Building the Echo Base PCB

[Sanguinicus]

And here's the voltages, refer to previous page for more info:

https://www.dropbox.com/s/5054d9v9my5psbc/echo%20base%20voltages.png?dl=0

Pins 7 and 8 of the right side TL072 look fishy.

Not sure how to embed Dropbox images, sorry.

From garcho's suggestion in the next post:

Left Side TL072	4066	PT2399	Right side TL072
1 - 5V	1 - 4.66V	1 - 5V	1 - 5V
2 - 5V	2 - 4.66V	2 - 2.5V	2 - 5V
3 - 4.5V	3 - -0.4mV	3 - 0.3mV	3 - 5V
4 - 0V	4 - -0.5mV	4 - 0.1mV	4 - 0.8V
5 - 5V	5 - 0.1mV	5 - 2.8V	5 - 5.5V
6 - 5V	6 - 4V	6 - 2.5V	6 - 5V
7 - 5V	7 - 0.1mV	7 - 3.8V	7 - 7.4V
8 - 8.9V	8 - 2.5V	8 - 2.1V	8 - 8.1V
	9 - 2.5V	9-16 - 2.5V
	10 - 4.66V
	11 - 4.66V
	12 - 8.7V
	13 - 8.57V
	14 - 8.95V

[garcho]

you could just post them here, by typing them in, so the people willing to help you don't have to jump around from dropbox to downloads, etc.

[slacker]

Something's wrong with the PT2399 pin 7 and 8 voltages, they should be much lower than the 3.80 and 2.1 Volts that you have. Double check the values and the connections to the capacitors attached to those pins.

For reference here are the expected voltages http://www.diystompboxes.com/smfforum/index.php?topic=60662.msg498824#msg498824

[Sanguinicus]

Something's wrong with the PT2399 pin 7 and 8 voltages, they should be much lower than the 3.80 and 2.1 Volts that you have. Double check the values and the connections to the capacitors attached to those pins.

For reference here are the expected voltages http://www.diystompboxes.com/smfforum/index.php?topic=60662.msg498824#msg498824

I'll look at this tonight. I should have bought it into work today to muck around with.

Pin 8 of the 4066 looks incorrect also.

Finding problems is good. I might have to cobble together an audio probe also.

Should also point out the state of the effect. It was turn on, tails on, clean on, LFO on, no guitar signal. That is, i was plucking a string when I was metering. But it was connected between guitar and amp.

you could just post them here, by typing them in, so the people willing to help you don't have to jump around from dropbox to downloads, etc.

Good idea. I'll edit the post so others can see.

[Sanguinicus]

It works. Here's what I did. I was inspecting the caps on pins 7 and 8 of the PT2399, the values were correct. Flipped over the board to inspect the soldering and pin 8 was not even soldered! Bloody hell.

I am a giddy goat and feel slightly embarrassed. I did say I reflowed all the solder previously. I reflowed the existing solder 

Here's a question though, is there a way to mod the time pot so when it's turned all the way down, so the time is effectively zero? The slapback effect fully CCW is cool, but I want even shorter for those waling 80's metal leads.

[bluebunny]

The datasheet suggests a minimum time of 31.3ms (with a resistance of 0.5 ohms).  Just don't allow it to power-up with a resistance this low.  Not sure how easy it would be to achieve this with the Echo Base circuit, since pin 6 isn't simply grounded via a resistor.

[duck_arse]

I have been shown a mod using a led in the E of the slow-start/anti-lock transistor to get shortest possible delay. see if you can find a copy of Cozybuilder's "archangel".

[Cozybuilder]

I have been shown a mod using a led in the E of the slow-start/anti-lock transistor to get shortest possible delay. see if you can find a copy of Cozybuilder's "archangel".

That schematic was posted in Jack Orman's rework of the Little Angel, I think the LED idea was from Jon Patton.

http://www.diystompboxes.com/smfforum/index.php?topic=106572.20

[slacker]

It works.

Excellent good to hear you got it working.

Here's a question though, is there a way to mod the time pot so when it's turned all the way down, so the time is effectively zero? The slapback effect fully CCW is cool, but I want even shorter for those waling 80's metal leads.

You shouldn't need any mods to do this, with the time pot CCW it should be into chorus or doubling sounding territory definitely shorter than what you'd normally refer to as slapback. If you give us a soundclip I can tell you if yours is acting correctly.

[Sanguinicus]

quote]
You shouldn't need any mods to do this, with the time pot CCW it should be into chorus or doubling sounding territory definitely shorter than what you'd normally refer to as slapback. If you give us a soundclip I can tell you if yours is acting correctly.

Definitely not chorus territory. Hit the link below:
https://www.dropbox.com/s/i5tchcd46oo1vim/Voice0001.mp3?dl=0

[bluebunny]

I think the LED idea was from Jon Patton.

Jon's LED was on pin 7 in his Hamlet delay and is there to avoid distortion in the PT2399.

[slacker]

Definitely not chorus territory. Hit the link below:
https://www.dropbox.com/s/i5tchcd46oo1vim/Voice0001.mp3?dl=0

Somethings not right there. I would start by checking for bad connections or wrong component values around the BC560/2N3906 transistor also make sure the transistor is the right way round.

[Cozybuilder]

I think the LED idea was from Jon Patton.

Jon's LED was on pin 7 in his Hamlet delay and is there to avoid distortion in the PT2399.

Credit Merlin Blencoe for this solution to the latch-up problem on the PT2399, it works great! See P.37 of the Little Angel thread.

[Sanguinicus]

Somethings not right there. I would start by checking for bad connections or wrong component values around the BC560/2N3906 transistor also make sure the transistor is the right way round.

Transistor is the right way, the 220R and 39k resistors are correct and go to the right pins on the transistor.

[Sanguinicus]

Well that's weird. i was just mucking around, making it self oscillate and stuff and now the minimum delay is a lot lower. I wonder why this is. I didn't change anything. Seems to be working better now.

[WorthTheWords]

Sorry for my late reply - I moved to a different city this last week and haven't had internet access.

In addition to slacker's advice, since you're getting the modulated noise and the clean signal, it seems to me that the short/cold solder joint must be in between the input gain stage and the input of the delay chip. If it was the feedback loop, then you'd get one repeat and then nothing.

Also, when things spring to life when you move them: early on in my DIY'ing, I often had issues with wires, specifically right where they connected to the board. I didn't have a good wire stripper back then, and I was nicking the wires so much in stripping the ends that they were breaking when I'd flip the board around in debugging. Just something to notice in case it applies here.

Thanks to both slacker and Taylor for their help. I still haven't able to get mine working properly, and instead of making progress, I feel like I'm moving in the wrong direction. Maybe from too much messing around with it- I've had a few of the small metal circles at solder points come detached from the board. This makes soldering nearly impossible, and I don't think connections are being made at these points. Is there anything I can do about this? I'm considering just ordering a new board and starting fresh.
Thanks again!

[Taylor]

It might be possible to make the connections that have lifted off the board by running wires or point-to-point connecting those parts, but if there are more than a couple, it could be quite fiddly. If you post a photo of which pads are lifted I could give you some ideas where to reattach them.

Your soldering tip should be hot enough to get the solder molten very quickly, so you can remove a part without cooking the copper off the fiberglass. Don't know what your soldering setup looks like but this is why a proper soldering station with temperature control makes life so much easier and your builds more robust. Aoyue makes cheap but adequate ones if it's tough to make the jump to something nicer like a Weller or whatever.

[Sanguinicus]

I did say when it's working I'd post the slide on decal and svg file. The box is primed, I just need to buy some paint. I should have some pictures in January some time. I like to let the box gas out for a few weeks for both the basecoat and clearcoat. I'll post the svg file then. Just so nobody thinks I'm abandoning haha. I think it's a pretty spiffy graphic.

[slacker]

Look forward to seeing it.

[WorthTheWords]

Yeah part of my problem is definitely my soldering set up, and I've known that. But when it comes to paying the money for a new iron, or a new pedal build- I always want to go for the new build! I'll have to just bite the bullet and get a new iron soon. Thanks for your suggestions.

I'm either not allowed to post an image, or I can't figure out how...   

But if looking at the top of the PCB in normal orientation, I think my problem pads are:
1-The left hole for the 20K resistor just under the feedback pot (where the dub madness switch attaches)
2-The left hole for of the 240K resistor on the right (where the LFO waveshape mod attaches)
3- the right hole for the bypass stomp.

As always, thanks for your patience with these newbie questions, and THANKS for your help!

Joel