Hamlet+ problems

[Dawnofzion]

Picture of the board.  I will get a video shortly. 








Sent from my iPhone using Tapatalk

[midwayfair]

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.

[Dawnofzion]

Quick video showing how the second tempo LED fades out after powering up.

https://youtu.be/7oMDdzMLJUk




Second video showing the noise/hiss I'm referring to.

https://youtu.be/vHaEhrDnSkY

[midwayfair]

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?

[Dawnofzion]

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.

[jkokura]

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

[Dawnofzion]

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

2n5088   http://www.mammothelectronics.com/2N5088-p/100-1000.htm

BS170     http://www.mammothelectronics.com/BS170-p/100-1016.htm

LM78L05  http://www.mammothelectronics.com/LM78L05ACZ-p/400-1108.htm

LT1054        http://www.mouser.com/ProductDetail/Texas-Instruments/LT1054IP/?qs=sGAEpiMZZMuo%252bmZx5g6tFDbWjHMXK2vq

[midwayfair]

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).

[Dawnofzion]

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.

[jimilee]

You've plugged your guitar directly in to your amp just to check if the noise is gone?


Sent from my iPhone using Tapatalk

[Dawnofzion]

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.

[jkokura]

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

[midwayfair]

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.

[Dawnofzion]

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. 

[midwayfair]

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!