Rebote 2.5 troubleshooting issues

[themosscollector]

I am pretty new to the world of diy. I made an attemp to build the Rebote 2.5 form tonepad.com and i cant seem to get it to work. the signal passes through fine when the effect is off but i get nothing when the switch is engaged. i checked for continuity and solder bridges but couldnt find anything wrong there. i started measuring voltages at all the ic pinpoints so i could post the values. trouble is, they keep on dropping. for example, when im finished going through pins 1- 16 on the pt2399 chip and then go back through, i am getting different lower readings. after seeing this, i check the battery voltage and it had dropped from 9.7 to 8.5. what is causing the battery to be drained? another thing i noticed was that when taking a reading on pin 12 of the ct2399 chip, the DMM beeped and flashed a lightning bolt. not sure whats going on with that. im a total newbie to electronics so any help would be greatly appreciated. thanks.

[themosscollector]

i just went over what looked like a couple solder bridges. i plugged in the battery to see if it was fixed and nothing. I am still getting some serious drainage on the battery. When I plugged it in, it read 8.95v and after a couple minutes of screwing around with the pedal, i took the battery out and measuerd it, it read 6.5v the voltage seems to slowly come bact to the battery once it is removed. whats happening here?

[chilecocula]

You should check for continuity between the ground and 9v traces, it looks like your battery is draining because of a short circuit.

[themosscollector]

yeah.. there is continuity between 9+ and ground. i looked all over and didnt see any bridges. the only place where it looks like it could bridge is  the area around the 5v regulator and the area around the 2 47 uf caps there. any ideas?

[PerroGrande]

We've got to clear any issues with excessive current first, as they may be the cause of the other issues you are experiencing.

This effect should not pull down a healthy battery as much as it seems to be doing.  Something, somewhere is creating a low resistance path to ground.  Unfortunately, there can be numerous causes of this. However, it is always wise to check the "simple" items first.

1) Solder bridges, blobs, and the like.
2) Leads touching where they shouldn't
3) Incorrectly oriented components (IC reversed, transistor mis-oriented, electrolytic cap polarity wrong)

Then on to the more subtle stuff...

4) Defective component (bad filter cap, bad IC, etc)
5) Incorrect value installed somewhere
6) Simplify and troubleshoot

So -- after checking the basics, I might be tempted to pull out the 78L05 regulator and re-test for excessive current. By doing this, you'll be able to determine if the problem is with something on the 9V side of the circuit or the 5V side.

Just a few ideas...

[themosscollector]

ok, i checked for bridges and shorts...didnt see anything although i still have continuity between + and ground. all the leads seem to look like they are supposed to. all the caps are oriented correctly. im pretty sure both ic chips are in the correct way based on pictures i have seen but just to be sure...IC1 (pt2399) should have the dot on the chip enclosure at the bottom and the notch at the top and IC2(tl072) should have the dot on the chip enclosure at the bottom right. (this is if you are viewing the board as it is shown in the layout). IC3 is oriented with the flat side facing down like in the layout. i assume this is right?

so if this is all correct, where should i test the board after i pull the regulator and what should i be seeing?

thanks again for taking the time to help.

[Zedmin_fx]

I just fixed one for a guy turned out to be a bad ic, it was tl072, I had alot of hum and no signal until I took it out. go look at the wires and make sure the yare all corectly placed.

[Zben3129]

Check to make sure the values of the side by side 12k resistors are correct. Also, check the resistance between the bias trace (orange on layout) and 9v, and also with ground. A bridge near the regulator or 47u cap as you suggested would cause the problem you are experiencing as well.

Zach

[themosscollector]

the resistance measurment between the bias trace and the 9v reads 0.006  the resistance is the same between the bias trace and the ground.
as far as the 2 12k resistors, one is reading 6k and one is reading 5.9k 

[oskar]

the resistance measurment between the bias trace and the 9v reads 0.006  the resistance is the same between the bias trace and the ground.

But if you have a ~0 reading of resistance from Vbias to 9V then why is the 12k resistor from Vbias to 9V 6k. It should also be ~0 ohm.
The Vbias net goes from the 12k divider/47uF cap to a 1k and a240k resistor. It doesn't include the other side of these resistors!

as far as the 2 12k resistors, one is reading 6k and one is reading 5.9k 

as there is a bridge between 9V and ground they are now connected in parallel.

[themosscollector]

im pulling my hair out trying to find this bridge. just to humor me, is there anything else that could potentially cause continuity between 9v and ground?

[PerroGrande]

An incorrectly installed polarity protection diode could do that...

[Zben3129]

There isn't one in this circuit  I see myself toasting mine at some point.

Check polarity of the 47u caps right in the middle of the board

Check the pinout of your 5v regulator

Zach