Neovibe Debug Help

[tr1p1n]

Un power the board. Set your meter to read ohms and verify that the pads for the collectors of Q11 and Q12 show very low, almost zero ohms, to each other and to one side of the bulb.

Check the base pad of Q11 for resistance to Q11 collector, Q11 emitter, and Q12 base and emitter. All of these should show significant resistance, well over 1k ohms.

Check the emitter pad of Q11 for resistance to Q12 base (should be nearly zero), and to Q12 emitter (should be well over 1K).

If all that seems to be OK, put in a new transistor at Q11 and Q12 if you have them, not the old ones in case they have been damaged. If you have only 2N3904s, use them. If you have a higher gain transistor like a 2N5088, use it for Q11.

When this is done, check your soldering under magnification, power up and change to measuring Q11/Q12 voltages again. Post results back here.

I did mention that the trace from R40 to Q11 base is toasted and no longer there. Also Q11 emitter to Q12 base trace too and the emitter to R44 (yeah I messed up bad) Not to mention the little metal rings are missing on both Q11s & 12s emitter and base. So at first I thought the metal contacts not being there (bottom side) was the reason for me not getting any readings. So I went to the top where the rings still remain and couldn't get a reading from there either. Only test I was able to confirm was resistance of the Q11 & 12 collectors to the bulb which seem OK. Other than that, just nothing from everything. I'm not sure if this was a way to go about it but I did stick cut off leads into Q11 base and collector which after some time gave me a reading well over 1K. Only test I did like that being unsure whether the pads themselves need to be measured. So at this point I'm assuming I've damaged the board or something of that sort to the point of no return. I'll just wait for your input for now, maybe there is another way to definitively answer your questions.

[lonewolf]

what you have damaged is repairable,but use sockets and resistor wires to do the repairs..dont just keep soldering/de-soldering..those boards will self destruct

[tr1p1n]

what you have damaged is repairable,but use sockets and resistor wires to do the repairs..dont just keep soldering/de-soldering..those boards will self destruct

Sooo I was supposed to use resistor wire from one point to another to repair this? I've been just putting in the transistor then bending its lead to where it has to go then soldering it to that. Is this the wrong way and the reason why we've been getting the same results over and over again?

[R.G.]

I did mention that the trace from R40 to Q11 base is toasted and no longer there. Also Q11 emitter to Q12 base trace too and the emitter to R44 ...  So at this point I'm assuming I've damaged the board or something of that sort to the point of no return. I'll just wait for your input for now, maybe there is another way to definitively answer your questions.

Board repair is needed. I can do a better job of telling you what to do if you can take high quality photos of the Q11/Q12 corner of the PCB and post them.

Yes, you will need to put in sockets for the transistor pins and repair the traces before any of this will get better.

[lonewolf]

you have been going round and round over the oscillator part of this but I was wondering ..does it pass a clean signal? you can check the phase circuit by removing the light box and in a dark room wave a flashlight over the ldr's and you should hear it phaseshift(with your guitar connected)..and bending the leads of transistors is not a good idea...

[tr1p1n]

I did mention that the trace from R40 to Q11 base is toasted and no longer there. Also Q11 emitter to Q12 base trace too and the emitter to R44 ...  So at this point I'm assuming I've damaged the board or something of that sort to the point of no return. I'll just wait for your input for now, maybe there is another way to definitively answer your questions.

Board repair is needed. I can do a better job of telling you what to do if you can take high quality photos of the Q11/Q12 corner of the PCB and post them.

Yes, you will need to put in sockets for the transistor pins and repair the traces before any of this will get better.

I can't get any photos at a higher resolution then the ones posted before and I have zero confidence in my ability to repair a trace (not saying I won't try) but I'm almost certain I'd just ruin things even more. I hope there is a simpler way to fixing this other then buying sockets and/or conductive pen.

[tr1p1n]

you have been going round and round over the oscillator part of this but I was wondering ..does it pass a clean signal? you can check the phase circuit by removing the light box and in a dark room wave a flashlight over the ldr's and you should hear it phaseshift(with your guitar connected)..and bending the leads of transistors is not a good idea...

The only time I can get this thing to pass a clean signal is if I physically hold both jacks in my hand, as in the guitar chords that plug in. Otherwise just this loud annoying hiss, not the wahhh as before due to the light not flashing anymore I think. Maybe I have the jacks wired wrong or maybe I screwed something up other then the oscillator part. So I assume there isn't a point in checking (yet).

[lonewolf]

I can tell you forget the conductive pen..I assume you are talking about the radio shack one..if you are not sure you can repair the board then dont..you may want to have someone do it for you...as for the pics...take some close-ups of the portion of the board he was talking about...you must have a open ground or some other problem in the audio path of the circuit..even with the oscillator problem it should pass a signal

[tr1p1n]

Well the clarity isn't the greatest, but I took a few photos. Hopefully you can reach a proper solution from them.

http://imgur.com/Jc7Rq,aKhEJ,dLamA#0

[twabelljr]

If you have a Radio Shack nearby this bus wire works great for repairing traces and is really nice for perf work also:
http://www.radioshack.com/product/index.jsp?productId=2102500
Cut a piece and solder to your component or socket and shape it to follow the trace to the next appropriate component. It is thin and very pliable. When doing perf I like to bend the end 90 degrees and cut it short and slide it up in the same hole as the componenet. Component from the top, short end of bus wire up through the bottom of the same hole and you basically have a new ring. The end can be squeezed and flattened some if necessary. You can tack it down to good sections of the traces to hold it in place. It is thin enough to wrap a tight loop around a component leg also. You could also pick up a few 2N3904's although they are a bit over a dollar apiece, but you will be ready to repair and continue debugging today. A roll of the bus wire lasts a long time. Bending the legs like you did is a fine way to connect components also. Good luck. I have been following this thread with interest and am looking forward to this thing working for you!

[R.G.]

Well the clarity isn't the greatest, but I took a few photos. Hopefully you can reach a proper solution from them.

Image 3 tells me much of what I need to know. There are no traces to the base and emitter of Q11 and to the base of Q12. It can't work. I mistakenly thought you'd repaired the missing traces already.

I buy transistors by the hundreds when I buy them, as they're about $0.06 to $0.10 each that way, and so I view transistors as expendable. I don't bother with sockets; if I need a transistor removed and it's a normal "jellybean" transistor like the 3904, or my favorite 2N5088,  I just clip the body off and take the leads out one at a time. It's easier on the PCB, which is much more expensive and harder to repair. Sockets are remarkably expensive, more so than transistors, so I don't bother with sockets unless I absolutely know I'm going to be swapping out transistors for sound tests, which doesn't happen much. This is all just to let you and other readers know the reasoning behind why I don't mess with sockets.

If I were doing the repairs, I would stick new transistors in from the component side, with the leads in the correct holes. I would also check the pinout of the transistors I was using to make sure it was the correct pin in the correct hole.

Then I would bend each transistor lead over parallel to the PCB surface to the nearest solder pad which was a correct connection for it, trim the lead to length and solder it onto the pad. In this case, it's easy. The collectors of Q11 and Q12 appear to be going into undamaged pads on the + power supply. The base of Q11 can bend over to the end of R40. The emitter of Q11 can bend over to the base of Q12, and these two can be overlapped and soldered with no trace or pads. The emitter of Q12 can be bent over and soldered to the nearest pad of R44. No bus wire or other fancy stuff needed.

Take a look at this approach and see if you think it's feasible for you to do.

[tr1p1n]

First off, R.G you weren't mistaken, I did have the trace repaired (or so I thought). Anyways, I had Q11 & 12 soldered almost exactly how you said before I removed them except as before I bent the Q12 emitter to the Q11, not the other way around like you said. So after soldering I powered her up and the first thing I noticed was the bulb wasn't on and there was no voltage to Q13. Thought Q13 fried or something and that was the reason for the bulb not being on. Replaced Q13 and nothing, still no voltage. So next I de-soldered the bulb, replaced the leads with some wire then powered her back up. Light came on and actually started to oscillate again (think that's what you call it), responds very well to depth & speed pots too. Was to afraid to take voltages (as of now haha) in fear of damaging it again. I'll wait for your input before I go ahead and take measurements. But as of now the bulb works, reacts well but I cant seem to get a bypassed signal without holding the two jacks together like I said before. Maybe I have this wired wrong? But at least now when I hit the DPDT switch I can hear the bulb oscillating through my amp, still no guitar signal. This was the first sign of hope in weeks  Hopefully we can sort the rest out soon.

[R.G.]

Good work! That's how the thing should be acting, and it's clear by the bulb lighting, pulsing, and responding to speed and depth controls that the lower half of the PCB is now working.

It's also good that we know that it used to pass signal on the top/signal half. That means that the problem is probably something trivial, like wiring.

First off, check the wiring against the wiring diagram - yes, again. I know it's repetitive, but it's the first thing to check. It's best if you can print the wiring diagram, trace each wire on the PCB and parts, and mark off on the printed diagram with a colored marker or some such to ensure not getting confused about which wire has been checked before.

[tr1p1n]

Well everything is wired accordingly, at least I think so. Is there any special way to wire the jacks or DPDT? As for the pots, do I hold them with the knob face down when comparing them to the diagram?

[R.G.]

Well everything is wired accordingly, at least I think so. Is there any special way to wire the jacks or DPDT? As for the pots, do I hold them with the knob face down when comparing them to the diagram?

Depends on which diagram. I used to always show pots from the non-shaft/knob side for clarity. Other people show it the other way. Mostly, for the immediate problems you have, this does not matter.

You need to make yourself an audio probe, about which see the many references in this forum. This is just a guitar cord with a capacitor to block DC that lets you use your guitar amplifier to trace audio signal. I like my variation, which is an enclosed phone jack with a ground clip on the sleeve contact and a capacitor on the tip contact. This means that you don't have to cut up a guitar cord to use it for an audio probe, but there are other ways too.

Read up on audio probes, ask questions, and get prepared to build and use one.

[tr1p1n]

Well good thing I already have made one about a week prior to this, never used it though. Of course now I have, using a 1/4 jack to 3.55mm (or something of that sort) with a CD player pumping a signal through the circuit. But is it necessary for the circuit to be on to follow all the way through properly?

[R.G.]

Is it necessary for the circuit to be on to be able to follow the path all the way through?

Yes, the circuit must have power on it to pass signal properly. Any signal coming through with the power off is accidental, and not an indicator that anything good is happening.

and I should be following the schematic all the way to the end right?

Yes, but let me give you a set of points to listen to.
- the input pad, A or A1, about which see the notes for your question below.
- collector and emitter (both!) of Q3
- base of Q4, both collector and emitter of Q5
- base of Q6, collector and emitter of Q7
- base of Q8, collector and emitter of Q9
- base and emitter of Q10
- pads N and M

Knowing whether there is signal at those points will tell you where to look further, if it's needed.

One more question, when the effect is on am I supposed to get signal through both A1 and B or just A1?

B is the input ground pad. There should never be signal detectable there. So if you're using A1 as an input, only A1.

The way I was wired, when I had to hold both the jacks to get my guitar to bypass, A1 was the only pad with a signal coming through (effect off) with the effect on I could hear oscillation (no guitar signal). Other way around and I can't get anything from my guitar (bypassed or effect) but signals in both A1 & B. So kinda unsure which one is right, seems like it should be both A1 & B but then again like I said my guitar doesn't work that way. I may be answering my own question but I'd like to be 100% positive before beginning to trace the audio path.

Then let's be 100% sure of the nomenclature you're using. What schematic and pad lettering are you using? The ones in the project file at GGG?

[tr1p1n]

Took me to long to edit my previous post so you missed it, but I did manage to get a clean bypassed signal, no static. I only had one wire on the output jack, the diagram shows only one. I am using the files from GGG and pads A1 & B. I looked at pictures of completed builds and noticed all there output jacks had a second wire going to ground through the volume pot. So I did that exactly and now bypass works. *I see what happened with the wiring, The project file shows both wires on the output, but the "clear" file that I printed shows only one*. As for turning on the effect, I can hear the oscillation through my amp well but have to turn my amp up really loud just to hear a clean guitar signal, no effect what so ever. I'll go over the audio as I did it early (attempted to) with the circuit off and a CD player pumping audio through it. Could voltages still be screwy? or do you think it's still something with wiring or the audio? I'm not sure what's going on but it feels like were almost there.  

[R.G.]

I only had one wire on the output jack, the diagram shows only one. I am using the files from GGG and pads A1 & B. I looked at pictures of completed builds and noticed all there output jacks had a second wire going to ground through the volume pot. So I did that exactly and now bypass works. *I see what happened with the wiring, The project file shows both wires on the output, but the "clear" file that I printed shows only one*.

Many schematics are somewhat casual about showing ground wires, assuming that this is so basic that it doesn't need said. Sometimes I even fall prey to this myself.

All input/output jacks must have ground connected to the ground terminal, whether it's shown that way or not, unless the design specifically deals with it NOT being grounded. In many effects setups, the input and/or output jack is connected to ground by it being installed into a hole on a grounded metal enclosure, so a real wire is not necessarily connected, or shown.

As for turning on the effect, I can hear the oscillation through my amp well but have to turn my amp up really loud just to hear a clean guitar signal, no effect what so ever. I'll go over the audio as I did it early (attempted to) with the circuit off and a CD player pumping audio through it.

Describe this "oscillation" in some detail. Is it a low, bass hum, a buzzy bass hum, a whining tone? Does it vary with the speed or depth pots? Are you powering this from a switching power supply?

Could voltages still be screwy?

Yes. Remember the onions analogy.

or do you think it's still something with wiring or the audio?

I don't know at this point.

I'm not sure what's going on but it feels like were almost there.

That's true. You're not far. It's hard to remain patient and do the pick-and-shovel work when you get close, but it's important to take it a step at a time.

[tr1p1n]

Rough night for me, but here we go. For the output jack, the schematic is where I first got the idea of there having to be another wire for it shows ground on the opposite lug. Which then lead me to looking at pictures and long story short, we got a clean bypassed signal. As for the oscillation its like a low bass hum, gets louder when increasing the depth and faster with the speed pot. Am I not supposed to hear the oscillation? mind you I do have the light shield off, if that has any correlation. Switching power supply? Well I'm powering this with a 24V DC/100ma wall wart plugged into a power strip. Now about the audio probe, was using the 1uf 50v from the specified parts list for this project, is that OK? I mean it works but when I began to probe, figured I'd do the pads first, A1 works of course. Skipped over to N & M, both get a signal but I got a little frightened when M sparked and the light went out. I'm not sure if this was the cap or the fact that the wire isn't soldered all the way to the board and the sparks came from the exposed wire(probing top side). Regardless we still have signal, the light still oscillates, but it did scare me enough to put a halt to probing and instead move on to measuring voltages (which isn't any better, for me at least). This is how I went about this to avoid any confusion. R13 - 4.1V =  4.5V (what I get). Now for the actual list.

All points that say to 15V source = 14.78V
R13 - 4.1V = 4.5V
R18 - 10.9V = 11.35V
Q5 - 4.1V = 3.35V
R32 - 6.1V = 6.04V
Q10 - 5.4V = 5.5V
R40 - 11.7V = 15.95V
Q12 - 10V = 11.6 - 16V (Goes from 11.6 to 12 something, 14 something then finally 16 before it repeats itself)
C25 - >17V = 27.2V

So there's still something off there, not sure if this has anything to do with the effect.