Hamlet Delay Help

[Caramel Kebab]

Hi everybody,

This is the 4th pedal that I've built and I need some advice. It is a Hamlet Delay on Perfboard. Currently it is making a kinda reverb-esque sound and not delaying. Could this be the PT2399? I tried grounding all the pins on PT2399 by connecting them to ground on my breadboard and that didn't seem to do anything. I am currently using a 2n5458 instead of a 2n5457, could this be the problem? I'm using a 20k trimmer for the bias and a trimmer for the volume control. I'm also using a TC1044SCPA which is why pin 1 is connected to pin 8. I'm not really sure why it isn't working, it is still passing a signal. Here are some photos as well.

Thanks for all your help.

[midwayfair]

Check the orientation of your 5V regulator. The big ones with heat sinks are usually backwards from the ones in TL-92 packaging. Google the datasheet for the part you ordered and compare whether the "output" pin for it (given in the datasheet) is connected to the PT2399 (using the continuity setting on your multimeter).

After you verify that, take voltages on all pins of the chips and transistors (but especially the PT2399, FET, and regulator) and post them here.

The only thing a 5258 will do is offer less output from the delay line, as long as you bias it correctly. (It will be harder to bias.)

It will also help if you tell us which layout you used and link to it.

[Caramel Kebab]

Hi Jon,

Here are the voltages. I roughly biased the 2n5458 to read 9v. I checked the continuity of the regulator to the PT2399 and it was connected. I don't think this matters but I am running it using a battery on my breadboard. Both pin 7 and 8 of the PT2399 were very erratic in their readings, they were roughly around .6v but it was hard to tell. I am using the layout by Effects Layout.  http://effectslayouts.blogspot.com.au/2015/12/jon-pattons-hamlet-delay.html

PT2399

Pin 1: 4.79V
Pin 2: 2.34V
Pin 3: 0V
Pin 4: 0V
Pin 5: 2.83V
Pin 6: 2.35V
Pin 7: .6v
Pin 8: .6v
Pin 9: 2.36V
Pin 10: 2.36V
Pin 11: 2.35V
Pin 12: 2.36V
Pin 13: 2.35V
Pin 14: 2.36V
Pin 15: 2.35V
Pin 16: 2.35V

Regulator - 7805

In: 7.47V
Ground: 0V
Out: 4.82V

2n3904

C: 10.90V
B: 1.020V
E: .400V

2n5458

G: 9.50V
S: 8.55V
D: 8.86V

TC1044S

Pin 1: 7.33V
Pin 2: 3.77V
Pin 3: 0V
Pin 4: 135.9 mV
Pin 5: .331V
Pin 6: 2.36V
Pin 7: 3.95V
Pin 8: 7.28V

[midwayfair]

pins 7 and 8 should not have the same voltage. They should actually have opposite voltages if I'm remembering correctly, like pin 8 should have 5v - pi7's voltage. Check for a short around there.

Your input voltage is low, too. What are you powering it with?

[Caramel Kebab]

I'm currently powering it with a 9v battery on my breadboard, which is probably the reason for the low input voltage. I'll check around for a short with pin 7 and 8. When it comes to it how should I bias the 2n5458? I have already roughly biased for 9v.

Thanks

[midwayfair]

I'm currently powering it with a 9v battery on my breadboard, which is probably the reason for the low input voltage. I'll check around for a short with pin 7 and 8. When it comes to it how should I bias the 2n5458? I have already roughly biased for 9v.

Thanks

9V for the FET is fine. It doesn't matter that much, but I usually settle around 12V. You're essentially setting how much gain it has. If you don't want to be able to make the delay louder than the dry signal or want to cut some noise, you can bias it higher. If you want more output or have a low-output FET, you can set it lower. It's just a basic inverting gain stage.

[Caramel Kebab]

I tried checking for a short by seeing if pin 7 and 8 were connected by using the continuity setting on my multimeter and they weren't connected. I checked the traces and the pins as well and they weren't connected to each other either. Is this the right way of checking for a short? (Sorry I know this is a dumb question, but I'm knew to this). I get a beep when I touch the probes along the traces i.e. touching pin 8 with one probe and touching the trace coming off of it. Should this be happening?

[midwayfair]

Yup, that's how to check for a short.

Did I miss which layout you used?
have you audio probed yet?

[Caramel Kebab]

I already mentioned the layout I'm using. It's the effects layout one. http://effectslayouts.blogspot.com.au/2015/12/jon-pattons-hamlet-delay.html  I don't have an audio probe. Should I make one? There isn't a connection between pin 7 and 8, but I will double check it. Also what else could be wrong with the circuit?

[midwayfair]

Are the footswitch pads actually ... you know, connected?

[Caramel Kebab]

Yes, the foot switch pads are connected, I plug them into the same bus on my breadboard. I forgot to mention that there is a kind of whining, whistling noise in the background of the delay. The characteristics of the noise changes when I adjust the delay pot from whiny to more of a whistle. The mix pot is also crackly and when I turn it down low it makes a pop sound and there is all this noise in the background. Does any of this mean anything?

[midwayfair]

I think you need to do some audio probing to figure out where the signal is getting lost.

The whistling in the delay line could be the low supply voltage. The pop sounds like something DC related but I'm not sure what might cause it. There shouldn't be any DC on the mix pot ... Actually I missed your voltages in the FET since I was looking elsewhere. There should not be any voltage on the FETvgate.

[Caramel Kebab]

Hi Jon,

Sorry I haven't replied yet, I didn't see what you said on the end. There is 9.50v on the gate of the FET, how should I get rid of this? When I audio probe the circuit do I need to have power going through it? I needed to have a break from the troubleshooting this but I hope to have it fully audio probed in the next week. Here are the FET voltages again.

2n5458

G: 9.50V
S: 8.55V
D: 8.86V

Thanks

[midwayfair]

how should I get rid of this?

You need to find out how in the world it's connecting to a voltage source, since nothing connected to the gate should have any DC on it whatsoever. Check the schematic and retrace through your layout for every component that connects to the FET.