PT80 problems (wierd voltages)

[Michael Allen]

I've put this together with the MAX1044 and it's not working at all. If none of the ICS are in, the MAX1044 successfully delivers 16v to the voltage regulators (~8.9V input). The NE571 and TL072 get ~11.5V and the PT2399 gets 4.93V.

Now,

If I put in any one of the ICS, the circuit goes haywire and the voltage drops ridiculously. The input voltage from the power supply (measured at the input jack) oscillates between 0 and 3.9V and the output of the MAX1044 hangs around 7.2v. So the PT2399 gets around 3.7v, the NE571 and TL072 only get around 5v since the 12v regulator can't work. So, it doesn't matter whether its the TL072, the PT2399, or the NE571 inserted, the outcome is the same. It's like the power supply is getting shorted somehow, but all the way back through the MAX1044. I've tried about 10 different MAX1044s, I don't know what's going on here. The charge pump works if no IC is inserted.

With the ICs inserted, the TLO72 has relatively correct voltages. With pin8 at 3v, the other pins get half that so I know the voltage divider is working. Pin 4 is grounded.

PT2399
1. 3.0v
2. 1.51-53
3. 0
4. 0
5. 1.75-77
6. 1.5
7. 2.83-86
8. 2.83-85
9. 1.34-39
10. .1
11. .1
12. 1.42-45
13. 3
14. 1.60-64
15. 1.52-54
16. 1.52-55

NE571
1. .6 then down to 0 and back to hold at .3
2. .54
3. .54
4. 0
5. .68
6. 2.4
7. 2.3
8. .2
9. .2
10. 2.3
11. .63
12. .63
13. 3
14. .53
15. .53
16. .3

Audibly, there is no delay since no signal is coming out of NE571 pin 10 to the PT2399. The signal is really distorted since the opamp is not receiving proper voltage.

Any ideas? All part values are correct and I have found no solder bridges, broken traces, etc.

[miqbal]

How about if you bypass all the charge pump+78L12 circuitry (but keep the the 78L05) and try the 9V directly? Still no delay?

[Michael Allen]

Nope, if i do that the power seems to fade in and out...

[miqbal]

Ok, if you suspect for short on the power rail, then...

How if you put ONLY the MAX1044?

Here is my readings WITH ONLY the MAX:

Voltage source is 7.91V (drops to 7.88V),
the chargepump delivers 13.45V,
78L12 output= 11.87
78L05 output= 4.99V


tl072   
1= 0
2= 0
3= 5,92
4= 0
5= 2,91
6= 0
7= 0
8= 11,87

pt2399   
1= 4,99
2= 0
3= 0
4= 0
5= 0
6= 0
7= 0
8= 0
9= 0
10= 0
11= 0
12= 0
13= 0
14= 0
15= 0
16= 0

NE570
1= 0
2= 0
3= 0
4= 0
5= 0
6= 0
7= 0
8= 0
9= 0
10= 0
11= 0
12= 0
13= 11,87
14= 0
15= 0
16= 0

On some pins of the IC (23999 and NE570), I found some  small reading for a moment, but then drops to zero.

[Michael Allen]

Fixed it!

When I bought parts for this project I ordered box 1uF's that were enormous! They had short leads so i had to solder clipped resistor leads to them and bend them into the holes. So I have a lot of big caps sticking off the board. Anyways, I just re-soldered all of the leads to the caps and now she's working.

Thanks miqbal for posting your voltages!