Problems with Rebote 2.5

[simop]

I started building Rebote 2.5 and got it working pretty easily. First I tested it without bypass switch, LED or DC jack. It worked, and I liked it's sound. Then I added those, and it didn't work anymore. I removed them, but it still doesn't work. I've checked everything a zillion times but it still doesn't work. I'm so frustrated...

1.What does it do, not do, and sound like?
It repeats the signal only once even if the repeats-knob is at maximum and the sound is distorted. Here's a sample with all knobs at maximum: http://koti.mbnet.fi/simopot/temp/rebote_clip.mp3 The recording is bad - it's not really that distorted.

2.Name of the circuit = Rebote Delay 2.5

3.Source of the circuit (URL of schematic or project) = http://www.tonepad.com/project.asp?id=51

4.Any modifications to the circuit? No.

5.Any parts substitutions? If yes, list them.
24k => 22k
240k => 237k
5pF => 4.7pF

6.Positive ground to negative ground conversion? No.

7.Turn your meter on, set it to the 10V or 20V scale. Remove the battery from the battery clip. Probe the battery terminals with the meter leads before putting it in the clip. What is the out of circuit battery voltage? => 8.66
Now insert the battery into the clip. If your effect is wired so that a plug must be in the input or output jack to turn the battery power on, insert one end of a cord into that jack. Connect the negative/black meter lead to signal ground by clipping the negative/black lead to the outer sleeve of the input or output jack, whichever does not have a plug in it. With the negative lead on signal ground, measure the following:
Voltage at the circuit board end of the red battery lead = 7.85
Voltage at the circuit board end of the black battery lead = 0.00

IC1 (PT2399)
1: 5.03
2: 2.51
3: 0.01
4: 0.01
5: 2.43
6: 2.51
7: 0.10
8: 0.61
9: 2.52
10: 2.52
11: 2.52
12: 2.52
13: 2.43
14: keeps changing all the time (around 2.3 - 4.5)
15: 2.52
16: 2.52

IC2 (TL072)
1: 3.62
2: 3.62
3: 3.58
4: 0.00
5: 2.90
6: 3.60
7: 3.58
8: 7.13

IC3 (78L05)
1: 5.03
2: 0.00
3: 7.13

It seems to drain the battery pretty fast since after doing the above measuring that took about 5 mins, the voltage of the battery has dropped to 8.49.

Here are some close-up pictures of my Rebote (about 2MB each).

http://koti.mbnet.fi/simopot/temp/rebote.jpg
http://koti.mbnet.fi/simopot/temp/pcb_front.jpg
http://koti.mbnet.fi/simopot/temp/pcb_back.jpg

The PCB is pretty messy after all soldering and un-soldering.


Any help would be appreciated! I've spent hours debugging this but I can't find the reason for this strange problem.

[fixr1984]

Just from looking at the pictures I would say to double check for solder bridges.
On the third picture, upper left looks like there is maybe one there. Also where the input and
ground connect to the board looks a little close to me.

[simop]

Thanks for your reply.

Neither one of those is a solder bridge. Checked them with a multimeter and a magnifying glass. As I said, I've checked everything many times.

[composition4]

I know you said you checked everything, but did you try replacing your pots? I built a rebote a few weeks back and had a few troubles - turned out to be an intermittent pot.

Probably not it, but think it may be worth a look

Jonathan

[simop]

I didn't try replacing the pots but I checked them with my multimeter and the resistances were ok. Thanks anyway.

[scaesic]

Get rid of that possible bridge on the top left.

Run solder over the rest of these, they look like they could be dry joints.

Finally, the second from the left looks like the solder pad has been removed, if so you'll have to improvise with a peice of wire.

[simop]

Get rid of that possible bridge on the top left.

It's not a bridge though in the picture it looks like one.

Run solder over the rest of these, they look like they could be dry joints.

They don't look that bad in "real world". I checked them anyway.

Finally, the second from the left looks like the solder pad has been removed, if so you'll have to improvise with a peice of wire.

What do you mean by "the second from the left"?

***

I did measurements again, this time with a 9V wall-wart that gives 9.49 volts unloaded.
IC1 (PT2399)
1: 5.03
2: 2.51
3: 0.00
4: 0.00
5: 2.39
6: 2.51
7: 0.16
8: 0.56
9: 2.52
10: 2.52
11: 2.52
12: 2.52
13: 2.43
14: 4.92
15: 2.52
16: 2.52

IC2 (TL072)
1: 4.73
2: 4.73
3: 4.69
4: 0.00
5: 3.80
6: 4.69
7: 4.72
8: 9.42

IC3 (78L05)
1: 5.03
2: 0.00
3: 9.39

I also tried removing the PT2399 from its socket. Then the sound was not distorted (there was no delay of course). Does that mean that the TL072 is working and the problem is in this area? I'm pretty sure that some of the components is broken since I've checked the PCB, solderings, connections etc so many times. How easily does a PT2399 brake? I have actually two of those and I tried the fresh one earlier. The circuit might have had some other problems then and therefore both of my PT2399's might be broken. Is there a way to check whether it's working or not? Could the capacitors or resistors be broken?

[simop]

I said I had checked everything many many times. I decided to check again before trying a new PT2399 chip. I found a cold joint between 0.001uF capacitor and 24k resistor. Now it's working. Thanks for everybody.