I have a Hamlet + project that I have been having issues with for awhile and I can't seem to figure it out. The pedal creates white noise whether it is engaged or bypassed. The output is also rather quiet. I bought the board already populated but have since replaced the Q2 with a pn4302 because I cannot seem to find a 2n5457. I thought that was the issue but it is still there after this replacement. My voltages are as noted below. Any ideas where the issues could be coming from?
Pt2399
Pin 1-4.99v
Pin 2-2.50
Pin 3-0
Pin 4-0
Pin 5-2.64
Pin 6-2.45
Pin 7-1.13
Pin 8-1.18
Pin 9-2.50
Pin 10-2.51
Pin 11-2.51
Pin 12-2.50
Pin 13-2.50
Pin 14-2.50
Pin 15-2.50
Pin 16-2.50
Taptation
Pin 1-4.99
Pin 2-3.55
Pin 3-3.71
Pin 4-4.39
Pin 5-4.98
Pin 6-2.27
Pin 7-4.81
Pin 8-4.99
Pin 9-0
Pin 10-0
Pin 11-4.81
Pin 12-1.19
Pin 13-0.21
Pin 14-0
Mcp41100
Pin 1-4.99
Pin 2-0
Pin 3-0
Pin 4-0
Pin 5-2.45
Pin 6-2.45
Pin 7-0.30
Pin 8-4.99
Lt1054
Pin 1-1.12
Pin 2-5.0
Pin 3-0
Pin 4-0
Pin 5-0.14
Pin 6-2.54
Pin 7-1.41
Pin 8-9.25
Q1 - 2n5088
Pin 1-1.78
Pin 2-1.74
Pin 3-9.13
Q2 - pn4302
Pin 1-16.29
Pin 2-0.18
Pin 3-0
Q3 - bs170
Pin 1-0
Pin 2-2.24
Pin 3-0.29
Reg - 78l05
Pin 1-4.99
Pin 2-0
Pin 3-9.22
Pictures of the board.
(http://uploads.tapatalk-cdn.com/20160215/e61ed98a57a52c86ad10718619e9d74a.jpg)
Sent from my iPhone using Tapatalk
No ideas?
(a) Your PT2399's pin 7 and 8 voltages should not match. Pin7 should be closer to about 0.5V and pin 8 should be the opposite (IIRC; I don't usually have to measure pin 8). It's possible that white noise is constantly running through the chip, though, and that's dragging it down. (The voltage on those pins changes when signal runs through them.)
(b) You didn't label the pins on your transistors in a way that I can really tell which pin is which, but your JFET's voltages are wrong. You should have about 11V on the drain, 0V on the gate, and somewhere between 2V and 4V on the source (usually closer to 2V). Look up the datasheet, make sure you got the pinout right, and look for errors around there.
(c) Your 5088's voltages are impossible for an in-circuit bipolar junction transistor amplifier. The voltage drop between the base and emitter of a transistor can NEVER be less than 0.7V (the Fv of a silicon diode, which is what the base-emitter junction is). Your base and emitter are identical. This indicates a short, a missing connection, a bad transistor, or some other unusual problem.
I checked the pin out of the pn4302 and I did have it in backwards. I was able to get my hands on a 2n5457 and put it in place correctly. After getting the 2n5457 in, I took new readings of all the voltages and have noted what each pin is. Most voltages stayed the same after correcting the 2n5457. I thoroughly looked over the board for any bridged solder joints, ect and could not find anything. Getting frustrated with this one.
Q1 - 2n5088
Emitter Pin 1 -1.78
Base Pin 2-1.74
Collector Pin 3-9.13
Q2 - 2n5457
Gate-0
Source-1.46
Drain-3.76
Q3 - bs170
Drain Pin 1-0
Gate Pin 2-2.24
Source Pin 3-0.29
Pt2399
Pin 1-4.99v
Pin 2-2.50
Pin 3-0
Pin 4-0
Pin 5-2.44
Pin 6-2.45
Pin 7-1.13
Pin 8-1.18
Pin 9-2.50
Pin 10-2.51
Pin 11-2.51
Pin 12-2.50
Pin 13-2.50
Pin 14-2.50
Pin 15-2.50
Pin 16-2.50
Does your trimpot change the 2N5457's drain?
Use your multimeter to find out if you have continuity between the pins of the 5088. Remove it if you have to and take voltages where the pins would be. If there's no continuity between those pins and the voltages/connections aren't the same according to your multimeter (not your eyes), then the transistor might be bad.
I will check the trim pot and 5457 this evening.
I replaced the 5088 prior to taking the readings because I suspected it being bad. So unless my replacement was bad as well....?
If they were both from the same source, that might potentially make both 5088's bad, although that's pretty rare. More often you'd have a bad jfet, and from the same source you could have both be bad.
Sometimes it's very hard to find bad solder joints. I recommend that you consider using some isopropyl alcohol and an old toothbrush to clean the solder side of the board carefully. Also consider that sometimes you'll get solder bridges on the part side of the board too, so inspect those joints carefully also.
This circuit isn't going to be deadly quiet no matter what, but it is designed to be clean delay. If you're getting white noise you should be able to find where the noise is starting using an audio probe. If you need some help with how to do that, please let us know.
Jacob
Ok I checked the voltage of the 2n5457 drain as I turned the trim pot and it went as follows...
Trim pot all the way down = 1.66
Trim pot all the way up = 17.84
I did noticed the voltage would slowly drop then finally settle in.
I probed around with an audio probe and found the following....
The noise was on Q1 2n5088 collector
It was found on the Q2 2n5457 drain
It was found on Q3 bs170 gate
The noise is actually more than white noise, It has a slight squeal to it. I noticed as I turned the trim pot the sound changed pitch. All the way up created a really high squeal in the white noise/hiss.
Well that's interesting. Perhaps you have a bad cap in your power filtering section? Maybe check those?
Jacob
Your biggest problem is still that your emitter and base voltages on Q1 are the same. Regardless of what else MIGHT be wrong in the circuit, that is impossible for a working bipolar junction transistor and the cause must be located and solved.
Should I just replace the q1 again and see if that fixes the voltage discrepancy?
Sent from my iPhone using Tapatalk
Quote from: Dawnofzion on February 29, 2016, 09:20:04 PM
Should I just replace the q1 again and see if that fixes the voltage discrepancy?
Sent from my iPhone using Tapatalk
Pull out Q1. Measure the voltages. Are they the same? Then there's a problem that has nothing to do with the transistor itself. Is the base reading some high voltage and the emitter at 0V? Then go ahead and replace the transistor and see if it helps.
Heck, breadboard the Q1 stuff and measure what you EXPECT the transistor's voltages to be, then drop it onto the PCB and see if they're the same! It's only 4 parts -- the transistor, a 4.7K, a 4.7M, and a 1K.
Ok I pulled the Q1 2n5088 and measured the voltages.
With the Q1 pulled I measured the pcb holes where it was supposed to go...
Collector - 18.55
Base - 3.7
Emitter - 0
I then installed a brand new 2n5088 and immediately remeasured and got the following....
Collector - 10.55
Base - 1.63
Emitter - 1.59
Not sure what is going on.....
Any ideas?
Did you try putting the same value components (from the same bag) on a breadboard? You need to systematically eliminate all variables, including the PCB. Q1 is only a couple parts, you should be able to breadboard it in seconds.
Ok I had some time this weekend to try and diagnose this pedal a bit. One thing I found was for some reason the R2 was installed as a 3.9M and not the correct 4.7M. Do you think this might be the issue?
Unfortunately I did not have a spare 4.7M laying around, so I won't know if this is the culprit until I can get one.
Sent from my iPhone using Tapatalk
If one part is an incorrect value, there is potential for there to be more.
R2 forms a part of the input stage, and could potentially give you a low input volume. It's likely the cause of the voltage inconsistencies Jon had been pointing out.
Fix that and start over with the troubleshooting if you still feel it's off.
Jacob
Quote from: jkokura on March 14, 2016, 06:33:09 PM
If one part is an incorrect value, there is potential for there to be more.
R2 forms a part of the input stage, and could potentially give you a low input volume. It's likely the cause of the voltage inconsistencies Jon had been pointing out.
Fix that and start over with the troubleshooting if you still feel it's off.
Jacob
The 3.9M would drop the collector voltage slightly by raising the base voltage. The difference is minimal, but I'd have to see on my breadboard exactly how big a difference it would be.
This is embarrassing, but: I don't actually have a Hamlet in the house because "mine" is with a friend. So if someone else can measure their Q1 or get to a breadboard before I can, I'd appreciate a measurement on Q1's base in a working unit. (His collector and emitter are essentially correct.)
Funny story - I'm in the same boat!
Jacob
Ok got a new 4.7m resistor and installed it this evening. Same thing with the noise. I also noticed a faint high pitched squeal coming from the board when power is hooked up. I haven noticed it before, so I'm not sure if it was or wasn't doing it before. I checked voltages on the 2n5088...
E- 18.43
B- 0.87
C- 0
Sent from my iPhone using Tapatalk
Well, I thought I would resurrect this thread. I continued to have issues with the pedal and gave up on it. About a week ago I bought new parts to rebuild, including a new pcb. The only thing I reused was jacks, LEDs, foot switch and pots. I took my time to ensure I rebuilt correctly. I got everything built....put back together and decide to test it out.
I was unpleasantly surprised that it was making the exact same noise as before. I have gone through diagnostics again and I am at a loss. You would think a new pcb with all new components would fix the issue!!
I did notice a strange issue with the tempo LEDs. When I first plug in power, both LEDs flash as they should. However, one of the LEDs only flashes about 3-4 times and then it just fades out and doesn't flash anymore. Almost like the power fades out to that one LED? Not sure what would cause that?
I am so frustrated with this pedal...I'm ready to trash it all or pay to ship it to someone who can fix the dang thing.
Does the LED flash a few times every time you plug it in, or just once and then never again?
It flashes right when I plug it in. But it doesn't flash again for a while after being powered. Almost like it takes an hour or so for "stored" power to fade and allow it to flash again.
Sent from my iPhone using Tapatalk
What are you powering it with?
A 9v 'one spot' power supply direct into the delay.
Sent from my iPhone using Tapatalk
Can you give us some links as to the parts you're using? Perhaps there's an issue with the parts you've chosen, like the transistors, or the PT2399, and knowing your source on these parts might help us track down this issue.
Also, if you could film a good video and post it to Youtube and then link it to here, so that we can hear what you're hearing, that would be very helpful too.
Jacob
All my parts came from Mammoth with just a few coming from Mouser. I have tried two different pt2399's.
I will try and get a video uploaded.
Do you have a test rig so you can disconnect the stomp? If the first board was already populated and the same thing is happening with this one, and you populated it. Also, if you have a different power source like a 9volt, give that a go as well. I wonder if the 1 spot isn't the source? Also, would the color of D5 have anything to do with it? Builds that I've seen that have an LED coming off of the PT2399, the LED is always a diffused green color.
I did try a 9v battery setup and it did the same thing.
I don't have a test rig.
Sent from my iPhone using Tapatalk
Quote from: Dawnofzion on August 27, 2016, 08:48:33 PM
All my parts came from Mammoth with just a few coming from Mouser. I have tried two different pt2399's.
I will try and get a video uploaded.
What I mean is, I'd like to see the exact parts you ordered. I know that Mammoth has all the parts, but you have choices on things like your jFets, and your PT2399. I don't know if that's the issue, but perhaps you're using the wrong part in a particular spot.
If you used a 9V battery and it's making noise, then at least that's one thing off the list. Generally when you have a noisy circuit it can be traced to a bad power issue, a grounding issue, or a bad part/faulty solder join.
To be honest with you, considering it's happened to you twice with two complete builds, I can't say for certain but I suspect it has something to do with the particular setup you have. I will admit that I'm not above making mistakes, and perhaps there's an issue on the PCB, but considering that many people have built this circuit without the issue you're experiencing and you're not using a new batch of PCBs that might have a manufacturers defect of some sort, I don't think it's the PCB design itself.
So, if you can, please take measurements and give us some photos, and if you can point out the specific locations you got your PT2399's, your jFets, and any other transistors that might help steer us towards helping you.
Jacob
Picture of the board. I will get a video shortly.
(http://uploads.tapatalk-cdn.com/20160828/2b1eaae43fe5c34d1ab401a9fe970f9d.jpg)
(http://uploads.tapatalk-cdn.com/20160828/43f00481bd7b9048c9525bf4f7c3ccb9.jpg)
(http://uploads.tapatalk-cdn.com/20160828/6d97e1e7474d024d7911db4e5886ad38.jpg)
(http://uploads.tapatalk-cdn.com/20160828/f66d8cfd3f6cdde6cf04519d18cc7a37.jpg)
Sent from my iPhone using Tapatalk
Since you used sockets, it'd possible to verify the "analog" portion of the PT circuit separately from the tap tempo stuff. In other words, you can temporarily replace the digipot's connection to pin6 with a simple potentiometer (and pull the TAPLFO chip).
I won't be able to help much with the tap tempo stuff.
Quick video showing how the second tempo LED fades out after powering up.
https://youtu.be/7oMDdzMLJUk (https://youtu.be/7oMDdzMLJUk)
Second video showing the noise/hiss I'm referring to.
https://youtu.be/vHaEhrDnSkY (https://youtu.be/vHaEhrDnSkY)
Jeez ... I've never heard anything like that come from a pedal period much less a PT2399.
If you pull the pt entirely does it go away?
I took the PT out and the noise was still there. It's changed in sound slightly with the PT removed but was just as loud. You could actually hear a faint 'tick' with the blink of the one LED that works.
Okay, so here are some thoughts...
- If the noise is coming from the circuit, you won't be able to tell if the pedal is off, because it's not a true bypass effect
- I think the LED issue has to be related to the Taptation. You mentioned getting all new parts, but not whether you got a new taptation set. If your Taptation chip is not functioning correctly, that would account for that issue.
- The noise could be related to the chips in your circuit, but we haven't gotten specifics on the transistors you're using - specifically the 2N5457 is the important one, because that's the most likely culprit if you're getting noise related to a faulty or fake part. JFets are occasionally faked these days.
- Because this circuit uses many semi-conductors, pretty much any of them could be the culprit. However, because you're using a whole new set, I'd suspect that it's actually more likely to be the Taptation, rather than these parts.
Jacob
I did buy a new taptation set with the other parts. The pots and jacks are the only thing I reused.
The parts that are installed....
2n5457 http://www.mammothelectronics.com/2N5457-p/100-1029.htm (http://www.mammothelectronics.com/2N5457-p/100-1029.htm)
2n5088 http://www.mammothelectronics.com/2N5088-p/100-1000.htm (http://www.mammothelectronics.com/2N5088-p/100-1000.htm)
BS170 http://www.mammothelectronics.com/BS170-p/100-1016.htm (http://www.mammothelectronics.com/BS170-p/100-1016.htm)
LM78L05 http://www.mammothelectronics.com/LM78L05ACZ-p/400-1108.htm (http://www.mammothelectronics.com/LM78L05ACZ-p/400-1108.htm)
LT1054 http://www.mouser.com/ProductDetail/Texas-Instruments/LT1054IP/?qs=sGAEpiMZZMuo%252bmZx5g6tFDbWjHMXK2vq (http://www.mouser.com/ProductDetail/Texas-Instruments/LT1054IP/?qs=sGAEpiMZZMuo%252bmZx5g6tFDbWjHMXK2vq)
Okay, this is how I'm going to recommend you proceed. You need to systematically eliminate potential sources of the noise.
Pull EVERY IC in the circuit.
This includes the charge pump. You'll still be able to run the circuit without it.
Put the effect in bypass for good measure.
Is the noise still there?
If it is, pull Q2. Is the noise still there? (If it is, then I'll try to work out what could be wrong in a separate post.)
If it's not there while Q2 is in the circuit, we're going to rebuild the circuit one IC at a time.
Put the charge pump back in. Did the noise return?
Next, put the PT2399 back in and put the noise pot at its highest resistance (= least noise). You'll need a time "pot". Just grab a 10K resistor and put it in the socket holes for pins 4 and 5 of IC3. Is the noise there? (You'll have to flip the bypass, presumably.)
If it isn't, then all that remains are the tap tempo assembly chips. Unfortunately, they have to be tested together. If the noise is gone until these go back on the PCB, though, then you've tracked down the issue to a relatively small section of the board.
My advice for testing those is to breadboard the tap tempo part of the circuit, and identify if the chips are working: you will be able to verify that the LEDs work, and once you get the tappy bit working on the breadboard, you can connect pins 5/6 to the pin 6 connection on the main PCB with a wire from your breadboard.
If the noise returns only when the chips are connected from your breadboard, or if they malfunction before being connected to the PCB, then either there is a bad component involved or perhaps a mismarked resistor.
If the noise is NOT there when you connect it from your breadboard, then the problem lies on the circuitboard components for the tap tempo -- again either a bad or perhaps mismarked part, or a bad solder joint, or a rare circuit board error (which I want to stress would be extremely rare to happen to two PCBs).
Ok, I pulled ALL the IC's (including the taptation set). Noise was still there. I then pulled the Q2...noise was still there. The noise changed pitch (lower) when the Q2 was removed but it was still there in volume.
You've plugged your guitar directly in to your amp just to check if the noise is gone?
Sent from my iPhone using Tapatalk
Quote from: jimilee on August 30, 2016, 02:36:38 AM
You've plugged your guitar directly in to your amp just to check if the noise is gone?
Sent from my iPhone using Tapatalk
Yep. I did in the video above.
Noise without all the ICs and Q2?
That is immensely confusing. There is nothing active in the circuit at that point.
Did you pull out Q3 and/or Q1?
Q3 is only there to add modulation for the delay, and Q1 is your input gain station.
Based on this, I think Jon might have more ideas than I, but I would expect your power is suspect personally. Especially considering that this has happened twice with completely different boards with completely different parts.
Can you run the test again with a 9V battery? A battery is a clean power source that should not be creating noise?
Jacob
Quote from: jkokura on August 30, 2016, 04:44:01 AM
That is immensely confusing. There is nothing active in the circuit at that point.
There is. Q1.
If we go back to page 1, we can see that the voltages on Q1 have been odd since the first build.
I'm unaware of a problem that manifests itself as that sort of sound, though. I think op would have noticed if the one spot was bad, and it's unlikely that the power supply components (caps etc) are bad on both builds -- and there's plenty of redundancy even if a specific batch of capacitors were bad. A backwards transistor would have resulted in a completely different problem (oscillation in the PT), and a bad transistor at worst simply wouldn't amplify.
I know it doesn't make things better, but I can understand your frustration with a complicated build where the designers aren't able to positively identify the issue even with all the information you've given us. I hate being stumped with ways to help
almost as much as you hate not having a working pedal.
Definitely try the 9V -- I wouldn't try to run the digital chips with it, but at least it can help troubleshoot Q1.
Also, I'm again going to suggest breadboarding the Q1 assembly on your breadboard. I don't remember seeing that you ever confirmed you did this, but at this point either (a) the components are bad or (b) there's something wrong on the circuitboard or (c) there's something wrong with the power supply or maybe test rig. You either have to eliminate components from the circuitboard (which you've done as far as you can go) or eliminate the circuitboard, and a breadboard is the only way to do that. You only need the Q1 components: The input cap, the 4M7, the 4K7, the 1K, and the output cap. Once it's hooked up on the breadboard, run your guitar through it and, assuming the components are good, you should have a quiet 4.7x gain stage. (If the noise is there, then you can suspect the power supply or the parts.)
You can power it one of two ways: You can simply put the 4K7 to the power rail, OR you can run a wire from the collector of your breadboarded transistor to the collector spot on the PCB. Your goal is to make connections one at a time for Q1 -- thus substituting the handful of components at each connection on the PCB with those on your breadboard -- until the noise comes back and you are thus able to pinpoint its source.
Ok. I hooked the pedal back up with a 9v (same battery used last time) and got the same noise.....then I decided to try a different battery for good measure and I was pleasantly surprised when I heard silence. I guess it was power all along....but who would have thought a battery would do the same thing? And why does one battery do it and the other doesn't? Either way I think I have found the problem with the sound.
However, The second tempo LED is still not working, And when I turned the amp way up I heard a tick with the one tempo LED that is working. I added a resistor to both tempo LEDs and almost all the tick went away. But I'm still at a loss for why the second tempo LED fades out the way it does.
Any ideas on the LED issue? Still a new taptation kit so I wouldn't think both would do the same thing. I guess I could try a different led and see what happens?
Thanks for all the help on this thing.
You might have to put a thread in the digital forum on DIYstompboxes to get adequate help on the LED issue. It's Aron's chip/project and someone on that forum did the programming. It could conceivably be a known issue.
I definitely find it weird that a battery would cause the same noise as when you powered it with a one spot. Do you have any other power adapters, another one spot, or other types of batteries? It would suck to have to power this monster with a specific battery! You'd only get maybe an hour per shot!
It's possible too that there's an issue in the power section. It is very strange that you'd get this twice in a row, but I would once again double and triple check your soldering, your part values, your part orientation, and even use something to scratch between the individual solder pads. If you can use some rubbing alcohol to clean the back of the board, that might be worth doing as well.
Jacob
I dug around in my box of random guitar things and found a couple different power supplies. Both were 9v - 400ma. I thought I would hook them up and check for the same noise.
The pedal made noise with all 3 power supples. Each one made a different noise. All at the same volume, just with a different tone.
It's Crazy how this thing makes so much noise with any power supply, and attached but not with a battery.
It does look like it's a power section issue.
A battery has no switching noise for a start. I don't know if all the power supplies are switched mode but it's fairly likely. If they're all making noise even with the charge pump pulled then you'll have to start poking around the components in the power section.
First, a little explanation. The filter capacitors in a DC supply are primarily to filter out a very high-pitched noise that switching supplies make (basically the frequency of the switching). They're not for filtering hum in that case and they could actually be lower values than we tend to use and still do their job. In some other types of power supplies, the capacitors are there to hold a reserve of voltage in between the power supply swings every 120Hz (because rectified 60Hz AC is doubled). When filtering high frequencies, the internal resistance of the power supply and the capacitors form an RC filter.
IIRC, as the filtering improves, the pitch goes up.
So you've got a *fairly* low-pitched noise, which I suppose could indicate a filtering issue.
I'm going to try to simplify some things here while we search for the issue.
1) Remove the Zener. If you're never at risk for plugging in anything except a 9V supply, this isn't needed. Plus when they fail they can cause all sorts of issues, like shorting your power supply to ground. Sometimes they also cause noises. Etc.
2) If the 5V regulator is socketed, try removing it. This will leave the charge pump and the transistors as the only things running. (We've already established that the circuit can run with the charge pump. You can leave that in or remove it as you like.)
3) Check your caps. I know you probably already did this, but check to be sure.
4) I just noticed a typo in Jacob's schematic, where C18, the main filter capacitor, is only 10uF. There are actually a lot of power supplies where this would be fine (remember how I said above that we're just filtering very high switching noise?), but it was a 100uF in my original design. Go ahead and increase that. Maybe this should be #1 on this list, but I'd still remove the Zener.
I will try changing out the 10uf cap for the 100uf first. The two additional power supplies that I tried out did produce a really pitched low noise....much lower than the 1spot. So what you said above makes sense.
In regards to the zener....if it is ok to remove it, what was its purpose? Can it remain out?
Also, could you share a link to a proper zener for this project? I used one I had laying around and if I purchase another one, I want to make sure I am getting something that is appropriate. You can see in my images it is the small red one. Maybe this is the wrong Zener?
I am away from Home for a couple days but will try the 100uF cap exchange when I get back.
A 12V Zener is there to prevent more than 12V from hitting the LT1054, because that would blow the chip and it's more expensive than the Zener. Essentially, this part is just insurance, but if you're sure you're only feeding the pedal 9V, than removing it should be fine.
If you're just using a random Zener, it's possible that's the issue. I don't know for sure, because I don't know the part you're using.
Here's the option from Mouser that I recommend.
http://ca.mouser.com/ProductDetail/Fairchild-Semiconductor/1N4742A/?qs=sGAEpiMZZMtQ8nqTKtFS%2fD313Kx94AdFJGMlPg6CdPg%3d (http://ca.mouser.com/ProductDetail/Fairchild-Semiconductor/1N4742A/?qs=sGAEpiMZZMtQ8nqTKtFS%2fD313Kx94AdFJGMlPg6CdPg%3d)
Here's one from Smaller that I recommend,
http://smallbear-electronics.mybigcommerce.com/diode-zener-1n4742a/ (http://smallbear-electronics.mybigcommerce.com/diode-zener-1n4742a/)
Jacob
I removed the Zener and replaced the 10uf with a 100uf as discussed. Still have a noise. I then replaced the d4 for safe measure....still noise. After each thing done above I checked and the noise would change pitch. I did notice the pitch changes as I rotate the bias pot.
Still dead quiet with a battery.
Have you tried using the 5088 on a breadboard to see if that's the issue?
Jacob
I don't have a bread board. I need to get one.
I am picking up a breadboard today....however, I have never used one. I know is may be an elementary question, but I am still kind of new to pedal building. How would I go about building the power section of the pedal on the bread board to try and find the problem?
Quote from: Dawnofzion on September 07, 2016, 04:06:32 PM
I am picking up a breadboard today....however, I have never used one. I know is may be an elementary question, but I am still kind of new to pedal building. How would I go about building the power section of the pedal on the bread board to try and find the problem?
A breadboard will have two rails, one for ground (-) and one for the positive voltage. Most breadboards have two sets of rails, one on each side. Since the whole row on one side will be connected, make sure you keep the +9V rail separate from the +18V rail. Alternatively, if you have a road rage board, you can use that for your +18V connection point. (I keep one around for breadboarding.)
As far as basic breadboarding goes, Smallbear has a series with some basic tips starting here:
http://diy.smallbearelec.com/HowTos/Breadboarding/BreadboardIntro.htm
I know it's kind of a pain to run through some stuff unrelated to your project, but the tutorial really is great and it's way more thorough than what I can type out in a forum post.
Unfortunately, his tutorial for ICs involves an in-line 8-pin op amp. To get you started there, you want to have the IC "straddle" the center division of the breadboard, so that each pin has its own separate column.
Start simple -- get the basic power section stuff and a single transistor stage working first, to make sure you've grasped how the breadboard works. Keep your multimeter handy so you can check continuity.
Breadboarding is a fun way to mod effects and it's also a good way to eliminate some frustrations while troubleshooting, so it's worth some extra time up front to develop some good habits.
Just to echo what Jon is talking about, the real key issue here is isolating that Q1 transistor. It seems to me that we need to verify that it can work without causing you any noise. If the source of the noise is that transistor, we can simply swap it out for one that's working properly.
If it's not the issue, and we know that it will work without making noise, then we know that it's another issue. It's part of the reason we recommend testing PCBs before installing them into an enclosure (rock before box) so that we know it's not the PCB, and can check through switch and wiring system to find the problem if it doesn't work when boxed.
Eliminating and verifying independant sections is the key to debugging.
Jacob
I picked up a few different LEDs when I got my breadboard. This evening I thought I would replace the tempo LEDs to see what that would do. To my surprise the new LEDs worked just fine. Both flashing as they should. However, it is still making some really crazy noises. Check out the video below.
https://youtu.be/FK5Vlzr73d8 (https://youtu.be/FK5Vlzr73d8)
On another note, I have read through some basic bread boarding instructions. After watching a couple of bread boarding how-to's on YouTube, I thought I was ready to do the power section of this pedal...
I pulled the schematics out and immediately was overwhelmed. Haha.
I guess I was a tad overconfident. Then I thought, even if I knew how to lay out the power section on the breadboard....how do I connect it to the PCB and where? This is how I would check for the noise. Correct?
The way I would do it is to pull the charge pump from the PCB and insert a wire from the 18V output from the breadboarded supply at the pin8 connection on the PCB. You'll lose a quarter of a volt from the extra 1N5817, but that's not that big of a deal. Or you can solder a wire to one of the 18V points (i.e., on the trimpot or on the top of the 4k7 connecting to Q1).
You might have an easier time breadboarding the charge pump section if you use the Road Rage schematic. There's a lot less going on in that!
Ok I finally got the noise gone. I bought a new power supply in combination with replacing a couple power section parts and the noise is gone. I boxed it up into the enclosure and now I only get the dry signal. Zero delay coming through. If I turn the repeats all the way up I get oscillation sounds but no delay sound from the guitar. It's as if the pedal is bypassed at all times? It was working perfectly prior to boxing it up into the enclosure.
I thoroughly checked everything over and cannot see anything that looks suspicious.
Any ideas?
Sent from my iPhone using Tapatalk
Quote from: Dawnofzion on October 02, 2016, 08:37:30 PM
Ok I finally got the noise gone. I bought a new power supply in combination with replacing a couple power section parts and the noise is gone. I boxed it up into the enclosure and now I only get the dry signal. Zero delay coming through. If I turn the repeats all the way up I get oscillation sounds but no delay sound from the guitar. It's as if the pedal is bypassed at all times? It was working perfectly prior to boxing it up into the enclosure.
I thoroughly checked everything over and cannot see anything that looks suspicious.
Any ideas?
Sent from my iPhone using Tapatalk
Backs of the pots isolated? If you unbolt the pots and pull the board up, does it come back? Basically, try one by one pulling things away from the enclosure until the sound comes back. Just to narrow down the problem.
I took everything out of the enclosure and I get the same thing. It has to be a short somewhere right?
Sent from my iPhone using Tapatalk
It's also possible that it's a cold or loose solder joint due to the stress induced when you fix them to the enclosure.
I'd check the delay pot connection and the associate parts. Using an audio probe you should be able to listen to the input of the PT2399 and see if signal is hitting that point, and then if it is, you can check the output and trace to the Mix area.
Jacob
I'm with Jon. Sounds like a short on the back of the pots or a cold solder. If you don't isolate the back of the pots (double side tape or dust seals) you WILL have trouble.
I use these, and they work a treat: http://smallbear-electronics.mybigcommerce.com/dust-cover-for-16mm-alpha-pots/
I put two layers of electrical tape on the back of my pots to isolate them.
I checked the Delay pot connection and all was good. I checked for solder bridges and resoldered any connection that looked suspect. Same thing...
I need to try the audio probe as Jacob mentioned above.
Sent from my iPhone using Tapatalk
Hi...R2 forms a part of the input stage, and could potentially give you a low input volume. It's likely the cause of the voltage inconsistencies Jon had been pointing out.Fix that and start over with the troubleshooting if you still feel it's off.
pcb assembly (http://www.7pcb.co.uk/PCB-Assembly/)