rebote 2.5 voltages...

[roofer1]

rebote 2.5 from tonepad.  i've successfully built a few before...this one has issues.  it is a friend's board, just a few months old.  it once worked but then stopped delaying (when "on" it just makes a straight clean signal, no delay).  i have the 10k resistor in for endless repeats.  here are the voltage mesurements...
as you can tell, the battery is fresh and running about 9.4v or so...
IC1 (PT2399)
1= 9.37
2= 9.39
3= 9.40
4= 9.40
5= 8.89
6= 9.35
7= 8.88
8= 8.88
9= 8.88
10= 8.88
11= 8.90
12= 8.90
13= 8.90
14= 8.89
15= 8.87
16= 8.89

IC2 (TL072)
1= 4.68
2= 4.68
3= 4.68
4= 9.38
5= 4.57
6= 4.68
7= 4.68
8= 0.00

IC3 (78L05)
1= out 9.32
2= grd 9.35
3= in 0.00

any thoughts?  i've checked the solders, rewired the entire thing (all pots, switch, jack, led).  turning the pots has no effect.  it sounds identical bypassed as when on...i checked the switch for connectivety to make sure that it was "switching".

thanks!

[roofer1]

sorry...here's the link for the schematic from tonepad (which i followed to a T, like i said it worked recently...)

http://tonepad.com/project.asp?id=51

[oldrocker]

What jumps out at me is the 78L05 voltage regulator.  If you don't  have a good ground on pin 2 you won't get the 5 volts you need going out.  I found that out recently when building the Princeton delay.  Pin 1 of the PT2933 needs the 5 volts to work.  In fact grounding seems to be a problem with it period.  Pin 4 should be grounded also on  both the PT2399 and the TL072.  It seems supply voltage is going to these.   That said I would check the ground for the whole circuit and start there.

[roofer1]

okay, i checked the ground on those pins (and the other ones that are marked as grounded on the tonepad layout.  so...5 volts to pin 1 of the pt2399 is a must?  well, i am getting about 9.4.  does that mean that the 78L05 is not working?  is it responsible for changing the battery voltage to 5v for the pt2399?  because if it is, it isnt...no what i mean?
thanks for the quick resonse though!

[dxm1]

oldrocker's right. what you should see on the 78L05 is:

In: battery voltage
Gnd: 0V
Out: 5V

I believe the PT2399 has a max working voltage of a little over 6V, so all of those 8's and 9's spell trouble. Once you fix the regulator, you may end up with a fried delay chip...

[dxm1]

okay, i checked the ground on those pins (and the other ones that are marked as grounded on the tonepad layout.  so...5 volts to pin 1 of the pt2399 is a must?  well, i am getting about 9.4.  does that mean that the 78L05 is not working?

Did you wire in a DC adapter plug? Looking at the Tonepad layout you linked to, besides mislabling it as an 'AC' adapter, I see no provision for polarity protection. If someone used an AC adpater, or the wrong polarity DC adapter, the 7805 may have lost it's magic smoke.

[roofer1]

okay i resoldered the 78L05 just to double check the connection and now it is reading battery v at in, 0 at grd and 0 at out.  so it must be cooked...could i use the radioshack 7805 5 volt regulator?  it is a 3 pin like the 78l05 and its right down the street instead of at steve daniel's a week and a half away...

[roofer1]

by the way, yes it does have a dc adapter.  the typical led, 3pdt, dc adapter/battery setup.  any thoughts on that radioshack 7805 5v regulator?  all this pedal posting/troubleshooting is awesome!!!  beats the hell out of sitting over the soldering station cursing the gods...

[dxm1]

okay i resoldered the 78L05 just to double check the connection and now it is reading battery v at in, 0 at grd and 0 at out.  so it must be cooked...could i use the radioshack 7805 5 volt regulator?  it is a 3 pin like the 78l05 and its right down the street instead of at steve daniel's a week and a half away...

Yes, but... The 78L05 is in a TO-92 package, and the 7805 is a TO-220. Besides having larger diameter pins, the TO-220 pinout is 'backwards' from the TO-92. This is hinted at (but not fully explained) in the Tonepad project file. If, looking at the 78L05 with the flat side towards you and the legs pointing down, the pins are left-to-right 1=Out, 2=Gnd, 3=In. The TO-220, with the metal tab away from you and the legs pointing down, the pins are 1=In, 2=Gnd, and 3=Out. So, you would have to install the 7805 'backwards', with the metal tab facing the same direction as the flat side the 78L05 is pointing.

[roofer1]

cool...makes sense.  maybe a trip to radioshack can (once again) solve some of life's problems.  of course then, as you pointed out, the pt2399 could be dead and the whole thing will still depend (once again) on smallbear's services.  i feel like i am a hell of a lot closer to having this thing licked than i was an hour ago.  it is 1:30 here in georgia...bedtime...even though i often dont like to admit, the pedal will still be here tomorrow (or today actually...dangit...)

[oldrocker]

You may get lucky and not have fried the PT2399.  Mine didn't fry when I had that problem but you never know.  Yes the Radio Shack regulator will work if you can get it to fit.
If you're getting 0 volts at all the pins on the regulator that means you lost your 9 volt supply voltage.  So now something different is happening.  Check for 9 volts coming in.  The 9 volts should go directly to pin 1 of the 78L05 so if you're reading 0 volts you don't have 9 volts from the battery anymore.

[Samy]

Your voltages are terribly wrong !
You must check why you have 4V on pin 4 on the TL072 among other things...
On PT2399, you must have 2,5V from pin 9 to 16, pin 1 must be 5V.
On TL072, you must have 9V on pin 8,  4.5V on pin1 and 0V on pin 4.
On 78L05 you must have 9V on the Input, 0V on the middle pin, and in the output, 5V.

Sorry, i don´t have any more voltages on my notes...

[oldrocker]

Yes.  I second what Samy wrote.

[oldrocker]

One more thing.  Are you sure the polarity from the power supply isn't reversed?

[roofer1]

okay...i put the 7805 5v regulator from radioshack in...careful to put it in "backwards" so that its pinout matches the 78L05 i took out.  its doing the same thing...clean unaltered signal when on.  here are the new voltages...
TL072
1= 4.48
2= 4.48
3= 4.48
4= 8.9
5= 4.37
6= 4.47
7= 4.47
8= 0

7805
1= 0
2= 8.92
3= 3.87

PT2399
1= 3.87
2= 6.33
3= 8.75
4= 8.75
5= 3.88
6= 3.43
7= 4.26
8= 8.08
9= 6.31
10= 6.31
11= 4.3
12= 8.64
13= 6.29
14= 3.94
15=6.29
16= 6.29

completely different than the first readings...what does that all mean?  crappers...i thought putting that new 5v reg. might fix it...

[oldrocker]

Well for one thing the voltage on the TL072 on pins 4 and 8 look reversed to me.  Pin 4 should be ground and pin 8 should be 9 volts.  So you need to see why that is and go from there.  Voltage at pin 1 of the PT2399 looks low and also coming from the new regulator.  But I don't think that's significant.  I assume you're using a battery.  Or if it's a power supply make sure it's polarity is correct.  Something power wise seems reversed to me.
If you find that power is reversed you may need to double check that the orientation of the new 78L05 is right or put the old one back in the same way you took it out.
That's what I would do.  If it was me I would put the old regulator back in and orient it the way it was before and reverse the possitive and negative leads of the battery.  But that's just me.

[roofer1]

okay...i am a effing idiot.  wasted my time and more importantly yours...i had the dmm probe on the positve of the battery, hence some stupid readings on that last post...so here goes...one more time, please be patient.  i completely appreciate everyone's imput and i really am asking you guys to overlook a typical new guy mistake.
so with the black dmm probe clipped to ground...
battery= 8.51
TL072
1= 4.26
2= 4.26
3= 4.26
4= 0
5= 4.15
6= 4.26
7= 4.26
8= 8.5

7085
1= 8.49
2= 0
3= 4.89

PT2399
1= 4.89
2= 2.44
3= 0
4= 0
5= 0
6= 2.44
7= 4.48
8= 0
9= 2.44
10= 2.44
11= 4.45
12= 0.10
13= 2.44
14= 4.79
15= 2.44
16= 2.44

sorry about the mixup...i'm a *&^*&^...

[dxm1]

Ok, so the voltages on the regulator finally look good. The opamp voltages are in the ballpark.

I'm not familiar with this circuit, so I'll leave further delay related issues to those that have actually built this.

[roofer1]

does it seem a little weird to anyone that its doing the exact same thing on as when its bypassed?  is there a point on the circuit to test if there is being a delay created?  in other words, a way to see if the pt2399 is doing its thing, but the signal is not getting out...

[roofer1]

at what pin on the pt2399 should i be getting the clean signal?  i audio probed the thing and there is no clean signal at any pin...or delayed for that matter...