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May 22, 2015, 07:46:05 PM
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: black_orpheus
DIYstompboxes.com  |  DIY Stompboxes  |  Building your own stompbox  |  [Need Help] Debug Smoothie baby board 0 and 1 Guest are viewing this topic. « previous next »
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: [Need Help] Debug Smoothie baby board  ( 245 )
fair.child
: 60


[Need Help] Debug Smoothie baby board
« : May 06, 2015, 02:34:23 AM »

Hi folks,

I just finished wire the smoothie (Phase 45)from madbeanpedals.com and it seems that I got problem. Let me briefly explain what's going on

1. I checked the true bypass signal and it works but somehow when I try connect into the Smoothie it doesn't give me any output. Any thoughts ? I started to look at the voltage out of 2N5952 matched out (not following 2N5457 but I saw the notes about flipping the transistors so I got that) and showed 1.792V for two outs

2. I haven't gone thru check each of pin outs TL072CN but as far as I know I got 1.4V - 1.7V at the pin one. I need to go thru with this and provides later some more details thou. And also I checked the 9V in to the each of TL072 so that things work. Any thoughts ?

3. I'm thinking about using debugging tools but if somebody can help me out then I wouldn't mess with debugging tools.

Perhaps I missed something.. Any thoughts, opinions, comments will be highly appreciated. Oh by the way this is my second build of baby boards so I can consider my self as a starter with this although I've been successfully built couple pedals



Thanks
« : May 06, 2015, 02:40:25 AM fair.child »
MaxPower
: 133


Re: [Need Help] Debug Smoothie baby board
« #1 : May 06, 2015, 07:53:16 PM »

Not much to go on. A schematic would help. I would start by measuring dc voltages at various junctions (bases, emitters, collectors, op amps ins, outs, etc.) to see if the expected voltages are present. If you don't know what the expected voltages are, figure them out mathematically, search on the web for them, or use a program like Tina-ti or LTSpice to simulate the circuit and find out what the expected voltages should be. Don't expect the measurements to be exactly the same as a real world circuit, but they should be reasonably close.

The audio probe is also a good idea. Follow the audio signal through the circuit until the problem arises (signal disappears, etc.). Then you have a pretty good idea of where the trouble lies.

What lies behind us and what lies before us are tiny matters, compared to what lies within us - Emerson
anchovie
: 1738

James H, UK


Re: [Need Help] Debug Smoothie baby board
« #2 : May 07, 2015, 01:56:47 AM »

http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

- Guitar built from parts
- Random strings to make a full set
- Any pick that I can find on the floor
- Some pedals that I built
- My all-tube amp head that I built out of parts in my spares box
- Cheap Marshall 4x12 with better speakers fitted
Luke51411
: 667


Re: [Need Help] Debug Smoothie baby board
« #3 : May 07, 2015, 02:16:48 AM »

Did you rock it before boxing it? It could just be an issue of an incorrectly wired switch. What 3pdt scheme did you use?
fair.child
: 60


Re: [Need Help] Debug Smoothie baby board
« #4 : May 08, 2015, 04:40:57 AM »

For couple more details... Thanks anchovie for reminding me..Sorry for not following the rules guys  :icon_smile: :icon_smile: :icon_smile: :icon_smile:

(1) Project Name : Smoothie 2015 baby board madbeanpedals

(2) General description of the problem
Nothing from output signal

(3) Steps that you have taken to try to resolve the issue

1. I checked the true bypass signal and it works but somehow when I try connect into the Smoothie it doesn't give me any output. Any thoughts ? I started to look at the voltage out of 2N5952 matched out (not following 2N5457 but I saw the notes about flipping the transistors so I got that) and showed 1.792V for two outs

2. I haven't gone thru check each of pin outs TL072CN but as far as I know I got 1.4V - 1.7V at the pin one. I need to go thru with this and provides later some more details thou. And also I checked the 9V in to the each of TL072 so that things work. Any thoughts ?

More details on pinouts voltage after I used audio debugging tool

IC 1
Pin 1-1.529
Pin 2-2.75
Pin 3-1.63
Pin 4-0
Pin 5-3.29
Pin 6-3.29
Pin 7-4.61
Pin 8-9.17

IC 2
Pin 1-2.06
Pin 2-3.3
Pin 3-3.3
Pin 4-0
Pin 5-4.53
Pin 6-4.62
Pin 7- Fluctuating from 4.62 to 7.21
Pin 8-9.23

3. I'm thinking about using debugging tools but if somebody can help me out then I wouldn't mess with debugging tools.
*I'm suspicious with IC 2 pin 7, am I getting correct output ? It has been really painful to take off the IC because I didn't put any socket before. I tried to debug and followed from the input and output side. I start to lose the signal on pin 1 IC 1. I got the signal after C1 10n , R1 10k and I didn't hear any out from IC 1 out 1. I changed the TL072 and socket ed the IC, however I still got the same issue. Losing the signal.  :'( :'( :'(

Perhaps I missed something.. Any thoughts, opinions, comments will be highly appreciated
fair.child
: 60


Re: [Need Help] Debug Smoothie baby board
« #5 : May 08, 2015, 04:46:15 AM »

Not much to go on. A schematic would help. I would start by measuring dc voltages at various junctions (bases, emitters, collectors, op amps ins, outs, etc.) to see if the expected voltages are present. If you don't know what the expected voltages are, figure them out mathematically, search on the web for them, or use a program like Tina-ti or LTSpice to simulate the circuit and find out what the expected voltages should be. Don't expect the measurements to be exactly the same as a real world circuit, but they should be reasonably close.

The audio probe is also a good idea. Follow the audio signal through the circuit until the problem arises (signal disappears, etc.). Then you have a pretty good idea of where the trouble lies.

To be honest, I'm too lazy using multisim but that's good thought I really appreciate it thou  :icon_smile: :icon_smile: :icon_smile:. I tried to probe with with audio probe. Not sure whether should I get an output first from pin 1 IC1 TL072. I assume that's the first IC output and I thought that I should get an output from there but I didn't get anything.

So I came with conclusion to look over the old documentation from madbean. It says that the 4.7 Zener diode can be replaced with 10k ohm resistor. I pulled up the zener diode and socket the IC 2 (really painful to take it out maybe because I used to much silver bearing solder. I used desolder braid to take it off)

I haven't checked yet the voltage coming out from Gate Source Drain of two 2N5952's matched. I'll look it up for the next

I'm also thinking to check the continuity whether there's missing connection. Let me know if you have any thoughts
fair.child
: 60


Re: [Need Help] Debug Smoothie baby board
« #6 : May 08, 2015, 04:48:37 AM »

Did you rock it before boxing it? It could just be an issue of an incorrectly wired switch. What 3pdt scheme did you use?

The 3PDT scheme I'm using is from madbean the center lug is the input to the board. True bypass working and I pulled the board out and checked with audio probe. Indeed the problem is from the board








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