Neo vibe voltages "again"

Zedmin_fx · March 25, 2008, 08:37:16 PM

Ok guys I took the voltages I have a ggg pcb and their schem no mods or subs were done. Do you think I need to replace the transistors again I bought double last time just incase I should have two.

Q1. C 2.7 Q7. C 11.9 Q13. C 19.7

E 1.6 E 4.4 E 3.1

B 1.2 B 5.0 B 3.8

Q2. C 5.4 Q8. C 15.6

E 2.1 E 4.9

B 2.7 B 4.8

Q3. C 8.0 Q9. C 11.9

E 4.9 E 4.3
B 5.4 B 4.9

Q4. C 15.6 Q10. C 15.6

E 5.0 E 6.1

B 4.9 B 5.9

Q5. C 11.9 Q11. C 24.2

E 4.3 E 6.4

B 4.9 B 3.7

Q6. C 15.6 Q12. C 24.2

E 5.0 E 5.3

B 4.8 B 6.4

dxm1 · March 25, 2008, 10:12:58 PM

Are you sure that you've labelled those measurements correctly? Q1-Q10 are NPN transistors set up as amplifiers, so C>B>E. That is, the collector should be a higher voltage than the base, and the base higher than the emitter.

mdh · March 26, 2008, 01:50:18 AM

Quote from: dxm1 on March 25, 2008, 10:12:58 PM
Are you sure that you've labelled those measurements correctly? Q1-Q10 are NPN transistors set up as amplifiers, so C>B>E. That is, the collector should be a higher voltage than the base, and the base higher than the emitter.

I suspect that his meter is probably pulling the base voltages down when he measures them, at least for Qs 1, 4, 6, 8 & 10. That's been known to happen with this circuit. Zedmin_fx, this would be the time to measure the voltage directly across the B-E junction for any of the transistors for which the emitter voltage appears to be higher than the base voltage. Be sure to pay attention to where you place the test probes. In this case, black should go on the emitter, and red on the base. If you get a positive reading in the neighborhood of 0.5 to 0.7 V, then those are probably fine, and there's no need to report those voltages in detail (if you wanna say, "Hey guys, I checked the suspect B-E voltages, and they're fine," cool).

Can you remind us of exactly how the pedal behaves? My recollection is that it's not vibing, and the bulb is on steadily. Can you confirm that? Is it otherwise OK, i.e., does it pass signal with little to no distortion? If that's the case, then we should be concentrating on the LFO. Hopefully a more trained pair of eyes will pass over this thread and be able to interpret the voltages on Q11 & Q12. In the meantime, I would suggest that you take a close look at the wiring of the speed and depth pots -- sometimes offboard wiring errors can kill LFOs. Also if you could remind us what transistors you're using for Q11 and Q12.

Zedmin_fx · March 26, 2008, 10:12:28 AM

Quote from: dxm1 on March 25, 2008, 10:12:58 PM
Are you sure that you've labelled those measurements correctly? Q1-Q10 are NPN transistors set up as amplifiers, so C>B>E. That is, the collector should be a higher voltage than the base, and the base higher than the emitter.

Yea I am 100% sure the only thing I didnt do is c>b>e I did C>e>b. Do you thing I should just replace the transistors?

Zedmin_fx · March 26, 2008, 10:16:59 AM

Quote from: mdh on March 26, 2008, 01:50:18 AM
Quote from: dxm1 on March 25, 2008, 10:12:58 PM
Are you sure that you've labelled those measurements correctly? Q1-Q10 are NPN transistors set up as amplifiers, so C>B>E. That is, the collector should be a higher voltage than the base, and the base higher than the emitter.

I suspect that his meter is probably pulling the base voltages down when he measures them, at least for Qs 1, 4, 6, 8 & 10. That's been known to happen with this circuit. Zedmin_fx, this would be the time to measure the voltage directly across the B-E junction for any of the transistors for which the emitter voltage appears to be higher than the base voltage. Be sure to pay attention to where you place the test probes. In this case, black should go on the emitter, and red on the base. If you get a positive reading in the neighborhood of 0.5 to 0.7 V, then those are probably fine, and there's no need to report those voltages in detail (if you wanna say, "Hey guys, I checked the suspect B-E voltages, and they're fine," cool).

Can you remind us of exactly how the pedal behaves? My recollection is that it's not vibing, and the bulb is on steadily. Can you confirm that? Is it otherwise OK, i.e., does it pass signal with little to no distortion? If that's the case, then we should be concentrating on the LFO. Hopefully a more trained pair of eyes will pass over this thread and be able to interpret the voltages on Q11 & Q12. In the meantime, I would suggest that you take a close look at the wiring of the speed and depth pots -- sometimes offboard wiring errors can kill LFOs. Also if you could remind us what transistors you're using for Q11 and Q12.

Ok when I blew this thing up it all it would do it light up however the lamp was very very dim. I replaced the voltage regulator and the diode bridge. Now when I plug my pedal in the lamp lights but wont pulse however its brighter. Just like it was befor I blew it up and didnt work. I remember what we did was put in new transistors and it worked is that what I should do now?

mdh · March 26, 2008, 03:02:39 PM

I just went and reread your previous thread. The reason that replacing the transistors worked the first time was that the pinouts were apparently wrong. Just the same, I suppose it's possible that Q11 or Q12 got damaged back when you had power supply problems. Anyway, it seems like what you want to do is replace those transistors, so go for it. I frankly don't know how to interpret those voltages. Don't mess with Q1-Q10 for now, as they don't have anything to do with the LFO. Also, I reiterate my suggestion to check for problems with the wiring of the speed and depth pots.

Zedmin_fx · March 26, 2008, 04:42:17 PM

Ok I replaced all Of the transistors. I put sockets in place for a few of the crappy areas ie q 11 12 13still my lamp wont light up argg I am so sick of this I just want a working pedal here. I Really dont think that the wires are my trouble here I have been thou them like 10 times I will get my voltages again later tonight. You guys want the voltage reading like this Q1. C 5.3

B 5.3

e 5.3
I guess I will aslo go thought the wires just to say i did. Are there anything you might also need me to look at? I just want a uni-vibe

Zedmin_fx · March 26, 2008, 04:46:52 PM

I mean The lamp wont pulse has anyone else had this problem what all did they do?

mdh · March 26, 2008, 08:15:24 PM

Quote from: Zedmin_fx on March 26, 2008, 04:42:17 PM
OI guess I will aslo go thought the wires just to say i did.

Dude, to be quite honest, this kind of attitude may be why you haven't been getting a whole lot of help, especially from the more well-informed folks around here. I've been trying to do my best to help you, but if you're going to follow instructions given in good faith "just to say I did," then we're not going to get anywhere. You've got to understand that the people trying to help you here are kind of working blind -- we can't make measurements on your board directly, so we have to rely on you to try the things we ask you to do. If we ask you to do something and you ignore us, but keep pleading for help... well, what's the point?

Take a look at the schematic here: http://www.geofex.com/FX_images/vibeschm.pdf. Can you tell us the voltage you read at the point where R39 and R40 meet? It's the point with the little yellow box reading 11.7V on the schematic. Could you also tell us whether turning the lamp driver trimmer affects the brightness of the bulb? Finally, with the circuit off, could you measure the resistances between points E & D and between points D & C with the speed pot turned fully counterclockwise, fully clockwise, and set to the middle position? Could you do the same for points G & H and H & F with the depth pot CCW, CW and in the middle?

Zedmin_fx · March 26, 2008, 10:05:20 PM

yea I am sorry man I was in a bad mood and I have been thu the wires so many times its so exasperating. So right now I will go check the wires, tomorrow I will get voltages and stuff for you. Also I feel kinda dumb Beckie it worked and then I blew it up hmm o well.

Zedmin_fx · March 27, 2008, 10:07:00 AM

Hey MDH its time to party!!!!! I fixed it and it now works I checked the wires and I found a little small wire jumper shorting out the speed pot. I took it out and viola it was pulsing!!!!! Its sounds really good so far I frigging love it. I was palying with it at 11:30 last night. I have yet to try it on a loud amp bc my mom is home during the mornings. THANK YOU SO VERY MUCH TO ALL WHOM HAVE HELPED ME OUT !!!!!!!. I have learned a great deal with this project. THANKS AGAIN YOUR ALL THE BEST

CHRISTIAN

mdh · March 27, 2008, 09:03:51 PM

Congratulations! Get that baby boxed up and protected from the elements! Just be sure not to make the same mistake as last time with the power supply.

Zedmin_fx · March 27, 2008, 09:30:28 PM

Quote from: mdh on March 27, 2008, 09:03:51 PM
Congratulations! Get that baby boxed up and protected from the elements! Just be sure not to make the same mistake as last time with the power supply.

Hey man My univibe has been 100% done since 8 this morning and I have jammed on it in all of my free time I love it. It makes a lot of noise ( is that from a small mini amp and my not so great tv speaker or the pedal itself). Now my pedal box is all beat up from drilling and moving it so much 9its been like 4 months). Again I want to say sorry for sounding stupid the other day I more meant that I would go thu the wires to put that on my check list of things I have done. AND THANK YOU THANK YOU THANK YOU FOR ALL OF YOUR HELP.

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Neo vibe voltages "again"