Another beginner question. What causes input voltage to be pulled down?

[jimmybjj]

I have a tonepad phase 90 that worked well at one point. i was trying different mods and put it away for a couple of days. I come back today and put it back to stock config, now i can't get it to work. I would give all my voltage so you guys could help me debug but they would mean anything because input voltage it off. The input voltage before load is 8.97v and loaded by the circuit it is pulled down to 4.0v What causes this and what should i look out for? I can't find any solder bridges, but that doesn't mean aren't any. Is this the most likely culprit? Any help would be very appreciated.

[jimmybjj]

Would posting my "low" voltages be helpful in determining the source of the problem? Could one trace the source of the problem by reading the voltages relative to each other despite all of them being low?

[petemoore]

 The only advice for such a 'special' case is wait until someone say go on the 1/2~ voltage measurements.
  Such a voltage drop is obviously a bug, and the battery probably won't last long with such a load on it.
  The other obvious thing is that something is loading the supply.
  I wouldn't mind to take a look at the voltages at the divider [two equal value resistors strung between V+ and Gnd. make 1/2v where they meet.
  It could something touching that shouldn't, this would also throw a resistance reading out of whack. 
 

[R.G.]

I have a ... that worked well at one point. i was trying different mods and put it away for a couple of days. I come back today and put it back to stock config, now i can't get it to work... What causes this ...the most likely culprit?

I'm sorry. I don't mean this personally. It's just that we get this message in one form or another so often. I do understand the spirit of adventure that leads people to head off into the unknown.

However, if you (anyone, not just you personally) are going to go off ripping parts out and "improving" something, you need to either (a) put in the time to understand what you're doing well enough to get back, or (b) understand and accept ahead of time that it may never work again. At least leave yourself a trail of bread crumbs (notes, pictures, something) to lead yourself back to known territory.

What causes this is going off modding and not understanding what you're doing. The simplest thing to do is to cut every single component off the board, lift out the stubs, and put in new parts, trying to notice if you damaged the PCB along the way.

Again I apologize. It's not you personally. But it would save so many people so much trouble if they would not try to mod what they don't understand at least a little. Mother Nature does not award extra points for being bold.  Sometimes the dragon wins.

[jimmybjj]

I have a ... that worked well at one point. i was trying different mods and put it away for a couple of days. I come back today and put it back to stock config, now i can't get it to work... What causes this ...the most likely culprit?

I'm sorry. I don't mean this personally. It's just that we get this message in one form or another so often. I do understand the spirit of adventure that leads people to head off into the unknown.

However, if you (anyone, not just you personally) are going to go off ripping parts out and "improving" something, you need to either (a) put in the time to understand what you're doing well enough to get back, or (b) understand and accept ahead of time that it may never work again. At least leave yourself a trail of bread crumbs (notes, pictures, something) to lead yourself back to known territory.

What causes this is going off modding and not understanding what you're doing. The simplest thing to do is to cut every single component off the board, lift out the stubs, and put in new parts, trying to notice if you damaged the PCB along the way.

Again I apologize. It's not you personally. But it would save so many people so much trouble if they would not try to mod what they don't understand at least a little. Mother Nature does not award extra points for being bold.  Sometimes the dragon wins.

No need for apologize   I understand what your trying to say. That being said I disagree. With all due respect (because i have observed your knowledge and experience) I think your response is kind of closed minded. If everyone followed this kind of thinking the only people that could be apart of the diy community would be electrical engineers, is this the type of response that should be given every time someone tries something new without full understanding? It's not like i said "Here is a picture, tell me what i did wrong" My question was presented in a way so that I could learn more "What causes this to happen?" I am truly trying to learn and understand. Playing outside of our comfort zones leads to new discovery and fast track learning, if everyone played within the limits, we wouldn't learn much, always waiting on someone else to figure things out for you. While I agree modding and not understanding what your doing might lead to it never working again, modding and not understanding leads to understanding though experience, and more importantly might stop the heavy influx of newbie questions that would occur if I had to rely on someone else to tell me what to do. I am fully aware this circuit may never working again but that's part of the diy experience, I'll just start over tomorrow   Again, I say these things with all due respect and I apologize if I offended you in any way. Thank you for all pf the knowledge and experience that you share with community.

The only advice for such a 'special' case is wait until someone say go on the 1/2~ voltage measurements.
 Such a voltage drop is obviously a bug, and the battery probably won't last long with such a load on it.
 The other obvious thing is that something is loading the supply.
 I wouldn't mind to take a look at the voltages at the divider [two equal value resistors strung between V+ and Gnd. make 1/2v where they meet.
 It could something touching that shouldn't, this would also throw a resistance reading out of whack.  
 

I'll post some voltages tonight, if anyone is still willing to help me  

[petemoore]

  Tha's a danker. Danish patience is needed, be prepared for flooding !
  Once the flood hits...whether your stuff is still good is a good question.
  Pretty much a large sorting process to find 'that' thing which isn't in other texts.
  Big fan of texts myself, stuck with no references...
  The dogmatic approach...maybe not rip every piece off the board [ie start with new board instead?
  With intui-lect, [intillectual/intuition] just behind the forehead [proper installation usually requires some programming and study, experience], measure every resistor:
  When 'anamolous-low' resistance is read, look for another current path through the circuit or lift one end [after triple checking the color code.
  Measure every 'common' [connection. Clip the black DMM lead 'here', read schematic and make sure it goes 'where' [according to diagram], and not 'there' [anywhere else it shouldn't be]...skip the red DMM around the board contacts [lift power supply first], investigate every 'beeping' node.
  Taking voltages everywhere...why not...perhaps a large voltage drop or other clue would pop up.
  Lifting components [ughh]...there are quite a few on that board [ughh to the power of 42], sad to say, but this sounds [so far] very similar to 'the battery gets hot'...finding the stray ground, a tough one...often not so bad say 'lead-touches-box'' syndrome...other times it's a batch of patches...1 of which is shorting...could be any one of these.
  Try to imagine you did sprinkle peas, backtrace your mod steps and use a close-in light [and magnifying glass] for inspecting, use DMM wherever you can apply it...
  Voltages might help [whacky though already puts 'em into uncharted territories, [perhaps a new chart can be thrown away once it helped], audio probe isn't really suggested since it's probably gonna kill audio at the input.
  Clip a DMM 'beepmoded', black lead to ground [and V+, and...anywhere seen fit], see if there's a stray ground or anything...anomolous 'jumper' that shouldn't be.

[R.G.]

No need for apologize   I understand what your trying to say. That being said I disagree. With all due respect (because i have observed your knowledge and experience) I think your response is kind of closed minded. If everyone followed this kind of thinking the only people that could be apart of the diy community would be electrical engineers, is this the type of response that should be given every time someone tries something new without full understanding? It's not like i said "Here is a picture, tell me what i did wrong" My question was presented in a way so that I could learn more "What causes this to happen?" I am truly trying to learn and understand. Playing outside of our comfort zones leads to new discovery and fast track learning, if everyone played within the limits, we wouldn't learn much, always waiting on someone else to figure things out for you. While I agree modding and not understanding what your doing might lead to it never working again, modding and not understanding leads to understanding though experience, and more importantly might stop the heavy influx of newbie questions that would occur if I had to rely on someone else to tell me what to do. I am fully aware this circuit may never working again but that's part of the diy experience, I'll just start over tomorrow   Again, I say these things with all due respect and I apologize if I offended you in any way. Thank you for all pf the knowledge and experience that you share with community.

And there is no need to apologize for your view. I did not mean it to say "never try anything until you already have the college degree", and I'm all for failing forward. I can't tell you the number of things that I've disassembled just to learn what they did inside.

I was reacting only to what you actually typed, and what other less-informed and motivated people than you would read. I would have had an entirely different response if you had originally typed:

While I agree modding and not understanding what your doing might lead to it never working again, ... but that's part of the diy experience

If you appreciate and know that, you're ready to learn. That wasn't apparent from your original note. Sure, post the voltages. I suspect that just *measuring* the pin voltages might lead  you right to the issue, but if it doesn't post them here and we'll figure it out.

[petemoore]

  Be prepared, at any time, to just walk away.
  Sometimes ''the program'', reloaded [I lose schematic memory sometimes] after other experiences such as trying something else, persueing applicable reading materials etc. will make the time spent working this thing out...less work...more play time.
  1 voltage doesn't make for a right/left or right/wrong point to be found.
  Finding often involves lifting or connecting something that makes the 1 whacky voltage suddenly become 2, right and left working.

[jimmybjj]

And there is no need to apologize for your view. I did not mean it to say "never try anything until you already have the college degree", and I'm all for failing forward. I can't tell you the number of things that I've disassembled just to learn what they did inside.

I was reacting only to what you actually typed, and what other less-informed and motivated people than you would read. I would have had an entirely different response if you had originally typed:

While I agree modding and not understanding what your doing might lead to it never working again, ... but that's part of the diy experience

If you appreciate and know that, you're ready to learn. That wasn't apparent from your original note. Sure, post the voltages. I suspect that just *measuring* the pin voltages might lead  you right to the issue, but if it doesn't post them here and we'll figure it out.

Thanks for your help R.G. and your professionalism. I don't know i might be going a little crazy because I understood half of what pete was saying, thanks pete.

Well I don't know what exactly I did(which is actually pretty aggravating) but it is working now, kinda. New problem, i have a factory mxr block logo unit and i compared it to my tonepad unit when it was working well and they sounded similar. They had differences but the depth (i think that is the word or it might be sweep) on the units was very similar. No that my tonepad is working again their is much less depth (or might be sweep) In any case i have included a link to a small mp3 so that you can hear the difference. Is there a defect in my circuit or does it just need adjusting? All transistors are match using the geofex matcher, adjusting the trim pot on the unit does not affect the depth ( sweep)

http://sites.google.com/site/foundher1234/untitled.mp3

[MoltenVoltage]

I recommend taking this journey alone.  When you get to the other side, which you will if you persevere, you will have learned a lot more than just what was wrong with this particular build.

How does that old saying go?

Give a man a pedal, he can make one type of noise, teach a man to solder and he can make every type of noise.

[Bad Chizzle]

Oh man, laughed my ass off!

Classic!

[jimmybjj]

I recommend taking this journey alone.  When you get to the other side, which you will if you persevere, you will have learned a lot more than just what was wrong with this particular build.

How does that old saying go?

Give a man a pedal, he can make one type of noise, teach a man to solder and he can make every type of noise.

I agree and subscribe to this school of thought but even people with this mentality need help  especially when their is no prior experience. I tried the depth mod, swapping the 1m resistor for a 470k and a pot (could this be called a intensity mod as well) I find that I am having a hard time using the standard descriptive terms, which makes it hard to describe to you guys. I also tried putting in a different set of matched transistors, same result. Any hints on where to go? I couldn't find any information on altering the sweep, found plenty on the Ross phaser.

[petemoore]

Oh man, laughed my ass off!

Classic!
  You mean George Ohm ?
   
  http://www.installer.com/tech/ohmslaw.html

  http://www.radioremembered.org/ohmslaw.htm

[jimmybjj]

Ok, still looking for some help. This will be the last time i bump this thread if there is no response. I am still having the same problem, the circuit works but it is not as deep (i really don't know how to describe it but I will include a soundclip) as the factory unit. I built another board (have two now) and the two tonepads sound very similar. I found one youtube (http://www.youtube.com/watch?v=YZqv5LMdp_Y&feature=youtube_gdata) clip of the tonepad and it sounds more like the one that i built rather than the factory unit, I now think it is the nature of the build rather than something wrong. That being said i would still like to modify mine to have similar depth(sweep) to the factory unit. Things I have tried; 470k resistor and pot replacing the 1m resistor (didn't affect sweep), tried 33k to replace 22k resistors in parallel with transistors (seemed to introduce distortion), replaced the 4.7k with 10k (seemed to alter the sweep but range(depth) of it). Any advice would be appreciated.

My sound clip  http://sites.google.com/site/foundher1234/untitled.mp3