Hamlet+ problems

[Dawnofzion]

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.


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[jkokura]

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

[midwayfair]

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.)

[jkokura]

Funny story - I'm in the same boat!

Jacob

[Dawnofzion]

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




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[Dawnofzion]

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.

[somnif]

Does the LED flash a few times every time you plug it in, or just once and then never again?

[Dawnofzion]

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. 


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[midwayfair]

What are you powering it with?

[Dawnofzion]

A 9v 'one spot' power supply direct into the delay.


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[jkokura]

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

[Dawnofzion]

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.

[jimilee]

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.

[Dawnofzion]

I did try a 9v battery setup and it did the same thing.

I don't have a test rig.


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[jkokura]

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