Neovibe Debug Help

[Jdansti]

If the sheet says 330pf, the marking on the cap should be 331.

Here's the run down:


NAME      VALUE          MARKING            ALT UNITS
C4             330pf                331                   0.33nf
C12           470pf                471                   0.47nf
C15      0.0047uf                472                     4.7nf
C5          0.015uf                153                      15nf        
C26            0.1uf                104                    100nf
C9            0.22uf                224                    220nf

[tr1p1n]

If the sheet says 330pf, the marking on the cap should be 331.

Here's the run down:


NAME      VALUE          MARKING            ALT UNITS
C4             330pf                331                   0.33nf
C12           470pf                471                   0.47nf
C15      0.0047uf                472                     4.7nf
C5          0.015uf                153                      15nf        
C26            0.1uf                104                    100nf
C9            0.22uf                224                    220nf

Mouser sent me the wrong caps then. One is definitely 470J and the other being 330J.

[Jdansti]

Yep. Those are off by a factor of 10.

[tr1p1n]

Yep. Those are off by a factor of 10.

Could this explain my massive volume drop? Not sure how clear you are with the neovibe but is there a difference between 50V DC and 50V AC? So far I know there 330, 470pf 5% tolerance with 50V rating. Either one OK? May seem like a stupid question but I really wanna be sure. And would it make a difference between 50V or 60V rating? either would work? I kinda don't want to buy the same ones in case they mix them up again.

[R.G.]

Could this explain my massive volume drop?

Probably not. Your massive volume drop is from some undiscovered short, open, bad solder joint, wrong component placement or orientation, etc.

Not sure how clear you are with the neovibe but is there a difference between 50V DC and 50V AC?

Yes.

So far I know there 330, 470pf 5% tolerance with 50V rating. Either one OK?

Either one is OK in this circuit.

And would it make a difference between 50V or 60V rating? either would work?

Either would work. You just have to have enough voltage rating. Beyond that, it works fine - even if more voltage is more expensive.

[tr1p1n]

Short or open? Any thoughts on what I should be looking for on that? Or explain to me how this happens? As for bad solder joints, I re-flowed them all, I'll check em with a magnifying glass now. And for the wrong component placement or orientation, as of now I am 100% sure all components are right and oriented correctly. Aside from the 330pf and 470pf of course.

[Jdansti]

I kinda don't want to buy the same ones in case they mix them up again.

Call Mouser and tell them what happened. They'll most likely send you the correct parts at no charge.

[tr1p1n]

I don't have a problem with re-buying them, it's just the flat rate 6.95$ shipping for 50 cents worth of parts gets kinda old. Are you familiar with the neovibe at all? In case you are, I guess now would be the time to buy the wet/dry mix trimmer seeing as were almost there. Any ideas on what size would fit?

[lonewolf]

on a PCB a short usually is a result of a solder bridge which happens when 2 points connect that shouldnt..look for those with a magnifier or a voltmeter.clean them with a braid then re-solder...an open is the reverse of that..a standard size trimmer should fit that board..you can look at them at radio shack to check the size although they dont sell the correct value..with the trimmer , when you turn it all the way one direction you will hear only the dry signal,the other the wet signal,adjust it for the strongest effect..

[tr1p1n]

So I looked everywhere for this short/open, can't see any bridges. Checked continuity, all is where it should be and there isn't any where's there not supposed to be but could a bad solder joint still show continuity?. All parts are correct and oriented as they should be (aside from the 2 caps which I'll get soon). Wiring is correct and the only thing that is wrong is the caps and the voltages in the LFO (guessing that's what you call the bottom part of the circuit). Could the voltages explain anything? or at this point do they not even matter because the whole bottom half of the circuit works fine. I know something really obvious is going on but I fear I'm to much of a rookie/amateur I'd say to find this. In my eyes everything looks OK, but then again it's clearly not. For now I'll keep chugging along, checking and re-checking. There's something I'm overlooking here.  As for the wet/dry mix trimmer, it's OK (when I reach this point) to find the best phasing and just leave the trimmer there? I got a 220K but It's the same size as the other trimmer so I guess I'll just bend the leads to fit. Reason being I was asking on sizes. Forgot to mention, as for the markings on the other caps they say .22K or .0047K, same as uf? Or not the same rather it's just the way they mark it? May seem like a silly question but I'm trying to be sure on everything.

[lonewolf]

you could have a hairline crack or defect in one of the traces somewhere on the PCB or you have missed something else..I have done that..something so simple and is staring you right in your face.all you can do is keep looking!.if you install the mix trimmer you can turn it all the way one direction to hear the dry signal..then the other way to hear the phase signal..maybe you could isolate a problem that way..to determine if the problem is in the dry or effect side of the circuit..as long as you can get the leads in the holes it should work fine..of course you will need to remove the 2 100k resistors(R35/36)..and usually when there is a letter on a cap it is a voltage rating..

[R.G.]

...and usually when there is a letter on a cap it is a voltage rating..

Tolerance rating. J is 5%, K is 10%.

[tr1p1n]

Got the new caps, they say the same thing though. 330J and 470J, maybe they are right? Put in the R35 & R36 trimmer, when I have it turned all the way towards 1, I can definitely tell the effects are working. And the volume is noticeably louder too, but nothing to big. The other side, being 3, I can't get any sound from there. Is the problem in my dry side?

[R O Tiree]

I had a similar problem years ago - kept getting the wrong caps, delivered by courier, 3 times on the go.  In the end, the Quality Assurance guys went and looked at the parts bin.  Turns out some work-experience kid had dumped a few thousand caps in the wrong bins.  He had a miserable couple of days sorting it out.

Can you buy/borrow/steal or get hold of a multi-meter that will measure capacitance?  Even relatively cheap ones that say they'll measure caps will be able to get down as far as 330pF.  It might not be able to read 33pF.  It's likely that if it says "330pF" or close enough to it, then it's telling the truth.  If it can't get a reading, then you've probably got a 33pF.

What's the Mouser Part No?  We'll probably be able to tell from the datasheet whether this manufacturer has decided to fly in the face of an industry standard and do their own thing.

[lonewolf]

so when you have it turned to the Left you can hear a vibrato that speeds up and slows down with the speed control and gets more intense with the depth control,and all the way to the Right you have no sound? you should hear a dry signal..if not the problem is somewhere in that circuit Q1,2,3..the dry signal comes out C18 which is the output cap..you should be able to isolate where the signal stops with the audio probe..check both sides of the output cap and work your way backwards..330J=33pf/5%..470J=47pf/5%
by the way..330pf=331..470pf=471...J=5%..also C4 is the one to start with... the 330pf in the dry signal side of the circuit..also ..make sure the spdt switch is set to chorus NOT vibrato..on the vibrato side you wont hear the dry signal..you should do that first

[tr1p1n]

I had a similar problem years ago - kept getting the wrong caps, delivered by courier, 3 times on the go.  In the end, the Quality Assurance guys went and looked at the parts bin.  Turns out some work-experience kid had dumped a few thousand caps in the wrong bins.  He had a miserable couple of days sorting it out.

Can you buy/borrow/steal or get hold of a multi-meter that will measure capacitance?  Even relatively cheap ones that say they'll measure caps will be able to get down as far as 330pF.  It might not be able to read 33pF.  It's likely that if it says "330pF" or close enough to it, then it's telling the truth.  If it can't get a reading, then you've probably got a 33pF.

What's the Mouser Part No?  We'll probably be able to tell from the datasheet whether this manufacturer has decided to fly in the face of an industry standard and do their own thing.

Mouser part #'s 23PS133
                        23PS147

[tr1p1n]

Regardless of the other caps, I've got the right ones now. As for the audio, probing C18 I can hear audio pass, its low just like everything else. It's fine coming through the input jack but as soon as it switches over to the wire to A1 its really soft. Even throughout the rest of the circuit, gotta turn my amp up loud just to hear it....is that right? Seems like the whole audio side of the circuit is one big volume drop. Plus with the guitar it's really hard to even get an effect outta of it, without the thing up so loud. Any other suggestions? I can't see any open/bad solders, there's continuity to everything. Wiring is OK and all the parts (as of now) are all correct and oriented right.

[R O Tiree]

A1?  Do you mean R1?  Or perhaps Q1 ("Q" is right next to "A" on the keyboard).  I think someone mentioned earlier (RG?) that you might have a problem in the preamp stages.  The gain of that whole area of the circuit (Q1 to Q3) should be about 3, according to the article at geofex that you linked to in your very first post, which probing at C18 should tell you... the signal should be 3 times what you're putting in at the Input!  So, have a real, close look at the values of the resistors around that area, orientation of electrolytic caps, orientation of transistors, solder bridges, broken and/or lifted tracks and bad solder joints (which look dull and crystalline under a powerful magnifying glass).  Until you can get a larger signal at C18, C5 and C6, this is not going to do what it says on the tin.

[R.G.]

I can hear audio pass, its low just like everything else. It's fine coming through the input jack but as soon as it switches over to the wire to A1 its really soft.

Hmmm. Let me see now. Loud enough at the input jack, too soft after the wires leading to A1 - it almost seems like the wires might have a problem.

[tr1p1n]

Re-soldered the wire to A1, now I can get a steady signal all the way through, sounding the same. Doesn't seem to be 3x the loudness as its supposed to be. Re-flowed the joints, measured the resistance, checked orientation, looked for broken/lifted traces, All OK. Still not sure why on effect volume goes, can barely hear my guitar anymore, just a loud bassy hum now that responds to depth & speed. The trim pot all the way to the left doesn't make a difference, nor to the right. Could a transistor be the problem? I measured all of them, they seem OK except Q10 where it's E=5.5V B=5.2-5.4V C=13.4V.....isn't the base supposed to be higher then the emitter?