HELP! Neovibe noob builder... no effect.

[piloto117]

  Hi.  I'm very new at this and consider myself a total noob, so please be gentle.  I started doing this DIY thing a few months back with some of the BYOC kits, got some confidence and picked up a neovibe project. I finally finished building it last night only to find out it didn't fire up! 
  I used the PCB from GGG, parts are all from the "stock list" in the pdf file, all transistors are 3904's.  Bulb is from radio shack 12v 25ma.  No mods, I haven't even added a LED. The bypass works perfectly, but I get absolutely no sound when effect's engaged.  Power adapter is 24v 600ma unregulated, brand new, probed it and it seems to be working OK. Bulb does not light up.
  Mmmm trying to think of some more details...  I'll try to add some pictures as soon as possible.  Wiring I believe is correct (are the pots on the layout looking backwards with the pole on the opposite side?)
  Anyhow, tried to probe for voltage on the transistors this is what I got:

Q1
E= 0
B= 1
C= -10

Q2
E=0
B= -10
C= 0

Q3
E= 0
B= 0
C= 0

Q4
E= -6
B= 1
C= 0

Q5
E= 0
B= -6
C= 2

Q6
E= -5
B= 1
C= 0

Q7
E= 0
B= 2
C= 0

Q8
E= -5
B= 1
C= 0

Q9
E= 0
B= -6
C= 0

Q10
E= 0
B= 1
C= 0

Q11
E= -4
B= 3
C= 9

Q12
E= 0
B= 2
C= 9

Q13
E= 0
B= 3
C= 9

  I'm not sure if I'm probing it properly.  I set my cheap digital multimeter for DCV at 2000m (if I try it at 20 I get no readings, only zeros and minus zeros).

I suspect it's the bulb but I've checked it as close as possible and seenothing wrong with it, is there any other way I can test it?

Suggestions welcome, answers appreciated!

ed.

[vince76]

I'm not an expert at all, but all the voltages seems to be bad.
I built a neovive, it's very simple to make a mistake cause it's a difficult board.
I can say: start from the power section, measure voltages after the diode bridge if you have one in your board, then after voltage regulator, if you have a value that is not 15v you find the firs bad thing, then go to the lamp, and so on, remember to measure the voltages from the pin of a component to ground. The power adapter is 24V DC?
Hope you can resolve
V.

[R.G.]

  Hi.  I'm very new at this and consider myself a total noob, so please be gentle. 

No problem. We all started with exactly the same knowledge of electronics. It's only the guys who started already knowing it all and telling us that who have difficulties here. 

I'm not sure if I'm probing it properly.  I set my cheap digital multimeter for DCV at 2000m (if I try it at 20 I get no readings, only zeros and minus zeros).

A cheap multimeter is fine for this purpose. You need to set it up like this:
- plug the black lead into the minus (-) lead plug hole.
- plug the red lead into the positive (+) voltage hole. Many voltmeters have a voltage hole and a current hole, so you have to get the right one. Test that you did this right by measuring the voltage on a fresh battery where you can see that you got both the voltage and polarity (+ versus -) correct. You'll want the range switch set to either 20V for a 9V battery or 2.0V (maybe what you're seeing as 2000m is 2000 milli-volts) for an AAA, AA, A, C, or D cell.
- Once you get this all lined up, you'll mostly want it set at 20V for the measurements on the 'vibe because the voltage is regulated to 15V or less over most of the board. Only a few parts are over 20V. When you get to those few parts, you want to use the next scale up from 20V.

I suspect it's the bulb but I've checked it as close as possible and seenothing wrong with it, is there any other way I can test it?

In general, for effects made with new parts, not parts scavenged from older junk boards, the parts are almost never the problem. It is very tempting to think this way, and in fact most of our culture about fixing things encourages us to think in terms of broken/bad parts. But the statistics for people building DIY effects  have shown that it's almost never a bum part. It is almost always one of these:
- incorrect part or part value
- right part, wrong place on the board
- polarized parts like electro caps, diodes, transistors, and ICs inserted into the board the wrong way round.
- using different-pinout transistors incorrectly
- inexperienced soldering technique leading to shorts, opens, and/or incompletely soldered junctions
- inaccurate or incomplete wiring
- for home-made PCBs, PCB trace faults, principally shorts
I have found new-bad parts only a few times in over 30 years of building effects. I've seen maybe two of them turn up as the problem in others building effects here.

So, get the multimeter technique lined up so you're measuring voltage well, and we'll go from there. It's probably something simple.

[piloto117]

  Thanks a lot guys.  (It's great motivation to have R.G. backing you up!)  I'll give it a go when I get back home, I'll post some pictures as well and get back to the thread ASAP.  Thanks again!

[piloto117]

  Well, I got back and did what you told me (probed at 20VDC) and I get no readings other than 0.00 or -0.00 on all the transistors.  I checked and double checked all the components to see if I had them in correctly (including the resistors and caps) and then I also checked my solder joints.  Now i know there are a few dark spots on the board because at the time I had a very big tip but the solder joints are all good.  Here are some pics:






















On probing...I'm using the extra square pad below the K and J pads for ground and then with the positive tip I check on the solder joint for E B C on the transistors, but no readings except what I mentioned before...
Now I'm thinking that it could be that the adapter jack:  http://www.smallbearelec.com/Detail.bok?no=666
and the power adapter http://www.altex.com/AC-Adapter-24VDC-600ma-with-21mm-Power-Plug-45-762-P143452C10578.aspx
are not compatible.  Although I did try with other power adapters, but simply I don't have anything over 12 volts.

What do I do next?

[hubble]

that DC jack looks like you havent wired anything to the negative terminal?

[SonicVI]

yep, power jack isn't wired correctly, that could be your power problem

[piloto117]

 

Well, I wasn't too sure on that because it says on the pdf file:

"K and J pads 14 VAC to 20 VAC or 18 VDC to 24 VDC, DO NOT GROUND EITHER WIRE!!! DO NOT LET POWER JACK TOUCH CHASSIS!"

So I thought the two pads K and J should go onthe positive terminals on the power jack....
So you guys think I should place one of the wires to the ground on the jack? Could that be it? Promise my 'vibe won't fry? LOL

[orangetones]

Your vibe won't fry.  Your jack won't ground to the box because it is a plastic jack.  This is the right thing to do.  Hook one of your wires to the negative terminal on your DC jack.   That's it.  Doesn't matter which one either I would suspect as you have a diode bridge in there.

[piloto117]

  EUREKA!  LOL   IT'S ALIVE!!! 

Thanks guys, wouldn't have figured it out by myself!  As I read on another thread..."finished....now tweaking begins!" 


  Makes me feel kinda bad posting such a huge thread with huge pics, I can take them down if you want me to. 

thanks a million guys, I'll probably be posting a few other quirks if I don't find them in other threads that is.  And thank you mr RG for such a wonderful revised effect!