I can't get my Rebote Delay to work, please help.

[bobbysatya]

Hello everyone, I've just finished building rebote delay 2.5 circuit from tonepad but no sound came out of it. Not even the clean signal. It has a weird symptom, when I unplugged the power supply and I touch the output jack with my finger, it made some noise but when I plugged the power supply in, the noise was gone even when I tapped it several times. As for now, I'm pretty sure I did not make any soldering mistake as I have checked it many times. Oh and I also measure the voltages of all three chips pins as follow :

Op Amp :
1-4.58v
2-4.58v
3-4.57v
4-0v
5-4.47v
6-4.57v
7-4.58v
8-9.09v

78L05
In-9.09v
G-0v
Out-5.13v

PT2399
1-5.13v
2-2.48v
3-0v
4-0v
5-3.1v
6-2.48v
7-0.635v
8-0.68v
9-2.48v
10-2.48v
11-2.48v
12-2.48v
13-2.48v
14-2.48v
15-2.48v
16-2.48v

I hope this voltage measurement will give you clues about what has gone wrong with my circuit. I'll try to post the picture of my PCB tonight. Thanks in advance. Have a good day everyone.

[duck_arse]

your voltages look ok, so we'd be expecting the dreaded "wiring error". photos. do you have an audio probe?

[bobbysatya]

Sorry, for some reason I was unable to post the photo tonight. Pardon my ignorance but what kind of device is an audio probe? I tried to trace the error by removing the PT2399 and plugging the output jack directly into pin 7 of the op-amp which is the output of the circuit's first stage to see if the chip worked allright. But the problem persists. That means NO SIGNAL is entering the next stages. I was looking for solder bridges, bad joints etc to no avail. The wiring seemed OK no matter how many times I looked at it. This is frustating, this is my fourth build of Rebote Delay and I had no problem with previous three. Guess I'll etch a new PCB and move all the components to the new one.

[slacker]

...what kind of device is an audio probe?

Have a look here http://www.diystompboxes.com/wiki/index.php?title=Debugging it's basically doing what you've already done by connecting the jack to pin 7 of the opamp. There's only 3 or 4 components before the opamp on a rebote so if you probe all the points between the tip of the input jack socket and the opamp you should find where the problem is fairly quickly.

[bobbysatya]

I see. This circuit is acting really weird. It passes no signal whatsoever but I could still hear some noises when I touched the tip of the output jack. The weird part is when I plugged the power supply all the noises were gone as if they were shunted to ground completely. I suspected that the pin 7 is either shorted to ground or vb but nothing confirmed this. I even replaced the chips too but nothing changed. What do you think caused the pin 7 to pass no signal?

[slacker]

Pin 7 could be shorted to pin 6 or pin 6 could be shorted to pin 5, either of those would give no sound. Have you checked the signal is getting to the board?

[bobbysatya]

Yes I have. I plugged the output jack directly to the other side of C1, the sound was there. But it didn't make it through the pin 7. I tought the chip was broken but then I tried sticking it into my lovepedal kalamazoo clone and it turned out ok. That means it's extremely likely that I'm having a short somewhere in the circuit. Gotta check it in the morning it's getting late here.

[bobbysatya]

Bad news guys, I couldn't find any short in the circuit. All the connections seemed OK. Is it possible that I'm having faulty components? In worst case, I've etched a new PCB I'll just move the components into it tomorrow.

[vigilante397]

No attempt at pictures? Those can be very helpful in debugging.

[bobbysatya]

Too late, I have depopulated the PCB. Nevermind, I'm just gonna rebuild with a new PCB and old parts. The previous PCB was kinda messy anyway. My dulled drill is to blame.

[bobbysatya]

Done! A newly etched PCB solved all the problems. I still have no idea what had gone wrong though.

[duck_arse]

can we have a photo of the old board, solder side, even tho it has no parts? give us something to look at!

[bobbysatya]

Here you go