Author Topic: Poindexter problem  (Read 3171 times)

youngstownguitar

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Poindexter problem
« on: March 12, 2012, 03:16:35 PM »
Hi

Im having some trouble with my poindexter build and I could really use some help.

When I hook everything up there is no bypassed signal at all, totally muted.  When I engage the pedal the LED lights up and there is some static that changes when I adjust the knobs on the pedal but there are no notes or signal from the guitar.  This is the same wether I use my one spot adaptor or a tested 9 volt battery.


I built the pedal exactly to spec, no changes at all.  I did remember to reverse C11 as it is noted in the PDF.
Here is the poindexter PDF:
http://madbeanpedals.com/projects/Poindexter/docs/Poindexter.pdf


There are 5 transistors, all 2n3904.  Here are the voltage readings I got on from them:
Q1:  E:  0
        B:  1.2
        C:  5.2

Q2:  E: 2.8
        B: 0.6
        C: 4.4

Q3:  E:  0.8
        B: 0.8
        C: 3.2

Q4:  E:  0.8
        B: 0.8
        C: 3.2

Q5:  E: 0
        B: 0.4
        C: 5.8

And reading from the diodes:
D1 A- 0
      K- 0

D2 A- 0
      K- 0

D3 A- 0
      K- 9




Here are some pics:  I really tried to light them as best as I could.










mgwhit

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Re: Poindexter problem
« Reply #1 on: March 12, 2012, 03:34:39 PM »
Your post should be held up as a model for debugging request posts!  Awesome pics and voltages up front.  Love it!  Unfortunately, I don't have time to look at them right now -- wrapping up work and band practice starts in 30m.

I will say, though, that if you are getting neither bypass nor effected signal in a true-bypass 3PDT switch setup like this, then you have a definite wiring problem in your switch or your jacks.  The jack wiring looks good from what I can see, so I'd check to make sure you don't have a cold joint, a short to ground or (ugh) a bad 3PDT switch.  This is easy to do with the continuity test on a DMM as long as you know which lugs are supposed to have continuity in each switch position.  Good luck!

madbean

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Re: Poindexter problem
« Reply #2 on: March 12, 2012, 03:43:56 PM »
What you have on the switch looks right, but check to make sure you have correctly wired the input and output to the tips of the jacks, and that your ground is consistent from the PCB to the switch, to one of the jack and to the DC jack.
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youngstownguitar

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Re: Poindexter problem
« Reply #3 on: March 12, 2012, 03:46:13 PM »
Thanks for the input.  I thought it may be a wiring problem so I checked a rechecked all my connections and I believe that they are all good.  I cant find a short anywhere either.

 
This is easy to do with the continuity test on a DMM as long as you know which lugs are supposed to have continuity in each switch position.  

Im not sure how to do this- anyone have a link?  Do you guys think it would help me?


And I did check all my jacks about 5 times now lol.  I believe they are all right

youngstownguitar

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Re: Poindexter problem
« Reply #4 on: March 12, 2012, 07:10:20 PM »
Thanks for the tip madbean.  I checked everything over and over again and I cant find a problem.

Would it help if I reheated all my solder joints on the input, output, DC, and switch?  They all look OK to me buit Im thinking maybe one of them is cold. 

Is that a good next step?  What would you more intelligent people do next?

mgwhit

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Re: Poindexter problem
« Reply #5 on: March 12, 2012, 07:14:21 PM »
It looks like you used the MadBean Wiring Layout, so when you arrange you pedal vertically you should imagine the lugs on your 3PDT switch numbered like so:

  A  B  C
1 -  -  -
2 -  -  -
3 -  -  -


When the effect is bypassed, there should be continuity between 2A & 3A, 2B & 3B and 2C & 3C.  There should not be continuity between 1A & 2A, 1B & 2B or 1C & 2C.

When the effect is engaged, there should be continuity between 1A & 2A, 1B & 2B and 1C & 2C.  There should not be continuity between 2B & 3B or 2C & 3C.

Testing continuity on those lugs for both switch positions will confirm that the switch is (internally) functional, but you could still have cold solder joints on those lugs.  Test continuity between lugs 1B & 3C, between the Tip lug on your Input jack and 1B, and between the Tip lug on your Output jack and 2C.  These should have continuity regardless of the switch setting.

The grounding on the switch must be working because the LED is lighting when the effect is engaged, so I didn't bother with asking you to test those lugs, although we may have to come back to them later.

I also just noticed how perilously close the Tip lug on your Input jack is to the case wall.  Please make sure it's not shorting against the case.  Good luck!
« Last Edit: March 12, 2012, 07:19:53 PM by mgwhit »

mgwhit

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Re: Poindexter problem
« Reply #6 on: March 12, 2012, 07:19:12 PM »
Would it help if I reheated all my solder joints on the input, output, DC, and switch?  They all look OK to me buit Im thinking maybe one of them is cold.

Yep.  The 3PDT is the only place I have ever had a cold solder joint on a pedal build.  I'd still test them first (as above) -- you might find the cold joint that way -- but even if you don't find anything, go ahead and reflow them.  The problem has to be somewhere in the wiring of the jacks and the switch.

youngstownguitar

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Re: Poindexter problem
« Reply #7 on: March 13, 2012, 02:57:30 PM »
Thanks for all the input mgwhit.

I reflowed all the joints on the 3PDT, input, output, and DC jacks.  I made sure the tip lug was not shorting out on the case wall.  Same problem tho- no signal bypassed or not.

Then I broke out my continuity tester and tested the things you mentioned.  I should not that while the lugs on the 3PDT are not perfectly soldered they are certainly not grounding or touching anything they should not be.

Bypassed:
"When the effect is bypassed, there should be continuity between 2A & 3A, 2B & 3B and 2C & 3C.  There should not be continuity between 1A & 2A, 1B & 2B or 1C & 2C."
PROBLEM- there is continuity between 1B and 2B.  I also noticed that while there is not continuity between 1A and 2A, when I connect them the LED lights up.


Engaged:
"When the effect is engaged, there should be continuity between 1A & 2A, 1B & 2B and 1C & 2C.  There should not be continuity between 2B & 3B or 2C & 3C."
PROBLEM - I am seeing continuity between 2A and 3A, as well as 2B and 3B.

I have tested all these things several times to be sure and I am positive these are correct readings.  Any idea what they mean?

madbean

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Re: Poindexter problem
« Reply #8 on: March 13, 2012, 03:23:58 PM »
I think your switch is bad, based on the continuity issue. If you've remelted the joints and they look good, it's the only thing left.

The only way to test definitely is to remove all the wires from the switch and use your cont. checker again to see if you have these connections.

Toggle 1
1a, 2a
1b, 2b
1c, 2c

Toggle2
and
2a, 3a
2b, 3b
2c, 3c
« Last Edit: March 13, 2012, 03:30:57 PM by madbean »
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youngstownguitar

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Re: Poindexter problem
« Reply #9 on: March 13, 2012, 03:40:24 PM »
Interesting.  On one had it sucks I need to order a new 3DPT but on the other hand I guess it means I didnt totally screw it up.

Is it rare to get a bad 3DPT like that?

btw, thanks for all the help guys- I never would have figured that out.  I am going to order a new switch and try that out- I will post the results.

mgwhit

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Re: Poindexter problem
« Reply #10 on: March 13, 2012, 09:14:27 PM »
Is it rare to get a bad 3DPT like that?

I've never gotten a bad one, but I've only got about 10 builds under my belt, and only a few of those have gotten a real workout.  Others have mentioned throughout the forum, however, that 3PDT switches are one of the parts with the highest failure rate.  I've taken to doing those continuity tests on my 3PDTs whenever I get a new parts order in.

youngstownguitar

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Re: Poindexter problem
« Reply #11 on: March 20, 2012, 12:53:01 AM »
Ok I got a new 3DPT and I tested it out before I installed it.  I took extra care when soldering and Im sure no joints are cold and all connections are correct.

 Same exact problem!  It must not have been the 3DPT I guess.  What should I try next guys?

I reviewed the board and all joints look really clean and correct.  The pots are hooked up right and so are the in and out jacks.  The only thing that doesn't look perfect is the boss adaptor.  It doesn't look bad- just could be a bit cleaner- could that be causing this problem?  I am thinking of just getting a new DC jack and in/out jacks and just redoing the whole thing.

Just to reiterate, there is no signal whether the pedal is bypassed or engaged.  When engaged there is some static when you turn the pedal volume up.  The LED works properly.

So what would YOU try next?

mgwhit

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Re: Poindexter problem
« Reply #12 on: March 20, 2012, 06:09:25 AM »
Sorry the new 3PDT didn't fix the problem.  I think you need to try debugging the least complicated problem scenario: no sound in bypass mode.  You can do this with your DMM continuity test.  Plug cords into both the input and output jacks, disconnect them from your amp and guitar, and set the pedal to bypass mode.  If bypass were functional, you would have continuity from plug tip to plug tip and neither tip would have continuity to ground.  So what you need to do is test every point along the bypass signal path (a.) for continuity to the tip of the input plug, and (b.) no continuity to ground.

Test points include: the tip lug on your input jack, 3PDT lug 1B, 3PDT lug 3C, 3PDT lug 2C, output jack tip lug, output plug tip.  If any of these points does not have continuity back to your input plug tip OR does have continuity to ground, you've found your problem.  Good luck!
« Last Edit: March 20, 2012, 06:11:20 AM by mgwhit »

madbean

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Re: Poindexter problem
« Reply #13 on: March 20, 2012, 07:28:20 AM »
To further expand on mgwhit's post: remove the circuit completely from the enclosure with the pots. Get the bypass working in the box with the jacks and switch and the LED. Test the circuit outside the box to make sure the actual build is also working. Put it back together. If it still does not work you know it's got to be the wiring or some piece of hardware that's causing the issue.
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jimmybjj

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Re: Poindexter problem
« Reply #14 on: March 20, 2012, 07:44:47 AM »
To further expand on mgwhit's post: remove the circuit completely from the enclosure with the pots. Get the bypass working in the box with the jacks and switch and the LED. Test the circuit outside the box to make sure the actual build is also working. Put it back together. If it still does not work you know it's got to be the wiring or some piece of hardware that's causing the issue.

+1 I treat all of my builds as 2 circuits. The first being the pcb. And the second being the completely wired box, making sure the led, bypass and pcb signals (using a jumper for pcb leads) all funtion. I almost never have to debug once I have boxed the effect.

I can't tell but is c11 oriented in the correct direction? This wouldnt affect your bypass it would have a impact on the effected signal.
« Last Edit: March 20, 2012, 07:46:22 AM by jimmybjj »
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