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Messages - olejason

#1
It works!  Hooking up an adapter to the breadboard seemed to do the final trick.  My battery was still reading around 8v but I guess the circuit was dropping it too far to power the IC's.  Someone mentioned that could be an issue a few posts back.

Thanks to everyone for all the help, setting up an audio probe will make all of this troubleshooting much easier in the future.
#2
Thanks!  The audio probe is helping.  I actually had a transistor with a wrong pinout in Q3.  Now that is sorted and I traced to IC1 and can still hear the clipped signal going through D1, D2, D3 up to C8 but then I lose it.  It also seems to be draining the battery rather quickly, maybe I should use an adapter for power for now?  It's late so I'll resume tomorrow. 

Bizarrely enough, the complete circuit passed signal for a moment after I changed the transistor.  I thought "Hey it's fixed" and went about hooking up the output to my amp.  Then it didn't work  ;D
#3
I received the replacement chips today but unfortunately I still don't get any audio when power is supplied to the PCB.  I was very careful to have both IC's seated in the sockets before connecting the battery for the first time.  Is there anything else you'd recommend trying?  I'm not real sure where to go from here.  I'm getting power throughout the circuit but I don't really know what kind of values I should be looking for.  If I turn the amp up quite a bit I can hear a little hiss coming through and it is affected by turning the pots.  Thanks all, I appreciate your help.

#4
Thank you Brian that is very kind of you, I went ahead and ordered a few earlier though since I needed some other parts as well.  They should be here this week and I'll update the thread... hopefully this will solve the mystery :)  Thanks again to everyone who has offered assistance.
#5
Oh wow, I definitely fried it then.  Unfortunately I don't have a spare but I'll order one now.  I don't recall how the IC was oriented when I first applied power but it very well could have been wrong at that point.  Would a bad IC explain all the weird oscillation noises and stuff when I jiggle it?
#6
Thanks for the words of encouragement everyone, I've managed to not get too frustrated with this one.  I tinker for awhile and then take a break.  I don't mind the troubleshooting as long as I feel like I'm making a bit of progress here and there  ;D

The TL074 IC does have a notch, sorry I should have noticed it was cropped out in those pictures.  I wasn't sure if the dot or notch took precedence so I tried the IC both ways just to be sure.  Below is a better picture of the IC & component side of the board and a picture of how I have everything breadboarded.  The red lead connected to ground is my input/output jacks.  None of the wires in the middle rows are connected to the PCB.  If I disconnect power and ground to the PCB I do get a guitar signal through the amp so the wiring appears to be okay.




#7
Thanks guys, here are some pictures.  I tilted the pots as best I could to get shots of the underside of the board.  The voltage does indeed drop when each IC is inserted.  Here are measurements:

Battery into breadboard, no load: 7.62v
PCB plugged in, no IC's:  7.42v
Only 4558 (8 pin) IC plugged in:  6.85v
Both IC's plugged in: 5.78v





#8
The battery seems to remain room temperature even after plugged in for 5+ minutes.  I don't feel anything getting hot on the board either.  I've made a bit of "progress" though.  At this point the voltage drops around 2v when the PCB is plugged in... so it stays around 6.5v-7v.  The big TL074 IC seems like it may be the problem.  If I fidget with it I can hear crackles and pops coming through the amp.  There are times that it will squeal or sound like its self oscillating if I slowly insert it into the socket.  I have voltage reading for all the legs of the IC except 11 which reads zero.  Also I don't think this is an issue but my socket is soldered in backwards (notch facing the wrong way) but I have the IC situated correctly in relation to the PCB.
#9
I went ahead and swapped the battery out just to be sure that wasn't the problem.  With a fresh battery it reads ~8.5v off the breadboard before I plug in the PCB.  Once plugged in it drops to around 1.5v and I don't get any sound at all.  I'm not sure what to try next other than resoldering everything which will be difficult with board mounted pots.  Everything looks okay but I know that can be deceiving. 

I don't know if this helps or is even relevant.  If I place an LED in the breadboard it will light up if either the PCB 9v or Ground lead is connected but if both are connected the LED no longer lights up.  This also applies to the PCB itself.  If I disconnect the PCB Ground from the breadboard, then place the LED in the positive pad on the board and then run a ground lead from the breadboard it will light up.  But if the PCB is also grounded it will not light up.

Thanks for your help guys
#10
Thanks for your time neandrewthal.  The resistance measurement between those two points is right at 15k.  I'm not real sure what I should be looking for with the measurement.  I checked a few other circuits I'm working on and they were significantly higher but also varied quite a bit.
#11
I'm sure this has been answered plenty of times but I'm not sure what to search for to find an answer.  Here is the issue:

1) 9v battery is plugged into breadboard, at this point I'll get a reading of 7.5-9v on the multimeter
2) As soon as my PCB is plugged into the breadboard, V+ going to positive and Ground going to negative, my reading will drop to 0-1v and no sound is produced.  Reading from the ground on the battery to the V+ pad on the board also shows the extremely low voltage.

Is this a grounding issue?  I've managed to fix it a couple of time by resoldering all my wires and cleaning everything up but I'd like to know what the actual problem could be.

One other question, I have a few PCB's with the standard +V, G, I, O layout at the bottom but they will also have pads for +9v and GND near the top of the PCB.  Are these just optional for hooking up the 9v adapter jack?  I should only be running power to one pad, right?

The current PCB I'm having issues with is the Grind Customs Helvete, if that helps.  Here is the layout:

#12
I have this mostly working after a lot of troubleshooting and learning.  I have two issues I'm still having trouble with, I can ask in the beginners section if that would be more appropriate.

1)  The heavy pot doesn't seem to do very much.  Is that normal?  I used a 5kB pot as spec'd in the document.  I do notice a difference when engaging the More switch but the pot doesn't seem to do much regardless of the switch status.

2)  When I install LED's I get significant volume drop.  After thinking about it, I may have the L1 & L2 wires breadboarded incorrectly.  Should they go to Ground or +9v?  I'll try this out when I get home.  I had them running to ground.  Switching the More switch on and off didn't disengage the LED so I definitely have something goofed here.

As an aside, flipping Q1 sounds pretty cool, I'm considering leaving it as is.
#13
Thanks!  Just waiting on switches to try it out.  Your pictures were a big help
#14
Hey Droogie do you happen to have pictures of the other side of your pcb?  I'm still pretty new to all this, it would be helpful if I could compare my build to make sure I have everything properly placed.  Thanks!
#15
Just wanted to confirm that this worked.  Thanks for the help!