Help me debug this???? PLEASE!!!

Frequent questions about dead or faulty pedals. Whether you repair, mod or build pedals, debugging is important. Threads about general debugging problems irrespective of the circuit involved...

Help me debug this???? PLEASE!!!

Postby holio cornolio » 14 May 2008, 21:20

This is my first try at doing anything on stripboard. It's supposed to be the HAO Rust Driver. I've built it up according to this diagram
Presentation1.jpg
, and then wired it into an enclosure without any switching, just to check that it works and, well.... it doesn't. Nothing, NADA, zero. So I'm sure i've done something stupid. Can anyone help? The only variations from the diagram, are C500K pot instead of B500K, and 0.068uf input cap instead of 0.056uf. I've checked voltages but don't really know what I'm looking for. I get 9 ish volts everywhere from the 9v input (no shit!) to pin 8 on the IC, and 4-5 V everywhere else I checked.
P1020738.jpg
P1020737.jpg
P1020736.jpg


Can anyone see the obvious mistake???
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I have literally NO idea what I am doing.
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Re: Help me debug this???? PLEASE!!!

Postby bajaman » 14 May 2008, 21:31

where have you connected the ground wire from the board to???
It should go to the earth pin on the input socket, not the ring pin!!!
Only the black batterry terminal should connect to the ring on the input socket.
When a mono input plug is inserted in the input socket it connects the ring and earth pins, thus providing a solid earth return for the battery.
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Re: Help me debug this???? PLEASE!!!

Postby holio cornolio » 14 May 2008, 21:39

the input plug is a mono plug (just what I had lying around) so there's no switching, but both ground from the board and battery negative are connected to the input earth pin. there's power getting to the board, at least my multimeter says there is. just no noise from the pedal....
I have literally NO idea what I am doing.
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Re: Help me debug this???? PLEASE!!!

Postby rocklander » 14 May 2008, 22:05

hard to see exactly from the size of the pic, but P1020738.jpg it looks like the vero cuts have some loose scraps - perhaps shorting something there?
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Re: Help me debug this???? PLEASE!!!

Postby bajaman » 14 May 2008, 22:21

Yes check the vero ends especially.
ALSO - what is the opamp you are using?
Is it a single or dual type??
It should be a dual type!!
good luck
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Re: Help me debug this???? PLEASE!!!

Postby Greg » 15 May 2008, 01:22

Check carefully for solder between the tracks with a magnifying glass as well.
I don't mean to be rude, but the soldering looks a bit messy... it's easy to have a short across the tracks, esp. if you have any frayed wire hanging thorugh, etc.
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Re: Help me debug this???? PLEASE!!!

Postby holio cornolio » 15 May 2008, 09:34

OK thanks all, still not working, but some observations. I've checked the strips and cleaned up a bit (messy soldering, how dare you!!! :lol: ) I've run a craft knife down the gaps to clean up, and all looks fine. Still no joy though. However, when I turn the pot, I get a small amount of static crackle (fairly faint) and also when I touch anything on what is nominally the input side of the board, I get a sort of very faint mousey squeek. Not the tracks, just the components. Yes I am using a dual opamp, specifically an LF353N, but also tried LF412 which was the same.
What I don't get is that the pot on this diagram appears to be connected to earth on both sides (lugs 1 and 3). Can that be right?
I should get the rest of the proper parts for this in a few days, but I would have thought C500K pot would have worked in place of a B500K?
I've seen a PCB layout for this device which appears to put the input source on the other side of the opamp, could this be the issue? I.e, the wrong input for the opamp being used?
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Re: Help me debug this???? PLEASE!!!

Postby floris » 15 May 2008, 09:44

You're right about the vol pot, it seems to be connected to ground on both sides. That can't be right! The layout says to be unverified and is clearly wrong. Also I see no component values which makes it hard to check.
Perhaps you can post the schematics, that would help?
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Re: Help me debug this???? PLEASE!!!

Postby whammy » 15 May 2008, 09:49

Do you have a schematic?
The vero layout doesn't agree with MarkM's pcb layout at least - it has a resistor between ground and pot lug 3.
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Re: Help me debug this???? PLEASE!!!

Postby holio cornolio » 15 May 2008, 10:09

The values are as per this diagram, except that one or 2 resistors are swapped.
HAO_RustDriver_LAYOUT.gif
I'll try and upload the proper one tonight when I can find it. One other thing I have noticed is that I have a couple of resistirs which should be 100K, reading 70K and 33K, so maybe a bad batch or dodgy technique?? Should still work though right? :hmmm:
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Re: Help me debug this???? PLEASE!!!

Postby holio cornolio » 15 May 2008, 10:12

whammy wrote:Do you have a schematic?
The vero layout doesn't agree with MarkM's pcb layout at least - it has a resistor between ground and pot lug 3.

Should pot lug 3 maybe go to row f? would that make sense???? Then do a track cut at 4F?
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Re: Help me debug this???? PLEASE!!!

Postby holio cornolio » 15 May 2008, 10:37

DEBUGGED!!!!!!! :applause: :applause: :applause: :applause: :applause:
Moved pot lug 3 to row e (not f) and she's working a treat and sounding sweet too
Special thanks to Floris for confirming my suspicion about the layout, you're a mother loving genius!!!! thanks really!! :hug: . I'm really pleased to have sorted this. I haven't been this proud of myself since the birth of my kids!!!! :applause: :applause: :applause:
I'll amend the layout tonight and post here, including component values etc. This is sweet sounding already, but I'm going to jigger about with diodes and ICs now. I've got some schottkys I'm jonesing to try out !! YAY ME, YAY all the people at freestompboxes! I'm so happy!!!!!! :applause: :applause: :applause:
Last edited by holio cornolio on 15 May 2008, 10:41, edited 1 time in total.
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Re: Help me debug this???? PLEASE!!!

Postby whammy » 15 May 2008, 10:40

holio cornolio wrote:The values are as per this diagram, except that one or 2 resistors are swapped.
HAO_RustDriver_LAYOUT.gif
I'll try and upload the proper one tonight when I can find it. One other thing I have noticed is that I have a couple of resistirs which should be 100K, reading 70K and 33K, so maybe a bad batch or dodgy technique?? Should still work though right? :hmmm:


Are you measuring them in situ ?
If yes, you're probably getting a false reading.
Glad it's wotking.
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Re: Help me debug this???? PLEASE!!!

Postby holio cornolio » 15 May 2008, 10:43

whammy wrote:
holio cornolio wrote:The values are as per this diagram, except that one or 2 resistors are swapped.
HAO_RustDriver_LAYOUT.gif
I'll try and upload the proper one tonight when I can find it. One other thing I have noticed is that I have a couple of resistirs which should be 100K, reading 70K and 33K, so maybe a bad batch or dodgy technique?? Should still work though right? :hmmm:


Are you measuring them in situ ?
If yes, you're probably getting a false reading.
Glad it's wotking.

yes in situ. most reading there or thereabouts for value except these 2, but I think you're right!
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Re: Help me debug this???? PLEASE!!!

Postby bajaman » 15 May 2008, 10:43

:applause:
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Re: Help me debug this???? PLEASE!!!

Postby floris » 15 May 2008, 16:20

Nice work! :D
> Moved pot lug 3 to row e (not f) and she's working...
Right, row E on the left side connects via R7 & C4 the opamp A output on pin 1. Good one!
I hate tracing through a stripboard, I find it very confusing and mentally difficult. Much rather see proper schematics...
So the rest of this stripboard layout is ok then?

Now go and play that sweet guitar music! :D
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Re: Help me debug this???? PLEASE!!!

Postby modman » 29 Jul 2009, 17:40

Corrected schematics moved to the Rust Driver thread, it's exactly here

Always work from a verified schematic, not just from an odd layout :wink:
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