So I assembled my first Mad Beans board and it went well...BUT...for some reason when i turn the gain knob up to about 1 o'clock and beyond it stutters and doesn't stop. It sounds like somethings shorting it out and causing a stuttering sound of full volume to no volume, full volume no volume.... This happens when you get to about 1 o'clock turning clockwise.
I took it back apart and checked all my joints. I reassembled it and made sure nothing was touching. After doing this the problem continued. What should I check next? Any ideas what the problem might be?
I should specify that I used the A1M for the gain pot.
check to see that the pot isn't faulty, first off.
after that, i would use audio probe to see where the fault first arises. so check after each gain stage, after the clipping stage and after the filter stage.
also check that your supply voltage is stable (ie battery isn't dieing, 9v adapter isn't acting funny).
Crap...I guess I have to order parts to build a probe now.
You most likely have what you need to build one.
http://diy-fever.com/misc/audio-probe/
A couple things could help us help you...
IC voltages and transistor voltages, plus pics are helpful
I don't believe your problem is in the gain pot. It's being used as a variable resistor in this circuit. When you turn the pot clockwise it is limiting the current flowing back into the negative feedback loop of the IC. By restricting the signal here it creates more gain out of pin 1 of IC1A. The IC is being used as a differential amplifier. Wiki it for some "throne" reading.
You may have a resistor value mix up somewhere? A little more info will help.
Josh
If the cap for the probe wasn't 63V I'd have it all.
I used this IC:
http://www.mammothelectronics.com/TL082CP-JFET-Op-Amp-p/400-1117.htm
and these transistors:
http://www.mammothelectronics.com/2N7000-N-Channel-60-V-D-S-MOSFET-p/100-1043.htm
When you ask for the voltages are you saying I need to messure the voltage they're pulling?
I'll post pics when I get home. I'm at the lowest level of noob there is so thanx for bearing with me.
I just double checked all the resistors. They all seem to be correct but I am confused with the value of the R1 resistor. R1 is supposed to be a 1M. What I have in it's place is coded Brown, Black, ?, Yellow, Brown. I can't tell the color of the third stripe.
Here are pictures of both sides of the board.
(http://i980.photobucket.com/albums/ae285/guyskankrye/IMG_3817.jpg)
(http://i980.photobucket.com/albums/ae285/guyskankrye/IMG_3819.jpg)
You don't need a 63v rated cap, anything rated 18v or above is fine.
For the voltage measurements: Put your DMM on the V setting. Place the black probe on the power jack ground and then touch a pin on the IC with the red probe. Record the voltages for each of the 8 pins. Do the same for each transistor leg.
For IC pins and transistors utilize the data sheets. The first two are free ;) Google is your friend for datasheet locating.
http://www.datasheetcatalog.org/datasheet2/6/0ed6f5j6u9r503itwtq3d7f38cky.pdf
http://www.fairchildsemi.com/ds/2N/2N7000.pdf
R1 is fine. It's a bit strange because it's a 1.08M but it's fine.
Also verify that your getting 9v from your power source. Do this prior to anything else.
Josh
Can't tell from the pic. Is D1 backwards?
Jacob
Quote from: gtr2 on April 04, 2011, 10:41:43 PM
You don't need a 63v rated cap, anything rated 18v or above is fine.
For the voltage measurements: Put your DMM on the V setting. Place the black probe on the power jack ground and then touch a pin on the IC with the red probe. Record the voltages for each of the 8 pins. Do the same for each transistor leg.
For IC pins and transistors utilize the data sheets. The first two are free ;) Google is your friend for datasheet locating.
http://www.datasheetcatalog.org/datasheet2/6/0ed6f5j6u9r503itwtq3d7f38cky.pdf
http://www.fairchildsemi.com/ds/2N/2N7000.pdf
R1 is fine. It's a bit strange because it's a 1.08M but it's fine.
Also verify that your getting 9v from your power source. Do this prior to anything else.
Josh
Again, showing my noobness, I'll have to pick up a multimeter tomorrow. I only have an old radio shack cheapo with a needle. I'm using a Voodo Lab Pedal Power Plus that's powering everything else well so I assume it would be fine.
Once I get the readings from the IC and transistors and compare them to the datasheets what do I do if they differ? I guess we'll cross that road when we get there...
Quote from: jkokura on April 04, 2011, 10:59:09 PM
Can't tell from the pic. Is D1 backwards?
Jacob
D1 is installed correctly.
I'll rephrase it, make sure you are getting 9v to the board. Measure with the red probe on the 9v pad and the black on GND. You probably are but it's always good to check.
Second, I agree with Jacob. It looks like the polarity of D1 is wrong. The diode band should be orientated like the silkscreen on the pcb. To me it looks like the orange/red band is facing the opposite direction.
Josh
Quote from: gtr2 on April 05, 2011, 11:08:47 AMSecond, I agree with Jacob. It looks like the polarity of D1 is wrong. The diode band should be orientated like the silkscreen on the pcb. To me it looks like the orange/red band is facing the opposite direction.
I think the picture is a little deceiving (or maybe I'm the one that's deceived). I believe it's in there correctly. I used this diode: http://www.mammothelectronics.com/PhotoGallery.asp?ProductCode=120%2D1017 (http://www.mammothelectronics.com/PhotoGallery.asp?ProductCode=120%2D1017) From my understanding the BLACK band is what needed to be lined up with the silkscreen on the PCB. Was I wrong? There is a close-up of how I have it installed below.
Thanx for all the help guys. Having such a helpful and welcoming community is a real blessing.
(http://i980.photobucket.com/albums/ae285/guyskankrye/IMG_3820.jpg)
Ok, D1 looks correct in that pic.
Checked the boards voltage and it's getting 9.26V.
The IC's readings were:
1 - 4.44V
2 - 4.44V
3 - 4.24V
4 - .1mV (sometimes dropped to 0)
5 - 4.44V
6 - 4.44V
7 - 4.44V
8 - 8.86V
The transistors readings were:
Q1
D - 4.42V
G - 4.44V
S - 4.44V
Q2
D - 4.44V
G - 4.44V
S - 4.44V
What do I need to compare these numbers to on the datasheets?
I don't know exactly what the voltages are but these seem about right. Pin 4 is the ground pin so it should register around 0
You need your audio probe to pin point where you're having the issue.
Josh
Everything to me is pointing to either a bad IC, a bad diode, or a bad pot. Because it's only your gain pot that's doing this, it has to be in the parts between the pot and the IC, so C2 and C3, and R4 and R5, and the pot and IC of course.
Have you tried a new pot? Have you tried a new IC?
Jacob
Quote from: jkokura on April 05, 2011, 10:58:42 PM
Everything to me is pointing to either a bad IC, a bad diode, or a bad pot. Because it's only your gain pot that's doing this, it has to be in the parts between the pot and the IC, so C2 and C3, and R4 and R5, and the pot and IC of course.
Have you tried a new pot? Have you tried a new IC?
Jacob
I built my probe and tested everything. The pot seemed fine. I got signal on each side of C2, C3, and R5. On R4, on the other hand, there was only signal on one side. Is that the culprit?
No R4 goes to ground. That's how it should work.
Bad pot, or IC is still what I'm thinking. Have you got a spare dual op amp?
Jacob
I probed the IC and pin #4 gave no signal (ground right?) also pin #8 gave a VERY weak signal.
Pin four is ground, and pin 8 is 9V in. Threre souls be sound on the power rail.
It's good that you're probing, but do you have another IC to try? That may be the problem.
Jacob
Quote from: jkokura on April 06, 2011, 02:12:44 AM
Pin four is ground, and pin 8 is 9V in. Threre souls be sound on the power rail.
It's good that you're probing, but do you have another IC to try? That may be the problem.
Jacob
The only other IC I have right now is a LM1458.
Just to be sure I put the meter on the 1 and 3 lugs of the pot. It measured .894M from 0 to 10. I put it on the 1 and 2 lugs and it was at 1.2 ohm at 0 and .891M at 10. The pot's good right? I detached it from the board.
EDIT: I found a TLC2272 and put it in there and it continued to do the same thing.
Quote from: tenwatt on April 06, 2011, 02:18:59 AMThe only other IC I have right now is a LM1458.
Just to be sure I put the meter on the 1 and 3 lugs of the pot. It measured .894M from 0 to 10. I put it on the 1 and 2 lugs and it was at 1.2 ohm at 0 and .891M at 10. The pot's good right? I detached it from the board.
EDIT: I found a TLC2272 and put it in there and it continued to do the same thing.
So are those readings good on the pot? If so...what should I check next?
Hey man, sorry I didn't get back.
Yes, it sounds like your Pot is fine.
I'm perplexed. I've never heard this phenomenon, nor have I any idea what the problem could be considering everything I would expect it to be checks out to be fine.
Here's what I propose you do now. Make the circuit do the strange noise by turning the gain pot up. Use your audio probe to trace backwards through the circuit from the output. When you get no strange noise, work forward until you do get strange noise. Whatever part is in between is where your problem is.
Keep your schematic handy, and cross parts off the list that don't seem to be the problem. If it's not in the gain structure element of the pot, it's got to be somewhere afterwards. Because the trannies and diode clipping seems to be fine also, it's probably after that also. If this is still acting up, you might need to take a break from it, because sometimes you just need to walk away for a bit.
Jacob
Thanx for the feedback. I'll be on it as soon as I get home. Go figure...my very first build results in an unknown phenom. ::)
I really am grateful for everyone's time and help.
Okay, I started probing on the "In" of the board.
R1 was good on one side, ground on the other.
C1 was good on both sides.
R2 was good on both sides.
R3 was good on one side....but the other side produced the stutter.
Did I find the problem?
Obviously it's a part of the problem, but which side of R3? One side connects to the ic input, and the other to VB, so which side?
Jacob
Quote from: jkokura on April 06, 2011, 10:50:42 PM
Obviously it's a part of the problem, but which side of R3? One side connects to the ic input, and the other to VB, so which side?
Jacob
I believe it's the pad connected to VB. If you're looking at the board it's the bottom lug just above the ground.
Yeah, that's the one. That means that the problem could be with your power supply, or with any of the parts connected to your power rail. Have you checked your power supply yet? What your ground? If you power is leaking to ground in a very small amount I would bet that would cause some crazy symptoms...
What I don't get is why it only happens when you turn up your gain pot!
Jacob
Quote from: jkokura on April 06, 2011, 11:53:55 PM
Yeah, that's the one. That means that the problem could be with your power supply, or with any of the parts connected to your power rail. Have you checked your power supply yet? What your ground? If you power is leaking to ground in a very small amount I would bet that would cause some crazy symptoms...
What I don't get is why it only happens when you turn up your gain pot!
Jacob
The ground reads 0mV and the "9V" reads 9.25V. What's the "power rail"?
That's the connection between your parts and power. Since R3 connects to the parts connected to your 9V, it will likely now be that the problem rests in the parts connected to your power supply.
Two things. Try a different power supply - a battery is best. Also, take a look at the schematic and carefully looking at the parts connected to your power. There's some electrolytic caps, some resistors and a diode in there. Check them out.
One more think I thought of, maybe disconnect the LED if you've got it connected...
Jacob
LED removed and the problem persist.
I'm using a Vodoo Lab Pedal Power 2 that's working well with everything else.
So you're saying test anything connected to the power...is that the "VB"? What do you mean by "carefully look at"? Probe? Multimeter? Visually inspect solder?
All of the above.
Yes, try another power supply, battery preferred.
If you look at the schematic, there is a series of parts between the 9V and VB pads. All those parts are what I'm talking about.
Have faith, it will work eventually.
Jacob
R12, when probed, makes no sound on either side. It read 9.25V on both sides.
That's the current limiting resistor for the LED. That's correct, so any other parts?
Jacob
R13 - stutters - 9.25V to 8.85V
D2 - stutters - 8.85V to ground
C9 - stutters - 8.85V to ground
C11 - stutters - 8.85V to ground
R14 - stutters - 8.85V on one side but goes crazy and gives no reading on the other - measures 9.91k across the resistor
R15 and C10 also stutter and give no reading on the meter.
I'll keep going but I'm hoping R14 is the problem.
K, you should have about 9v on one side of R14, and half that in the other side.
You have located a part of the issue.
Jacob
Quote from: jkokura on April 07, 2011, 02:00:16 AM
K, you should have about 9v on one side of R14, and half that in the other side.
You have located a part of the issue.
Jacob
Crap...just part? I'll replace R14 what should I do after that?
Check all your voltages, and see if the problem goes away. I bet theres nothing wrong with the part, rather the somehow there is a solder bridge or other small problem like that. It's just that voltage indicates a problem. By the way, you shouldn't audio probe on you power rail, sorry for indicating you can. You should just use your DMM there.
Jacob
Quote from: jkokura on April 07, 2011, 02:19:27 AMBy the way, you shouldn't audio probe on you power rail, sorry for indicating you can. You should just use your DMM there.
Have I potintially caused more problems by doing so?
Rather than just jumping in and desoldering it I tried scraping around the pads with a pick to make sure there were no bridges. I cleaned it really well on both sides and retested it and there was still no change. I'm going to pick up a desoldering iron and another 10k from Radio Shack today and give it a shot.
I desoldered R14, cleaned the PCB really well, and installed a new resistor...no change.
What's next?
K, so you should be getting about 9 volt on one side of R14, and you should be getting approximately 4.5 volts on the other side. The side towards the 9V in is the side that should have 9V. I can't tell you more than what I've already told you I don't think. You need to search for what is causing that to not be true (I think). I can't think of another reason why this would be occurring, and unless someone else can pipe up and give us any other ideas, you need to keep searching all the parts for a part that might be incorrect, or backwards, or faulty, or just plain not soldered correctly.
One thing I can think of is your IC socket. Is it possible that some things are connecting where they shouldn't there? Try taking your IC out, then seeing if there's continuity between any of the socket terminals. If the schematic says there should be, then that's ok, but if there's continuity where there shouldn't be then fix that.
Jacob
Out of curiosity I pulled the IC out of the socket and measure R14 and everything was fine. Socket?
Well, I'm completely put out. It's to far above my head to figure it out. I was so excited to take on building pedals but I already feel exhausted.
Thanx for all your time and help.
Quote from: tenwatt on April 07, 2011, 10:22:40 PM
Out of curiosity I pulled the IC out of the socket and measure R14 and everything was fine. Socket?
Did you measure R14's value or did you measure the voltage?
If the voltage is fine, that indicates to me that either there is something wrong with the socket, or it's a problem with the IC. If you've measured the value, you can't rely on your measurement if the part is still in the board. As long as the bands are correct, you don't need to worry about it much.
Sorry man, it's tough sometimes. I've had many things go wrong with my builds, and it can be very frustrating indeed. You might just need to take a break for a few days or even a week or so. If worst comes to worst, I'll get it working for you if you send me the board.
Jacob
Quote from: jkokura on April 08, 2011, 03:28:54 AM
Quote from: tenwatt on April 07, 2011, 10:22:40 PM
Out of curiosity I pulled the IC out of the socket and measure R14 and everything was fine. Socket?
Did you measure R14's value or did you measure the voltage?
If the voltage is fine, that indicates to me that either there is something wrong with the socket, or it's a problem with the IC. If you've measured the value, you can't rely on your measurement if the part is still in the board. As long as the bands are correct, you don't need to worry about it much.
Sorry man, it's tough sometimes. I've had many things go wrong with my builds, and it can be very frustrating indeed. You might just need to take a break for a few days or even a week or so. If worst comes to worst, I'll get it working for you if you send me the board.
Jacob
I measured the voltage. Couldn't it also be something on the other side of the IC? If I remove the IC and R14 voltage wasn't funky it could be anything from the IC or behind it? Tonight I'm going to take voltage readings on EVERYTHING with and without the IC.
Here are all the readings:
R1 - 1.6mV/0mV
R2 - 4.26V/4.26V
R3 - 4.46V/4.26V
R4 - .1mV/.1mV
R5 - 4.46mV/4.46mV
R6 - 4.46mV/4.46mV
R7 - 4.46mV/4.46mV
R8 - .1mV/.1mV
R9 - 2.1mV/2.6mV
R10 - 1.3mV/1.3mV
R11 - 1.2mV/1.2mV
R12 - 9.25V/9.25V
R13 - 9.25V/8.85V
R14 - 8.85V/4.46V
R15 - 4.46V/.1mV
C1 - 4.26V/.3mV
C2 - 4.46V/4.46V
C3 - 4.46V/.3mV
C4 - 4.46V/4.46V
C5 - 4.46V/4.46V
C6 - 4.46V/.2mV
C7 - 4.46V/.8mV
C8 - .6mV/.1mV
C9 - 8.85V/.1mV
C10 - 4.46V/.1mV
C9 - 8.85V/.1mV
D1 - 4.46V/4.46V
D2 - 8.85V/.2mV
Q1 - 4.46V/4.46V/4.46V
Q1 - 4.46V/4.46V/4.46V
IC:
1 - 4.44V
2 - 4.44V
3 - 4.24V
4 - .1mV
5 - 4.44V
6 - 4.44V
7 - 4.44V
8 - 8.86V
Everything looks right as far as voltages. Pretty much what I would expect.
R1 and R9 looks suspect on the build but I'm having trouble reading the values. Can you list the band colors for those two? I can't see them clearly. They should be a 1M and 150k, resp.
Quote from: madbean on April 09, 2011, 02:22:22 AM
Everything looks right as far as voltages. Pretty much what I would expect.
R1 and R9 looks suspect on the build but I'm having trouble reading the values. Can you list the band colors for those two? I can't see them clearly. They should be a 1M and 150k, resp.
R9 is pretty clearly Brown, Green, Black Orange, Brown (150k)
R1 that is weird. I can't tell what the third band is. It's obviously Brown, Black, ?, Yellow, Brown. The "?" isn't clear. It's not black, like the band above it. It seems to be silver or grey.
Try measuring R1 in circuit with your DMM. We are just looking for ballpark, not an exact value.
On my color band calculator that silver band gave R1 a 1.08M value as listed previously in the post. I do remember it coming up with some unconventional value warning though :D
Josh
Quote from: madbean on April 09, 2011, 04:52:15 AM
Try measuring R1 in circuit with your DMM. We are just looking for ballpark, not an exact value.
1.009M
I wouldn't think that would cause your problem anyways, its just a pull down resistor.
Any other ideas? I feel a lack of confidence to start another project until I figure out what I screwed up on my first.
Quote from: gtr2 on April 09, 2011, 05:03:38 PM
I wouldn't think that would cause your problem anyways, its just a pull down resistor.
If it were defective or somehow a very very low value it could alter the input impedance of the op-amp which could lead to oscillation with enough gain (I'm guessing).
Quote from: tenwatt on April 09, 2011, 05:08:36 PM
Any other ideas? I feel a lack of confidence to start another project until I figure out what I screwed up on my first.
Have you tired using a smaller value for the gain pot? Say, 500k...audio or linear.
Quote from: madbean on April 09, 2011, 08:05:40 PM
Quote from: tenwatt on April 09, 2011, 05:08:36 PM
Any other ideas? I feel a lack of confidence to start another project until I figure out what I screwed up on my first.
Have you tired using a smaller value for the gain pot? Say, 500k...audio or linear.
Nope...thought about it but didn't do it. I have a A500k. I'll try it tomorrow.
Another shot in the dark is that it could be the 2n7000s have a different pinout than normal. Can you tell who is the manufacturer? There should be some markings on the faces of those transistors.
Quote from: madbean on April 10, 2011, 03:12:57 AM
Another shot in the dark is that it could be the 2n7000s have a different pinout than normal. Can you tell who is the manufacturer? There should be some markings on the faces of those transistors.
I put the A500k in and there was no change in the problem. It's weird because the pedal sounds GREAT until the gain hits about one o'clock then it starts spitting ans stuttering.
Here's a pic of the transistor:
(http://i980.photobucket.com/albums/ae285/guyskankrye/IMG_3821.jpg)
Quote from: tenwatt on April 09, 2011, 05:08:36 PM
Any other ideas? I feel a lack of confidence to start another project until I figure out what I screwed up on my first.
I urge you not to give up. If you can't get this one going, I think you should get another one. Maybe something simplier to give you some more building confidence. I flopped up on my second build and I spent 6-8 months trying to figure out what was wrong. Never solved it and it almost caused me to quit altogether. I'm glad I didn't cause that was the only build I screwed up so far. If you plan on building more than one pedal this is what is gonna help you understand how they work. Plus you can always come back to this build when you have more experience and knowledge.
Well, I can't really read the markings on the transistors, so I can't say much there.
I wonder if the long pins you've used to connect the pots might have lifted some solder pads through downward pressure. Phew, this is kind of a tough one!
The markings made me think STI, but I couldn't find any details by googling. Not a symbol I recognize. If might be worth spinning them, but I'm also aware that flipping mosfets as clipping diodes doesn't seem to make a difference in some circumstances, so pinout shouldn't matter - right?!?
Yes this is a tough one. Immensely discouraging. I keep encouraging to leave this for a while and do something else for a while. Come back to it, and then start over. Sometimes what really needs to happen is to start over on something fresh. I've said it before, but only ONE board has ever defeated me. Some things was wrong with the traces, and that was a hand etched board. New board with the same components and it worked fine. I don't think thats' the case here, because the board is manufactured and the voltages seem pretty much correct.
One thing I've noticed a couple times is that your ground doesn't actually read 0 volts. It's sometimes only 1mv, but that's still not how ground should be acting. Perhaps as you turn the pot up and down somehow voltage is leaking to ground? The fact that it's oscillating may also indicated that something is going in cycles, which has to be driven by the IC or by a transistor, still pointing to a faulty IC for me.
Here's what I suggest. A couple shots you've give us has shown the board in an enclosure. I assume that you've got it hooked up to a switch and stuff, so I suggest that you pull the board out of the enclosure and eliminate the switch (you may already have). Just hook up the pots and the DC, and use a battery if you haven't been already. I know your power supply is a good one, but a battery just plain eliminates the powersupply from being the issue at all (It's good practice to use a battery to test ALL your pedals first).
If it works outside of the enclosure then we're one step closer. If it doesn't, it's easier to trouble shoot it outside of the enclosure.
Jacob
Those trannies look like this (http://www.st.com/stonline/books/pdf/docs/10202.pdf) to me.
Possible.
Jacob
Just a suggestion, but i notice you havn't used a socket for your transistors. Maybe you fried them a bit when soldering them in?
Not according to the voltages.
Jacob
Hey tenner...I can hook you up with another Ego board if you want to give it another go. You've tried really hard on this one, and you should be rewarded with a working pedal, after all. If you feel up to it, let me know.
Quote from: madbean on April 13, 2011, 12:50:48 AM
Hey tenner...I can hook you up with another Ego board if you want to give it another go. You've tried really hard on this one, and you should be rewarded with a working pedal, after all. If you feel up to it, let me know.
Wow! Thanx! I'll likely take you up on that. I built Jacob's testing rig last night and first made sure I was getting 9V out of the rig. I was getting 9.25V so that was good. I then desoldered my board from the switch and ran some new leads from the "IN", "GND", "9V, and "OUT" pads. Hooked it up to the testing rig...nothing. Put my DMM on the 9V pad and got 9.25V. Tested R12....nothing. Measured the resistance of R12 and got pretty close to 4.7k. I'll sit down and measure everything on the board tonight...this thing's not going to beat me.
*EDIT* The Egodriver has a "SW" pad for the switch. Would that have to be hooked up to the testing rig to test it properly? Currently, I didn't hook it up. I just thought of that.
The SW pad is for the LED. Basically, what happens there is that R12 works as a current limiting resistor for your LED indicator. It helps to have that CLR mounted on the board so you don't have to have one free floating in your enclosure. You only need the SW to connect to your switch to turn the LED on and off. R12 is not in the circuit at all, it's just for the LED.
What's interesting is that you have power at the 9V in pad on your PCB, but not after that. What's it like at R13? You should have 9.25v at the side closest to the 9V in pad, and a little bit less than that on the other side. It may be that there is a problem that has arisen because of the unsoldering process.
Jacob
Quote from: jkokura on April 13, 2011, 05:43:17 PMWhat's it like at R13? You should have 9.25v at the side closest to the 9V in pad, and a little bit less than that on the other side.
I'll check as soon as I'm home. I can't remember off the top of my head. I know that I measured a LOT of the componants and the majority was going haywire.
Quote from: jkokura on April 13, 2011, 05:43:17 PMIt may be that there is a problem that has arisen because of the unsoldering process..
That's kinda what I'm afriad of. Everything
looks clean with no burns or anything but that was my first time desoldering a board. Shoot, it was only my second time to solder a board so the odds that I screwed up aren't to slim.
Yeah....R13 is dead as a doornail. Here are some pics so you can see I didn't fry it:
(http://i980.photobucket.com/albums/ae285/guyskankrye/IMG_3826.jpg)
(http://i980.photobucket.com/albums/ae285/guyskankrye/IMG_3825.jpg)
Any other ideas?
Ok, You should be getting the same voltage at the 9V in pad, and the pads for R12 and R13 that connect straight to the 9V in pad. If you're not, then you need to either resolder the pads or change a resistor out. Sorry Jeremy, that's all that there is at this point. You have to be getting voltage past R13 for anything to work. If you take a look at the schematic, you'll see that R13 is inline with the 9V in pad on it's way to powering everything else.
Jacob
I redid the IN, OUT, 9V, and GND connections and it's working again. Here are the current readings:
R1 - 0mV/0mV
R2 - 4.26V/4.26V
R3 - 4.46V/4.26V
R4 - 0mV/0mV
R5 - 4.46V/4.46V
R6 - 4.46V/4.46V
R7 - 4.46V/4.46V
R8 - 0mV/0mV
R9 - 4.46V/4.46V
R10 - .7mV/.7mV
R11 - .6mV/.6mV
R12 - 9.25V/9.25V
R13 - 9.25V/8.85V
R14 - 8.85V/4.46V
R15 - 4.46V/0mV
C1 - 4.26V/0mV
C2 - 4.46V/4.46V
C3 - 4.26V/0mV
C4 - 4.46V/4.46V
C5 - 4.46V/4.46V
C6 - 4.46V/0mV
C7 - 4.46V/0mV
C8 - .3mV/0mV
C9 - 8.85V/0mV
C10 - 4.46V/0mV
C11 - 8.85V/0mV
D1 - 4.46V/4.46V
D2 - 8.85V/0mV
Q1 - 4.46V/4.46V/4.46V
Q1 - 4.46V/4.46V/4.46V
IC:
1 - 4.46V
2 - 4.46V
3 - 4.26V
4 - 0mV
5 - 4.46V
6 - 4.46V
7 - 4.46V
8 - 8.85V
VOL:
1 - 0mV
2 - .2mV
3 - .2mV
TONE:
1 - 0
2 - 0
3 - 0
GAIN:
1 - 4.31V
2 - 4.46V
3 - 4.46V
HP/LP:
.3mV/.3mV
Thanx again for helping so much and dealing with my ignorance.
So I don't how the voltages I put in the last post (one above this one) look compared to what they should be but I assume that the ones with low or no voltage are potintial problems?
The voltages that usually matter for us are the IC and Tranny voltages usually. The voltages on the caps and resistors can sometimes help, but an Audio probe becomes more helpful then. And frankly, your IC and transistor voltages look fine. You've got ground where you're supposed to, and the voltages look like they're dividing properly.
So now, if your pot is still acting weird, I have no idea why. i hate that. It shouldn't be doing what you say it's doing. It is still doing the strange noise right?
Jacob
Quote from: jkokura on April 14, 2011, 03:55:13 PM
The voltages that usually matter for us are the IC and Tranny voltages usually. The voltages on the caps and resistors can sometimes help, but an Audio probe becomes more helpful then. And frankly, your IC and transistor voltages look fine. You've got ground where you're supposed to, and the voltages look like they're dividing properly.
So now, if your pot is still acting weird, I have no idea why. i hate that. It shouldn't be doing what you say it's doing. It is still doing the strange noise right?
Jacob
Yup...still making the noise. Where should I start probing and what should I NOT probe?
Take your schematic, and the layout, and start to follow the audio path from input to output. You should start at the input wire to the board, and then move part through part, making notes on your schematic. Also, you don't need to check any part of the ground or power connections For example:
Input: sound is great
R1: sound is great
C1 in: Sound is great
C1 out: sound is now muffled
R2 in: Same as C1 out
R2 out: Even more muffled
Etc. Make those notes, but don't post them here. What you're looking for is where the strange sound starts for you. What you're trying to do is locate the beginning of the strange sound. Once you've located it, you can do a couple things - tell us about what you've found and ask for more help, change or resolder parts and see if you can deal with it yourself, or take Bean up and get a new board and start over.
Hope this helps Jeremy!
Jacob
Will do. Thanx!
I'm sorry if this has been annoying but I've tried to just take it as a learning experience. That's why I haven't just caved and accepted Brian's offer yet. I really want to learn what I'm doing as opposed to just following directions. I really do value all the info I've receive so far.
If you really give in you could try sending it to someone else to give a go at it!
Quote from: tenwatt on April 14, 2011, 06:24:22 PM
Will do. Thanx!
I'm sorry if this has been annoying but I've tried to just take it as a learning experience. That's why I haven't just caved and accepted Brian's offer yet. I really want to learn what I'm doing as opposed to just following directions. I really do value all the info I've receive so far.
Not annoying. Frustrating yes, because it hasn't been an easy fix. Everything I would normally say you should do hasn't worked. I don't know why it's doing what you're saying. We'll get it working I'm sure, but it might take a new board for you to get a good product in your hands.
Jacob
Tonight I desoldered and rewired all the pots to insure that I hadn't screwed up some wires. I then probed it all and the ONLY places I got a sound with out strobing was on the top side of R3 and on the third pin of the IC.