Echo Base - a new PT2399 delay

[soggybag]

Your problem is somewhere later on then, it's normal to get very little or no signal on pin 16, if you have signal on pin 15 then signal is getting to the PT2399. Do you get delayed signal on pins 12 and 14? If you do trace the signal through pins 10 and 11 of the CD4066 and the wiper of the level pot, hopefully this will show where the problem is.
If you don't get signal on pin 14 the problem is somewhere around the PT2399.

I'm definitely not getting sound at pin 14, 10, or 12, only pin 15 has sound when I check with the audio probe. I'll check all of the parts in that neighborhood.

Thanks again for the help!

[soggybag]

After a second inspection, the audio probe reveals audio at pins 15 and 9 of the PT2399. I'm getting audio at the output of the effect, but no echo.

If understand correctly, audio should go in at pin 15 and come out with echo at pin 14. In between the signal should run through the two built op-amps at pins 9 and 11.

I made the mistake of not using a socket. It's really difficult to get the chip out of there to determine if it is the problem.

[kingswayguitar]

ok - help please with the bypass switch
i'm trying to orient it correctly on my enclosure


http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=44171

if the bypass switch is open (that is, the base of the 2n5089 is NOT grounded), the pedal is off

correct?

thanks

[slacker]

Yes that's right.

[KNA]

I have ran into some weird noise issue that seems to be related to the power supply in some way, but I cant figure out whats wrong. The pedal gives a noisy, compressed fuzz the first 10-20 second when it's first plugged in and I strum relatively hard, but then it disappears and the pedal sounds great and all controls seems to work as they should. When I try and disconnect the power and the start over, the same issue appears. It obviously seems to be related to the power, but I dont know where or for what I should look for errors. I have replaced all IC's and transistors at least two times without success. Any ideas on this? It super annoying to be this close to have it working properly...

[KNA]

Anyone?

[tombaker]

Sounds odd, have you tried a different power supply? Is it the only pedal you're running off the supply? What mods, if any, have you done?

[KNA]

Yeah, I think its pretty weird since everything works fine when the noise disappears. I have done the waveshape mod which works fine, but I haven't tried another power supply since I don't have any at hand, but I have thought of that as well. I will try a different amp and supply as soon as I get the chance.

[slacker]

If it only does this when you first power it up it is probably just the capacitors for the +9 and +5 and Vref charging up, and nothing to worry about. Until these are charged the opamps won't be biased properly and so won't work correctly which could cause fuzz.

[KNA]

Ok, that makes sense, thanks! So this is something I'll have to live with? Guess the problem will remain even if I replace the caps, or could that help?

[soggybag]

Argh!
After testing everything backwards and forwards, I decided to desolder the PT2399 and put in a socket. I put in a new PT2399 and, it started working but, the echoes were distorted. I tested another PT2399 and it sounded fine. I think the first two chips were bad. Not sure where I bought these, maybe futurelec, I can't be sure, I bought them more than a year a ago. I had read people saying that not all PT2399 chips were created equal.

Note to self, in future always use a socket PT2399!

Thanks again for all the help.

[soggybag]

Measuring pins 9-16 on the PT2399, I was getting weird numbers, like 3.8V and 4.56V. These pins should all be 2.5V. The only thing that I could think of that would throw these off is if the internal bias was not right. Each of the pairs 9-10, 11-12, 13-14, and 15-16 represent the output and non-inverting input of an internal op-amp. The inverting input to each of these op-amps should be biased at half the supply voltage, and so the output should settle at the vref for the chip.

As a test I disconnected the power and measured the resistance between each pair of pins: 9 and 10, 11 and 12, 13 and 14, and 15 and 16. I compared the resistance on both the working version and the non-working. The resistance was the same on both. So the surrounding parts should have been correct.

In the end the only thing I could think of was that the internal vref was off.

[wilmore]

Hi, i'm trying to build this project.. At the moment the effect doesn't work, i listen only modulation effect but no delay, also feedback control doesn't work. With audio probe signal stop at C16, is it normal or that's a problem here? I tried to change capacitor yet. Maybe Diodes?

Thank you

EDIT: Offset voltage are ok for PT2399 and LFO, not sure about 4066, U3 have 2,5 V on pin 5 instead 5V, a problem on Vref too?

[miique]

Alo, quite a noob here. Built this circuit using two different layouts (Anonfaceless' and Dimebugg's, bad idea, I know, I just thought maybe it would spare me from the debugging process) and I get dry signal on both; I did try replacing the 2399 but I guess there's still the chance they're faulty since I got both of them from the same store (I also have a few other ones which I don't really trust at all).
Either way, before looking for another 2399 replacement, or posting pics and voltage readings, I wanted to know how to wire it without potentiometers so as to leave it in a functional state and make sure the problem isn't the pots (I made two different boards but used the same pots). Also, could this be caused by diodes not pointing the correct way? I'm pretty sure I placed them correctly but still feel the urge to ask

By the way, I also have two question about Dimebugg's layout:
Is it ok if I just leave out the 1N4741?
I'm not sure I understand the bypass and tails switches wiring in the PDF, could someone explain it to me wire by wire?

[garcho]

First of all, welcome to the forum!

READ THIS if you want a response that helps you more.

spare me from the debugging process

Ha! Yeah right. And yes, it is definitely a bad idea, dumb idea even.  

If all you get is dry it could be a problem with the 4066 and related soldering. Or a number of other things.

I wanted to know how to wire it without potentiometers so as to leave it in a functional state and make sure the problem isn't the pots

More work than it's worth. Turn power to the pedal off and check the resistances between the pots' terminals. Then double check your wiring. It's not any less complicated to wire up (and debug) static resistors. Unless a bunch of solder leaked into the pot, they're probably just fine. There might be an issue with the 'level' pot. It could potentially be mis-wired in a way that would prevent any processed signal (delay) and that's why you only get dry.

Also, could this be caused by diodes not pointing the correct way?

Are you talking about the 1N4148s? As long as one "points" the opposite direction of the other, you're all good.

By the way, I also have two question about Dimebugg's layout:

Then share a link to the layout.

Is it ok if I just leave out the 1N4741?

Why would it be ok?

I'm not sure I understand the bypass and tails switches wiring in the PDF, could someone explain it to me wire by wire?

Why not ask Dimebugg?

That's asking a lot from total strangers online when you don't go through the work of proper debugging, or use the forum's guidelines for posting about debugging, or providing any pictures of your wiring, or providing a link to the layout, etc.

[miique]

That's asking a lot from total strangers online when you don't go through the work of proper debugging, or use the forum's guidelines for posting about debugging, or providing any pictures of your wiring, or providing a link to the layout, etc.

Thanks for your reply, Garcho!

I actually breadboarded Dimebugg's layout using static resistors and I can affirm it works perfectly fine now, it seems some of the pots I've been using are faulty (or maybe I overheated them?).

Either way, I thought it'd be logic to assume the same solution would apply to Anonymous Faceless Coward's PCB since I was having the same problem, but nope, I breadboarded the whole wiring and I'm still getting a dry signal, I'm guessing it could be a problem with the 4066, since it seems to be the only substantial difference between this and Dimebugg's layout, I used two different 4066s (pretty sure they're from different manufacturers, too), and also tried a 4016 like they mentioned in some part of the thread, but neither of these seemed to change anything. Another difference is for this one I used a polarized electrolitic cap where it asks for a 1uf non-polarized cap, but I think I've read somewhere in the thread this should be fine?

Here's the layout I'm using:

http://img5.blogs.yahoo.co.jp/ybi/1/78/55/anonymousfacelesscoward/folder/903906/img_903906_23693577_0?1211991255

Here are some pics of the PCB:

http://i.imgur.com/v9DMK9nh.jpg

http://i.imgur.com/fTCYFa9h.jpg (sorry about the hair)

And lastly, here are my -pretty odd- voltage readings:

2399
1. 5
2. 2.5
3. 0
4. 0
5. 5
6. 4.1
7. 0
8. 4.1
9. 0.6
10. 4.3
11 to 16. 2.5

4066
1. 2.9
2. 2.9
3. 0
4. 0
5. 0
6. 0.12 off 0.8 on
7. 0
8. 9.2
9. 0 off 9.2 on
10. 2.9
11. 3
12. 7.6
13. 8.8
14. 9.3

TL072 (i'm not sure which is U3 and which is U1)

1. 5
2. 5
3. 5
4. 0.7
5. 4.7
6. 5
7. 5
8. 8.6

1. 5
2. 2.6
3. 5
4. 0
5. 5
6. 5
7. 5
8. 9.3

5089
E. 0
B. 0.61 off 0 on   
C. 1.4  off 8.8 on

It'd be greatly appreciated if someone could tell me which track should I trace or some idea of where to look since I really have no idea what could be giving me these values; the 7805 seems to work just fine, it's getting 9v and outputting 5v

[Uriziel]

Hey,

So I decided to build this pedal and I can say that I succeded and on the first run aswell... right after assembly... no problems to date...
I took the ver 2 schematic and made my own layout... this one is with SMD components... someone few pages back said it would be nice to see one so here it is

https://www.dropbox.com/s/9dnfga10xeww3sb/IMG_0355.JPG
https://www.dropbox.com/s/hfdvgt7k4ypqkl4/IMG_0356.JPG
https://www.dropbox.com/s/bxbm84c2oye2zap/IMG_0357.JPG
https://www.dropbox.com/s/u0ll832p2kwhk8p/IMG_0361.JPG

Thank you guys for you contribution and thank you for making this public...

[slacker]

Wow that looks amazing nice work. I like the unusual layout.

[Uriziel]

Thanks! Unusual in what way, if I may ask?

My idea was to group all the functional blocks and put them together, since i did it double sided I had plenty of room to do that, nevertheless some components had to be put further apart than other since i wanted everything pcb mounted minus the leds and a switch... the pots take the majority of space.

I added a dual color led for the boss tails switch and on the bottom layer there are some zero resistors so I may swap the dc jack's tip and sleeve since some adapters have sleeve positive and tip negative and vice versa, just in case... another technique would be to add a rectifier bridge, but then you would have to accommodate the voltage drop (about 1.4V) and probably would need a supply that is 10.5-11 volts and that would be maybe not so readily available, but then again 12V PSU - diode bridge - linear voltage regulator or LDO for 9 volts would also do the trick, probably I wouldn't ever need it anyway since I know what kind of plug i need but there are plenty of dumbusers out there that just expect everything to be plug and play.

[electricmimesis]

Hey All,

I hope this is the right place to post for questions. I've just built the echo base and everything seems fine except that the dubmadness mod is not working as it should. I purchased the board from music pcb and followed the instructions provided in the manual. What happens is that when the toggle is on I get heaps of feedback as expected, but when it's off, the feedback pot is not working at all and I only get one slap-back. When I remove the dubmadness mod the feedback pot works just fine.

Any ideas on where to start?

Thanks.