Deep Blue Delay Vero

[Locrian99]

Hello,

I am building a pt2399 based vero clone of the deep blue delay.   Currently I am passing signal through the pedal but am getting no effect.   Although it does change the tone of my clean signal considerably, almost sounds like a big muff tone stack with the knob turned all the way to the bass side, and I swear I hear a little bit of reverb.  I've spent hours double checking this thing now and don't see any obvious to me at least issues with it.   I've triple checked component placement and cuts.   Checked for continuity between prior to mounting components.   That said I did have a mistake while doing the cuts, under the op amp, didn't have another piece of vero large enough and I'd just made 20+ cuts so I bridged over them with piece of wire.   Also the double link under the pt2399 since they were right next to each other and I couldn't for the life of me get two wires to go in one hole I just ran the link the full way and bent it out the other side to link with other strip and soldered them together. 

Here are my voltages:
OP275

1-4.19  5-8.51
2-4.25. 6-4.33
3-4.25. 7-4.25
4-0.      8-4.25

PT2399
1-5.0.  16-0
2-2.48  15-3.56
3-0.     14-300mV
4-0.     13-2.48
5-3.12. 12-3.6
6-2.48. 11-2.48
7-2.3.   10-2.48
8-2.3.    9-3.57

Here are known voltages from a post I found, and from piecing info from others they seem accurate




Here is the layout I used




Pictures of the circuit








Schematic




The layout has an added volume pot that isn't in the schematic. 

Also read through electrosmash's article on the pt2399 trying to find some insight as to why the voltages are so off and failed im sure they info is there im just not knowledgeable enough to see it.  Hopefully I'll get there. 

Thanks

[anotherjim]

Pin16 of the 2399 either has a short to 0v or is not connected. If there isn't a short, the most likely (although rare) is the IC leg does not actually make contact in the socket. Sometimes those turned pin sockets can lack the spring contact insert intended to grip the leg and Murphy's law says it won't touch the sides of the socket cup either. Nowadays I buy 40way female turned pin header strips and cut them up to make IC sockets and I've had runs of 2 or 3 without springs. I still prefer them though as it leaves the top of the board under the chip free to access so I just test them with a component lead first to check for grip.

[Locrian99]

Awesome thank you.   I'll
Check it out after work.   I had a hell of a time getting the chip in the socket so that makes sense. 

[duck_arse]

it looks to my tired old eyes like a 10k resistor missing from that pin 16 track.

[Locrian99]

it looks to my tired old eyes like a 10k resistor missing from that pin 16 track.

Man I don't know how I would've missed that, literally went over twice looking at the layout checking the board but I do think you are right from the picture, had another one on my phone that looks like it as well.   When I get home tonight I'll check for sure.   Yea it's for sure not there there's a clear view of the pin it should be going into.    How in the .... Did I keep missing that... hopefully that solves the problem not sure that would change the other voltages that are off though. 

[Locrian99]

That fixed 9-16 to 2.48 have delay signal coming out of 14 and 15 has the mixed signal, have it at the 10k right outside of it by the time it gets to the other side of the 10k it's faint.   By the time it gets to the other side of the 10k coming off that rail back toward the op amp it's gone.   Voltages at 7/8 still aren't at 0 and 5 is at 3.x but I think I recall reading somewhere those don't have to be at 0.   I'll look at it some more tonight when I have a bit more time. 

[Locrian99]

Solder joint in the negative side of the cap right above the OP275 looked questionable.   Hit it and a few others around board, and it works!

[Locrian99]

So this still sounded off to me.   Kind of bassy and compressed best way I could think of describing it was a big muff tone stack turned all the way to the bass side, and seemed a bit below unity.   So I decided to build a second one just to see if that was how it sounded though the demo of the actual dbd didn't sound that way.   It was a night and day difference in sound.   I traced it and it sounded good until the output of pin 7 in the op amp.   Well I put a 100n ceramic cap for c20 instead of 100p.   

[ElectricDruid]

Good work!

Both for sticking at it and finding a way to work out where the problem was (aah, if only we *always* had a known-good unit to hand!) and also for the final spotting of 100n in place of 100p. That's easy to miss.

[Locrian99]

It was actually not too bad.  Since it was affecting the dry signal I knew it had to be on the top half of the board (at least that made sense to me).   And since it sounded like all the highs were being filtered out I figured it had to be a cap.   I think I spent more time questioning whether that was how it was supposed to sound then anything.