Tech Note 343 Detail

No output.

Affected Products:

PI-9598 Student Function Generator/Amplifier

No output appears from the function generator when the unit is turned on.

PASCO Solution:
The most likely reason is damage to the output amplifier. To verify that this is the problem, turn on the unit, increase the amplitude, and check for an output signal at U4 pin1. If the signal is missing, then please contact customer service [(800)-772-8700 x 78] to return the unit, referencing this tech note.

If the signal is present, then the output circuit needs to be replaced, which consists of the following chips: U4 (430-095), Q1 (420-002), and Q2 (420-003).
After replacing the output op amp, you will need to calibrate the bias current of the output amplifier:

  1. Set the output amplitude to minimum.
  2. Set the output frequency to 5 kHz.
  3. Adjust R32, the blue pot that is closest to TP3 and above U4, until you obtain a a reading of 0.017 - 0.035 V across TP3 and TP4 (located to the right of U4).

Creation Date: 07/17/2002
Last Modified: 04/11/2003
Mod Summary: