Can I get a little help with my Ampeg Scrambler?

[peps1]

Just hooked up my Ampeg Scrambler clone, and i seem to be getting something strange. 

Switch OFF, Clean tone (yay!)
Switch ON, Clean tone, with Balance pot working as volume control.

Here is how iv got her hooked up......Iv double cheeked the transistors are in the right way (as it ECBE on the left two then BECE on the right).....but was wondering if i could have wired the pot up back to front, as there is no lug numbering on the tonepad layout?

as always any help would be much apprechiated as Im new to this......but LOVING IT!

[yyz_2112]

Doesn't look like your input jack is grounded. May not be the problem though.

[peps1]

Doesn't look like your input jack is grounded. May not be the problem though.

Very true, should have said that iv been using a crocodile clip cable grounding input to out......(forgot to include it in the photo)

[yyz_2112]

Your switch wiring looks a little suspect also. Why did you jumper the lug at the top left to the bottom middle? Is that a ground?

[Vince_b]

I'm pretty sure that the problem is with the pot you should have wired them from the other side.

[yyz_2112]

I'm pretty sure that the problem is with the pot you should have wired them from the other side.

At worst the pots will work in reverse, I don't think that's the issue.

[peps1]

Your switch wiring looks a little suspect also. Why did you jumper the lug at the top left to the bottom middle? Is that a ground?

Yes Pink is ground.
Blue = input
yellow= out

been using this layout from gaussmarkov: diy fx

[The French connection]

check your trannys pinout again and look for solder joint or shorts...if nothing then audioprobe and follow debugging thread. The switching is correct: the circuit input is grounded when bypassed.

Dan

[yyz_2112]

Ok, never used that wiring method before, so it looked odd to me. Carry on.

[peps1]

check your trannys pinout again and look for solder joint or shorts...if nothing then audioprobe and follow debugging thread. The switching is correct: the circuit input is grounded when bypassed.

Dan

Thanks Dan, checked trannys pinout many times now, and solder joints seem fine......even switch the pots round

I don't have an audio-probe, but did rebuild the whole circuit from scratch....taking uba special care not to get a short, same results 

[Cardboard Tube Samurai]

That looks to me like you've got the output going to the sleeve and not the tip.

Actually, just looked at both pictures and you've got the ground and outputs swapped on the output jack in both. Double check the wiring on the input too while you're at it. Use a multimeter to make sure you're wiring to the right lug

[peps1]

That looks to me like you've got the output going to the sleeve and not the tip.

Actually, just looked at both pictures and you've got the ground and outputs swapped on the output jack in both. Double check the wiring on the input too while you're at it. Use a multimeter to make sure you're wiring to the right lug

Thanks for taking a look.

Iv got the white wires going to tip lug on both input and output jacks, and both the GND (pink) going to sleeve......is that wrong? 

[Solidhex]

The input jack's sleeve lug shouldn't be connected to the "input" on the footswitch. That wire should be connected to the "tip" lug (left side not right). You'll want to connect the "ring" lug of the input jack to ground also (middle lug). I also noticed that your knobs were wired backwards in the first pic. You corrected that in your rebuild.

--Brad

[peps1]

Thanks Brad, But is that not how iv got it........you may have to go easy on me as im a little slow

[petemoore]

  "Beep Mode":
  DMM [beeps when leads touch]...verify that all points marked ground connect to all the others, including usually the sleeves of the jacks.
  Make sure ground goes nowhere else, particularly the tips of the jacks, turn your pots away from ground setting to prevent 'anomolous' ground readings from a wiper.
  Easier when the black lead is clipped to say a sleeve or other Gnd. point.
  Clip or touch the black lead to a node, follow that node connections to the farthest point [say like a transistor lead, so that you're testing for cold solder joints and connections as you measure resistances].
  Start with the black lead clipped to the input jack tip, should go where shown on the bypass switch, then through the switch one way [for bypass] and the other way [effect mode], to reach the circuit input node. Similar method for output..

[peps1]

Hey petemoore, My DMM is a cheap one without a Beep mode   

[tcobretti]

I would ditch that switch wiring layout in the future - it is unnecessarily complicated.  I can't tell from the photo, but it looks me like the ground isn't going to the sleeve on the stereo jack, but to the 2nd tip.

The next step is to audio probe the circuit to find out where the signal stops.  I'm willing to bet it's a transistor or solder flow problem.  That's what it is 99% of the time for most problematic builds.

[peps1]

well the audio prob dost even want to pick up a signal, so im incline that it thee jacks that are hooked up wrong.......going to swap the PCB with one i know is working, and see how that goes 

[petemoore]

  I'd get the audio probe working first, then the signal routing.
  Then debug the PCB as necessary, is the PCB verified ?

[Solidhex]

Thanks Brad, But is that not how iv got it........you may have to go easy on me as im a little slow

Oh, sorry man. You're right. Those jacks are different than the switchcraft ones I always use. Weird.

--Brad