Build Your Own Clone Message Board

I've just completed one of Barry's SWAW boards. The build is stock but for a couple of parts I couldn't get. I had to get a 6n8 cap at C4, rather than the stock 8n2. I don't think that is causing the problem though. I'm more concerned by Transistors 1 and 2. I was meant to use BC550s in those positions, but I couldn't get those. I looked for alternatives and with some noobish reference to a data sheet, I went with BC549Cs.

Now, on to the problem. I'm so glad I tried out my test rig for the first time, rather than using my power supply. I used a brand new 9 volter and when I plugged it in and tried to play, nothing happened. I thought something might be shorting in the case, so I started shifting the board and pots back out of the case. I did intermittently get sound coming through, then it just stopped. I then looked at the battery and it had changed shape. It was also extremely hot.

Has anyone had this happen before? Are those transistors to blame? Faulty battery? Anything springing to mind for anyone?

Help as always, will be much appreciated.

Sounds like your power rail is connected directly to ground.

Yikes. First thought is you had the battery wired bassackwards. Second thought is I don't know those trannies but you would need to make sure you weren't switching out NPN and PNP and didn't flip the orientation when you should have. Third thought is glad it didn't explode on you if it changed shape

Post some pics if you want. Barry would say post at his site too.

Edit: What CJ said

I can't see anything obvious. Got a couple of pictures of the board, the soggy looking patches are defluxer that I used after the murder of the battery.





I also wonder whether I've misunderstood the wiring diagram. I haven't attached a footswitch yet. I presume that Input Jack is the positive tip of the power supply and Output Jack is the ground? Presumably the blue 3PDT connection is to the input jack and the green is to the output jack.

Looking at the diagram, it does appear that I've not wired anything to the ground pad though. Although that does appear to be on the same copper trace as the output jack connector.

I think that indeed you are misunderstaning the diagram. Your DC jack(power supply) should have the ground going to the GND top left of the diagram, and positive going to the red 9V top right. Where it says Output Jack and Input Jack on that diagram, those are the ground connections gonig to the sleeve of the input and output 1/4 in jacks, not anything power related.

Then for the 3pDT, the blue in "T" on the jack goes to the blue 3DPT on the bottom right of the board, and the green "Out T" to the green 3PDT switch bottom left of the board.

So in the end CJ is right, you had the pos and gnd of the battery directly connected. Good news is I don't believe you will have fried anything on the board.

Also, as an aside, that is really not my prefered 3pdt wiring set up (or grounding scheme for that matter). Check out Stephen's 3pdt wiring thread here for more info: http://www.buildyourownclone.com/board/viewtopic.php?f=9&t=6525 and have a look at the 5th drawing in the first post.

I feel like such a spanner. That's so obviously what the problem was. The worst thing about this, is that I've been really meticulous throughout this build. I've spent a couple of hours, 3 evenings in a row, rather than rushing it. I really wanted to test it last night though and rather than thinking what I was doing, I used my (badly printed and damaged) picture of the layout and guessed. If I'd taken a moment to look at the copper traces or the schem, I'd have seen what a plank I was being.

Providing nothing is shorting, I think moving that green wire to the DC in by the diode should make it work. The test jacks are grounded elsewhere and I presume using the output tip pad as the main ground will work, as that whole area is grounded anyway?

The only positive about this is that I'm actually quite happy about this build again. I was so despondent last night that I wondered why I'd even started building it.

I'm away over the weekend, so I'll have a go at sorting it out next week. Wish me luck.

Good luck mate!

Don't worry about it, your not the first to turn a battery into a mini George Foreman Grill

We all make silly mistakes along the way, its frustrating but you move along and onto the next challenge just that bit wiser. As long the IC's themselves didn't heat up your probably okay with the board.

I did have a poke at the ICs and transistors, once I detached the battery. They don't seem to have heated up at all.

Presumably that battery is a write off?

I doubt any juice got to the circuit. All you did was connect the battery to itself with no resistance. That's why it melted.

Yeah, I'd not use the battery again.

Power supply it is. :p

I'm still having trouble with this. I sorted out my stupid wiring issue and batteries don't fry any more, but the effect has no effect.

I've taken a few pictures, which will hopefully help.






Now, there's no switch attached to this. There are four wires attached to the board which aren't connected to anything at the minute because they'll connect to the switch and ground when this gets boxed up. I connected up the 4 loose wires to the breadboard as follows:

- Blue: This connects to the input jack.
- Yellow: This connects to the output jack.
- Black: This connects to the negative side of the battery, as well as the sleeves (or ring, which ever bit needs grounding) of both the input and output jacks.
- Green: Connects to the positive side of the battery.

I've also checked the ratings of the three transistors:
Q1=615 hfe
Q2=610
Q3=560

The board is totally silent if I ground the jacks and the board. If I remove the ground from the board or the jacks, then I get bypass across the board, but no effect. I presume that something must be shorting or I've wired up something else wrong for that to happen? Unless this pedal can be bypassed by just removing the power supply...

As mentioned before, the transistors are BC549s, rather than BC550s, but surely that shouldn't result in silence?

Help is much appreciated, as always.

Bump.

I don't think the tranny difference is going to give you no effect as long as we are talking NPN to NPN.

I would like someone else to comment on this too, but do a lot of the joints look starved? In particular the IC's ones and a lot of the ones in the middle of the board? All it takes is one bum joint and the board is mute. I'd reflow the joints and touch up any that look thin or starved. It will only take 5 minutes or so.

The other thing with Barry's boards is you need to take a pic of the board in some bright light. Basically put the board up to a light ( I have a magnifier with a light I just set it on, but anything will do and take a pic. Solder side up. The idea is to help show if there is a solder bridge or not. All it takes is a tiny amount of solder on one bridge and the board is silent.

The other things on these boards is the ground plane is an issue. This means the ground plane runs all the way around the board. You can get any solder on this ground plane that should not be there. I know as my first few I didn't pay any attention to it and they didn't work. I had to use some braid to get it off to get the board working.

The one thing we can't know is if something fried on the board on the mishap. This is where I'd use my audio probe to see where the signal dies, assuming one is coming in. I don't breadboard so I can't really help you there.

Oh, pull those IC's in particular and I'd pull the trannies too before you reflow the joints. I assume you double checked the trannies proper orientation or placement.

Double check your grounding. You MUST be grounding from the DC jack/battery ground to the sleeve of both jacks (not the ring, ring is only on stereo jacks) and to the board.

Triple check the orientation of your polarized caps and all diodes, especially D4.

TNs advice on checking the board for bridges is great, on my V6OD i had the most minute bridge that was causing all the problems.

Then next before moving to the Audio probe I would start checking continuity and power with a Multimeter. Is there continuity between the jack tips and the board? Betweel the ground lead of the power supply and the ground plane on the board. Then using the volt meter part of the MM check to make sure you are getting power to the board. Make sure power is getting past D4. Check all the way down the power rail if you can.

From there on to the audio probe and start tracing the singnal path. Hope this helps. Hang in there!!

I haven't been able to do any soldering tonight, but I have checked the orientation of the diodes, polarised caps and transistors. As far as I can tell they're all correct.

I'll break out the iron tomorrow and reflow a few things. See if that makes any difference. I assume there must be some sort of continuity between the jacks, because if I disconnect one grounding wire I get bypass.

Ok, there is something very strange going on here (or my extremely tired brain is not working as usual). If I am understanding right you are doing this all on a breadboard with no switch (footswitch or otherwise) involved?? If this is the case, then there is no such thing as "bypass" as that would be done throught the switch. If you are getting signal from in to out with no switch, it is going through the board somehow. Can you post a pic of the board all hooked up in your breadboard rig?? Also what are you disconnecting the ground from that is making it work? I will have another good look at the existing pics later tonight.

See, on the bypass issue I had the same thought. I just can't understand how the board is getting bypassed. I will post pictures later of the breadboard set up, but just to clarify:

-If I ground the jacks (the inner part which I ground on all my builds, so I'm guessing it's the correct one) and the board as expected, then it is totally silent.
-If I pull the ground wire from either the board or the jacks out of the breadboard, then I get a bypass effect.

Here's a picture of the breadboard set up. I haven't had time to break out the soldering iron and reflow anything yet though. Can anyone spot anything obviously stupid about what I've done?

IT LIVES!

Nice work, way to stick with it. What was it in the end??

I'm not totally certain. Last night I went over the whole board, adding more solder in some places and removing some from others. I checked all over for solder bridges, but I didn't see any. I put it all back together on the breadboard and it didn't work. For whatever reason I decided to check that I'd wired the pots up correctly (no idea why I never thought of checking this before) and I noticed that on one pot I'd reversed lugs 1 and 2. I took them both off and flipped them, but I didn't think that would make any difference because I thought they were both going to ground anyway. I also decided to connect up a DC jack and stop using a battery. I did that and low, there was funk.

So, I think it must have been one (or possibly several) of three things. Either:

-The flipped lugs were not just both going to ground, so I was grounding out the circuit (seems quite likely).
-Flipping the lugs removed a solder bridge I had misses.
-The battery was knackered.

Happily, I think I can fit it in the enclosure I wanted. I've put felt on the back of the board, so I can really squeeze it onto the pots and nothing will short. Just need to get some footswitches in and I can close this one up and post it as completed.

Thanks for the help guys.

Would you mind explaining this in different words please TN? I have some of Barry's boards to build, so I'm trying to understand what exactly it is I need to avoid doing. (I do know which bit is the ground plane.)

I really hope he just means that you mustn't let anything that you don't want grounding touch it. Otherwise this may some new evil I have never before considered.

Hog, I'll show you a pic below of my Super Drive 70's from Barry to explain it best. Prior to this point I'd only done double sided PCB's. So the only "bridge" I had to worry about was a bridge between components. So I happily went about my business and only worried about sloppiness I guess between components. The best way I can explain is take that joint below the "e" in Drive. Go down an inch and it is sort of all by itself. Notice I did not get any solder beyond that little circle that is etched. Had I gone over the circle and got into that open blank copper space that is a ground plane that is sort of surrounding everything. It will short the circuit. Up to that time, I figured who cares if I go outside the circle as there is not another component I need to worry about. Now if one of your connections is a ground connection anyway then I don't think it matters in that case. Anyway, I had to clean up some things once I realized that.