Tonepad reboot no sound

Started by Lizard King, November 11, 2013, 08:33:52 AM

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Lizard King

I'm just about ready to give up building projects....I must be too stupid to live - nothing ever seems to work.

I etched my own board and it looked almost identical to the pdf from Tonepad.  The only mod was a 24K resistor in place of the 33K in the level control circuit.

I built the board and I get no output.  I cleaned up a few traces and still nothing.

Voltages: IC1
8   5V
7   2.55V
6    3mV
5    10mV
4     0
3   2.5V
2   0.72V
8  0.74V
9 - 16  2.5V

IC2
1  8.   10V
2  7.    3mV
3  6.    26mV (climbing)
4  5.    4.8V
5  4.    0
6  3.    4.98V
7  2.    .3V
8  1.    .2V (dropping)

I had to hurry the voltage readings as I noticed the 78L05 getting EXTREMELY hot so I shut it down before it popped.

Any suggestions - other than to get a new hobby?  I hear coin collecting is easy....


duck_arse

can you post a circuit diagram? you would be looking for a short around the pt2399, it can't draw that much current, surely. it not mentioned in the princetin "spec" sheet. if your ic2 is a dual opamp, you seem to have v/2 on pin4, instead of 0V, and 10V on an input instead of pin 8. backwards, maybe?
don't make me draw another line.

Lizard King

#2
D'OH...using a TL072 from the Tonepad layout.  The IC is "upside down" to me so I numbered the pins backwards......maybe dyslexia explains my problems....

http://tonepad.com/getFile.asp?id=98

I'll look for a short around the 2399, thanks.  I originally had a short between the 510K & 240K resistors in the input circuit that was giving me some crazy infinite feedback so I know something is going on.  When I fixed that everything dropped out, even the infinite feedback.