NOOB Question Regarding Debugging First Stompbox

[petemoore]

  Q1 emitter voltage will measure 0.0v from ground when it's connected to ground.
  Use an online data sheet for the transistor to identify the E/B/C pins.
  EBC for 2n3906 [IIRC} legs pointing down, printed-flat-front facing you?
  That'd put the flat fronts facing the output end of the board?
  Been a while since I did a 2n3906 orientation check, check it.
  Every mark on the schematic must match every physical manifestation of the diagram [board components etc.], exactly, there's a way to test each one.
  Sometimes the overall view [just look over the wiring] does it', other times 'blinder-view' works better: concentrating on a particular active stage for instance or starting from Node:1, choose a node, count the #of connections shown on the schematic, measure that they're actually made on the board, note orientation of polarization [when shown], check and verify polarization of installed components.
  Measure the value of resistors joined to Node 1, measure anything else that can be measured from there...then move on to node:2 and so on.
 

[texstrat]

Keep at it. I've debugged stuff and found the problems to be (among other things):

I had the guitar cord in the output and the cord going to the amp coming from the input (hours of debugging)
A fried IC (I gave up on this, pulled the IC out for another project and discovered it was no good)
Transistor pinouts wrong (too many to count)
Fried transistors (a few)
A bad capacitor that took FOREVER to figure out
A bad guitar cable (yup!)

So keep at it. Many times it's something simple and/or silly! Hope this helps.
-Joe Hart

I will keep at it. I will check the capacitors next. I am definitely not a quitter, just need to step away for a little bit.

[texstrat]

  Q1 emitter voltage will measure 0.0v from ground when it's connected to ground.
  Use an online data sheet for the transistor to identify the E/B/C pins.
  EBC for 2n3906 [IIRC} legs pointing down, printed-flat-front facing you?
  That'd put the flat fronts facing the output end of the board?
  Been a while since I did a 2n3906 orientation check, check it.
  Every mark on the schematic must match every physical manifestation of the diagram [board components etc.], exactly, there's a way to test each one.
  Sometimes the overall view [just look over the wiring] does it', other times 'blinder-view' works better: concentrating on a particular active stage for instance or starting from Node:1, choose a node, count the #of connections shown on the schematic, measure that they're actually made on the board, note orientation of polarization [when shown], check and verify polarization of installed components.
  Measure the value of resistors joined to Node 1, measure anything else that can be measured from there...then move on to node:2 and so on.
 

Peter:

One thing I did notice different between the layout, schematic, and BOM is the 1M resistor (R12). It shows up on the BOM and schematic, yet it is missing from the layout and is not printed on the board. Could this be a problem? I believe it is on the output circuit. There is a 1M resistor, optional, on the input at R1. I did verify the transistor pins correctly. I have power to my Bias and Volume, but not to the Fuzz or Contour pots. Also I have power to the resistors, R11 and R2 on the transistor side, but when I check power, to the pot side, I get nothing. Resistor position reference is based on the layout sheet.

[Jhouse]

Are you sure that your solder joints aren't being grounded to your enclosure? It kind of looks like the joints around your pots are touching the metal of your enclosure in your pictures.

[texstrat]

The PCB is off the enclosure because of the wires. The joints around the pots, do you mean the pot terminals? I will check to see if by chance something is grounding out the Contour and Fuzz pots.

Back to the transistor values, what should my DMM be set to, VDC or Diode? Because the values I posted last night were with the DMM set to VDC. I was reading something earlier about testing transistors and it showed the DMM set to Diode.

[Cardboard Tube Samurai]

VDC is correct.

Don't stress about R1: that's just a pulldown resistor to reduce switch popping.

Any reason you have added D3?

*edit* Build instruction says:
"Note that including D3 will reduce the voltage to the circuit, the amount of
reduction based on the type of diode used. A 1N914 will reduce voltage to the
circuit by about one volt (this is not necessarily a bad thing for this circuit). C4
and D3 are not needed at all if you plan on using only battery power."
Have you tried it without this in circuit? Maybe just desolder and pop out one end.

I can't quite make it out from your pics but it looks like C1 might be back to front.

Also, have you definitely got it wired for Positive Tip on the DC jack? Looks to me from those pics that it might have a negative tip/center

[texstrat]

VDC is correct.

Don't stress about R1: that's just a pulldown resistor to reduce switch popping.

Any reason you have added D3?

*edit* Build instruction says:
"Note that including D3 will reduce the voltage to the circuit, the amount of
reduction based on the type of diode used. A 1N914 will reduce voltage to the
circuit by about one volt (this is not necessarily a bad thing for this circuit). C4
and D3 are not needed at all if you plan on using only battery power."
Have you tried it without this in circuit? Maybe just desolder and pop out one end.

I can't quite make it out from your pics but it looks like C1 might be back to front.

Also, have you definitely got it wired for Positive Tip on the DC jack? Looks to me from those pics that it might have a negative tip/center

I can pop out D3 and see what it does. This Fuzz Face is positive ground with PNP Si transistors.

[Cardboard Tube Samurai]

This Fuzz Face is positive ground with PNP Si transistors.

Yep, figured that bit out, hence why I'm suggesting that you check the polarity of the dc jack and maybe even the supply you're plugging into it.

[texstrat]

This Fuzz Face is positive ground with PNP Si transistors.

Yep, figured that bit out, hence why I'm suggesting that you check the polarity of the dc jack and maybe even the supply you're plugging into it.

I am confused, I thought I wired it like the layout shows, http://www.generalguitargadgets.com/pdf/ggg_ff5_lo_b69.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a

Do you see something I am missing?

Thanks.

[Jhouse]

EBC for 2n3906 [IIRC} legs pointing down, printed-flat-front facing you?
 That'd put the flat fronts facing the output end of the board?

In the schematic, it has Q1's collector going to R2 and B leg of Q2. It also has Q1's emitter going to the ground. 2n3906's are EBC with the flat side facing you, so that makes Q1's orientation correct. Q2 has its emitter going to R6 and R3, with its collector going towards R5 or the trimmer. That makes its orientation right also. I do believe that they are supposed to be facing each other.

What I don't get though is that the E on Q1 is supposed to be 0 because it is grounded.

Put your negative (black) probe on your ground and put your positive (red) probe on your V+ and post the value. Also, post your value for the leg of C2 (22uf) that goes directly to the ground. That should be 0.

[texstrat]

Jhouse, look at the picture in reply #13, that shows the proper orientation of the transistors.

I am working until Monday morning so I won't have an opportunity to post values until then.

I have another question that I asked earlier but no one replied,

"Something I did notice different between the layout, schematic, and BOM is the 1M resistor (R12). It shows up on the BOM and schematic, yet it is missing from the layout and is not printed on the board. Could this be a problem? I believe it is on the output circuit. There is a 1M resistor, optional, on the input at R1. I did verify the transistor pins correctly. I have power to my Bias and Volume, but not to the Fuzz or Contour pots. Also I have power to the resistors, R11 and R2 on the transistor side, but when I check power, to the pot side, I get nothing. Resistor position reference is based on the layout sheet."

Thanks.

[Jhouse]

Jhouse, look at the picture in reply #13, that shows the proper orientation of the transistors.

Awesome. I totally got those right.  

Something I did notice different between the layout, schematic, and BOM is the 1M resistor (R12). It shows up on the BOM and schematic, yet it is missing from the layout and is not printed on the board. Could this be a problem? I believe it is on the output circuit. There is a 1M resistor, optional, on the input at R1. I did verify the transistor pins correctly. I have power to my Bias and Volume, but not to the Fuzz or Contour pots. Also I have power to the resistors, R11 and R2 on the transistor side, but when I check power, to the pot side, I get nothing. Resistor position reference is based on the layout sheet.

No. It should be fine. Those are just there to prevent any "pop" you would get when turning on the circuit. R1 can be put in the slot below the input and connect to the slot directly below that. I think that R12 is also a pull down resistor . Maybe, I'm not quite sure  . If you want to add it though, attach a 1M resistor across the effect in (where the wire from lug 2 of the volume pot goes) and the ground (the middle one) on the 3PDT switch.

Again, make sure that your resistors (R2 and R11) are soldered in fully and well. That could be why you aren't getting any power to the other side.

Does your LED light up?

[texstrat]

The LED does and has been lighting up. I probably still have either dry or cold solder joints on the board that need to be fixed. What is the best way to reheat the joints without damaging the components, besides using a alligator clip? How long is too long or not long enough? Is there a rule of thumb? Keep in mind I am using a hand-held soldering iron and I am not sure what the temperature rating is on it right now.

[Jhouse]

I'm confused now. If R11 wasn't getting any voltage, the LED would not light up. Also, the side of R2 that faces towards the pot is directly connected to V+ so it should get the full voltage if it is soldered in.

You can put pliers on to hold the part and not let go until the solder cools. It should only take about a second, long enough for the solder to get shiny.

[texstrat]

I will get some things done Monday and get some more data posted.

[texstrat]

In the schematic, it has Q1's collector going to R2 and B leg of Q2. It also has Q1's emitter going to the ground. 2n3906's are EBC with the flat side facing you, so that makes Q1's orientation correct. Q2 has its emitter going to R6 and R3, with its collector going towards R5 or the trimmer. That makes its orientation right also. I do believe that they are supposed to be facing each other.

What I don't get though is that the E on Q1 is supposed to be 0 because it is grounded.

Put your negative (black) probe on your ground and put your positive (red) probe on your V+ and post the value. Also, post your value for the leg of C2 (22uf) that goes directly to the ground. That should be 0.

The battery tested at 9.29 V, V+ was 9.20V and C2 postive leg was 9.20V.

[Jhouse]

C2's positive leg was the same as V+? If it's going to ground, it should be 0 I do believe. Check your wiring and make sure it is EXACTLY like the wiring layout tells you to wire it.

[Govmnt_Lacky]

The battery tested at 9.29 V, V+ was 9.20V and C2 postive leg was 9.20V.

C2s POSITIVE leg should be V+! If it is a PNP circuit and you have the electro cap inserted correctly.... then it should read as V+ at the positive leg.

[Jhouse]

Whoops. For some reason, I totally missed that it was a positive ground circuit. You would think I would notice that when I knew the transistors were PNP.  Sorry about that.

[texstrat]

So far I have isolated the problem to the contour pot. I have voltages going to all pots except the contour. Where I am having a problem is with resistors R11 and R2, I get 7.8 volts on one end and ) volts on the other for each. I have desoldered the joints and resoldered, but no change. I ohmed the resistors and they are correct 1k and 33K.

So any ideas what I can check or do and what could be the issue with the contour pot?

I can noted the voltages to each connection point on the individual pots if that would help.

Thanks.