know this is an old thread, but I came here by a search-engine looking for the schematics.
Just want to post, if someone else is searching...

Best