Echo Base troubleshooting (Sabro's vero)

[stith]

Hey y'all! Tried building the Echo Base from Sabro's veroboard layout and I'm having some trouble. I'm able to get a dry signal, even with the effect engaged, but only when I add an extra 100u filter cap to the output because I'm getting an extra 5v on that line for some reason?? That's fine though, an extra cap is whatever. The real problem is I can't get any more than a VERY faint signal out of the 2399. It's so faint I only just barely hear it with Level and Feedback all the way up. I can't hear any repeats either, but that might just be because it's so quiet.

My voltages at the various pins are all off all over the place and I haven't made any progress on figuring out why myself. Here's the dump!

Schematic/layout is from Sabro, here: https://www.sabrotone.com/vero-layout-for-the-echo-base-digital-delay/
The voltages I used for reference are from slacker's post here: https://www.diystompboxes.com/smfforum/index.php?topic=60662.msg498824#msg498824

Below, parenthesis are my measurements when they differ from what is expected, otherwise just the expected value.

Code Select Expand

PT2399
1. 5v
2. 2.5v
3. 0
4. 0
5. 2.89v
6. 2.5v
7. 0.5v (4.5v)
8. 0.5v (4.5v)
9 - 2.5v (0v)
10 - 2.5v (4.5v)
11 - 2.5v (4.5v)
12 - 2.5v (0v)
13 - 2.5v (1v)
14 - 2.5v (5v)
15 - 2.5v (0v)
16 - 2.5v (3.3v)

4066
All tested with the effect on

1. 4.6v
2. 4.6v
3. 0.4v (5v)
4. 0.4v (5v)
5. 0    (9v)
6. 0.45v off 4.5v on
7. 0
8. 9v (2.7v)
9. 3v on 0.32 off (2.6v on)
10. 4.6v (0)
11. 4.6v (0)
12. 8.5 on (0 on)
13. 8.5 on
14. 9


Both of the 072s  seem correct and are reading in line with that post.

For Q2 I'm using a 5088 due to no 5089s being in stock near me, readout (top to bottom) is 2mV (so, 0v), 1mV, 9v

And Q3, top to bottom: 0.8v, 0.26v, 2mV.

Both of those seem correct to me. I double checked my cap and resistor values, so I'm guessing it's a soldering issue somewhere, but I have no clue where it could be. Any help is very very appreciated!!

[duck_arse]

welcome to the forum.

we, also, have no clue, as you've not posted any photos of what you have built. parts side, solder side, all offboard wirings, please? also, 2mV is not "(so, 0v)", it should read 0V. it may indicate a problem - as does adding a 100uF to the output .....

[stith]

Apologies, and time to necro my own thread lol. Here's some pics. It's a mess!

I discovered today that I'm actually getting repeating feedback (noise only, NOT from my dry signal!) when the modulation switch is ON. It seems to not be affected by the mod speed pot, but the pitch IS affected by the mod depth pot. And I can use the feedback pot to make the feedback build up or die down. So maybe somehow my dry signal isn't getting to the PT2399? I'll look into that now.

Pictures: https://imgur.com/a/LAuoCuS

[duck_arse]

what happened to R9? can you check the colour bands on R36?

you've set us a task, alright. we need better photos so we can see resistor colours and placements, please. and you need to dress all those track cuts, there are some chads a'hanging. then run a knife blade between each of the tracks to make sure there are no shorting blobs or component legs, cause it looks like there is some of those, too.

[anotherjim]

Unless the PT is bad, its pin9 should not be 0v. I'd check it isn't shorting out. The only external connection for it is a capacitor to pin10. The 2.5v you should have is made internally .

[ElectricDruid]

While I recognize that m'learned friend DuckArse might have good points, I'd just like to say that it's a pleasure to see some photos of a stripboard circuit that isn't all black and crusty and covered in blobby solder and god awful amounts of foul crud. This one is like they're *supposed* to look!

Can someone get Snow123 over here to take a look please? 

PS: Betcha it doesn't take 19 pages to get this one working...

[bluebunny]

Can someone get Snow123 over here to take a look please? 

I love you, Tom!

[r080]

The good news is, based on the 5V at the output, your regulator seems to be working.

I don't know what happens when a PT2399 latches up, but maybe that is the cause of your odd voltages, though the Echo Base has a latchup prevention circuit,

Since you have a few different places on the PT with 4.5 volts, it seems you might have a short to Vref somewhere.

Now is a good time to use a multimeter and measure resistance between traces which are not supposed to be connected.