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Flabulanche power section

Started by ThatGuyThere, July 02, 2019, 01:18:15 PM

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ThatGuyThere

I am finally building the Flabulanche pcb that I had sitting around.  I am having problems with the voltages not getting to the LT1054, and consequently, nothing else is happening on the board.  As you can see from the schematic, I have about 9 volts after D2.  I am getting 8.99 v on the + side of the 100 uF (c13).  On the 15v Zener (D3) I get about 1.87 v to 2v.  It fluctuates a little.  After D3, I get almost nothing  on C14 has 0.02 volts.  It almost seems like there is an issue in the trace between the C14 and D3 and then again between D3 and Pin 8 of the IC. Or is the IC messed up?  Would there be a way to jumper between C14 and Pin 8?  Would that be bad?  Previously, I did not put the Zener in D3 because people said that it was optional.  I was still getting these issues.  Consequently, I ordered a lot of Zeners only to find out that it did not really change the problem.
The IC measures as follows:
Pin1:  0.031v
Pin2:  0.003v to 0
Pin3:  0
Pin4:  0.074
Pin5:  0
Pin6:  starts at 1.3v and bounces down to about 0.06v
Pin7:  0.018v
Pin8:  -0.004v
None of these voltages are making any sense to me.  D4 and D5 have nothing going on.  Except, that D3 has a voltage that sort of fluctuates around 1.8 to 2 volts.  I have gone through and reflowed the pads for all of the spots described above and am not getting any significant changes.  What else should I do?  Thank you for your help.
Tyler

ThatGuyThere

Here is a pic of the guts.  I know, I should have rocked it before I boxed it....stupid me.
Tyler

midwayfair

the only way you can possibly get different voltages on D3, C13, and C14 are if multiple traces are messed up, which can happen, especially because I'm really not sure what's going on with your C13 ... Use your continuity setting on your meter. You're best off removing the pedal from the box in case you have to do some surgery on the board.

You can pull the chip to see if the pedal works on 9V, but that won't solve the problem above.

ThatGuyThere

Hi there,
So there seems to be some continuity issues between C13+ and pin 8 of the IC.  I am starting to wonder if the traces are bad?

Option 1:  Is there a simple way to jumper the C13 to the C14 to the IC (assuming I skip the zener)? 

Option 2:  Could I use the 3PRR and bypass the whole voltage pump section of the board?  I would assume that I would just tie in at D4?  But still not sure how to resolve the issue of the blue trace from pin2 on the IC to C15-.  Thoughts?

Option 3:  Scrap the board and hope someone has another pcb?  I do not know how to etch a new board or anything like that.  I would really like to use the enclosure that I made and was pretty stoked about this type of circuit....so- bummer.

Option 4:  Try putting a different madbean pcb in there that uses 3 pots and a switch, sand down the enclosure and start over....:(

Any thoughts would be very helpful.  Thanks for your time.

Tyler

ThatGuyThere

Success!  So I figured that there was a bad trace before the IC and did some testing with some jumpers.  In the end, I jumpered (is that a word?) the positive leg of the 100uF C13 capacitor to the bottom of the board side of pin 8 on the IC.  I had used a socket and there was enough of a pin coming through that I was able to wrap a bit of wire around it and quick solder it all together.  Obviously, I had to bypass the zener diode and the 100n C14 capacitor.  I understand that the zener is optional protection, but what are the downsides of losing the C14?  Should I still try to solder a 100n cap to the jumper and to ground somewhere?  I was not hearing a lot of issues when I was playing through it. 
BTW, it is a really nice sounding pedal!  I can't wait to spend more time making music with it, as opposed to troubleshooting it.
Tyler