[HELP!] - Deep Blue Delay Clone - PedalPCB "Seabed" Delay [ IC pin voltages]

[rivercrafter]

Hi guys,

I assembled 2 mad professor deep blue delay clone using PedalPCB.com's "Seabed Delay" PCB. https://www.pedalpcb.com/docs/SeabedDelay.pdf

No mods or value subs. One works great but I'm not getting delay out of the other one. I put the PCB's together at the same time. I didn't have a cap tester at the time (I do now) but I did measure and verify all the resisters before installing.

LED comes on, I get a little volume bump when adjusting the level but no delay. No hum or grounding noises, nice and quiet.

I measured the voltage from the PT2399, compared them with the one that's working, and found that the voltages are ok except two of them [pin 7 - CC1 /pin 8 - CC0].

Here are the measurements on the one that is not working. They are nearly identical to the one that is except that the working pedal reads .13v on pin 7 and .67v on pin 8.

PT2399
1 – 5.05
2 – 2.52
3 – 0.00
4 - 0.01 (this is .02 on my working pedal)
5 – 2.58 (this is 2.65 on working pedal)
6 – 2.51
7 – 4.38
8 – 4.38
9 – 2.51
10 – 2.51
11 – 2.52
12 – 2.50
13 – 2.51
14 – 2.51
15 – 2.51
16 – 2.51

OP275
1 – 4.25
2 – 4.17
3 – 4.15
4 – 0.00
5 – 4.15
6 – 4.17
7 – 4.13
8 – 8.34

78L05 regulator
I – 8.34
G – 0.00
O – 5.05

Measured the electro caps on the board with power off and they all matched their values, the board I think it's ok, wires & connections are all good. I touched up the solder joints looking for cold solder points. I switched out the IC's with the pedal that is working and all of the IC's work.

Hoping someone with more experience than I can see the problem?

Thanks!

[stringsthings]

Looks like you've got a short somewhere.  I'd check around pins 7 and 8 of the PT2399 and see if they're shorting to a trace.
Looks like they're also shorting to each other.

[Kipper4]

Check the gnd connection on the 2x 100nf.

[duck_arse]

pin 3 should always be shorted to pin 4 to avoid some of the latch-up problems. your pin 4 suggests they aren't connected. same goes for your working pedal, should have pins 3 & 4 the same voltage, 0.00V.

[rivercrafter]

I found a lifted trace between pin7 and the 100nf across from it, I added a jumper there and also shorted pin 3 to pin 4. I've been over and over it and can't seem to find the short. I've had it in and out of the box so many times the delay pot broke off from bending back for access to the solder side so time to take a break.

In my original post I had the pins labeled incorrectly. Pin 7 would be AGND and pin 8 is DGND.

The voltages have changed a bit though, here's the new readings.

PT2399
1 – 5.05
2 – 2.51
3 – 0.00
4 - 0.00
5 – 2.51
6 – 2.51
7 – 3.80
8 – 1.91
9 – 2.51
10 – 2.51
11 – 2.51
12 – 2.53
13 – 2.51
14 – 2.50
15 – 2.51
16 – 2.51

OP275
1 – 4.26
2 – 4.19
3 – 4.16
4 – 0.00
5 – 4.16
6 – 4.19
7 – 4.15
8 – 8.37

78L05 regulator
I – 8.38
G – 0.00
O – 5.05

[duck_arse]

may we see some photos of your build, and the offboard parts?

[rivercrafter]

Sure thing, here are some pics. Sorry for delay, I built a Klon(e) last weekend that of course also needed troubleshooting (the B100K dual gang pot was shorting on the PCB, I had to remove and reinstall with more of a gap between the pot and pcb - took me a few days to track down!).

Looking at this one again, I had pulled out and replaced the 2 100n caps that Kipper4 suggested I check the ground on, I am still learning how to remove components without damaging the PCB and I think I pulled out or pushed through the solder points on a couple points around those caps.

I really like the one that works and was going to make another for a friend. I picked up a couple of Aion "Vector" pcbs which is their Deep Blue Delay clone - wondering if this PCB can be salvaged or if I screw it up too far and should just salvage as many components from this board as I can and start over on one of the vectors. Once I got this one cleaned up a little it looks pretty beat up.

[patrick398]

I am still learning how to remove components without damaging the PCB and I think I pulled out or pushed through the solder points on a couple points around those caps.

In my experience with working with PCBs [i usually use vero/stripboard] sometimes it is wise to sacrifice the component rather than  risk damaging the trace or solder pad. Cutting out the component first then using tweezers to remove the remaining legs is often way easier...especially with things like pots...as hard as it is to sacrifice them sometimes.

I'd be wary of that 22nf below the B50K pot, C11 i think. Not necessarily toast but maybe best to replace caps with chunks melted out of them.
And also what is that gargantuan component around R12?

[duck_arse]

gigantor looks like a styroseal/polystyrene/styroflex cap to me. as long as it's the right value and not leg-shorting [or burns in the body] to something, it should be OK. that burnt 22nF should go, tho.

on the board back, see where the blacking has been scraped and the red/brown of the copper shows thru? there is a patch on the very left, between 4 and 5 rows down, where the black is scraped and there is apparently nothing under it. have you busted that track?

[rivercrafter]

Yeah, the gigantor is a styroseal/polystyrene/styroflex - it was my first time ordering parts. Works fine in the other one. I burnt that cap at C11 pulling the solder out of the holes for the delay pot that broke and will replace. Nice catch on the broken line, I think it's a lot easier to see in the photo but it's there for sure. I'll swap out the 22nf cap, solder in a new pot and run a wire to jumper the broken line at the left...maybe that will do it!