Author Topic: No output when engaged

September 13, 2024, 11:08:40 PM
Read 401 times

jd.musicology

  • Newbie
  • *
  • Posts: 3
  • Karma: +0/-0
    • View Profile
Hello 1st time builder here. I have built amplifiers and microphones with great success so I know how to use an iron. I'm going through the setup guide, at step 5 all the voltages check out within tolerance. Step 6 I get the sine source going and adjusted to 2 VAC. When I engage the unit 0 V. I can confirm listening to the audio I hear it then engage the unit, no sound. Voltages at TP1 .999, TP2 .008, TP3 1.002. Any help is appreciated!

September 14, 2024, 12:21:55 PM
Reply #1

JPK

  • Administrator
  • Hero Member
  • *****
  • Posts: 1105
  • Karma: +36/-0
    • View Profile
Do you have the jumper JMP1 inserted ?
Can you report the voltages you get from here?
JPK

September 16, 2024, 09:02:32 PM
Reply #2

jd.musicology

  • Newbie
  • *
  • Posts: 3
  • Karma: +0/-0
    • View Profile
Yes JMP1 is inserted. I'm using Studio One to generate the tone. I can't get it to output 3 VAC. Here are the measurements:
1.1-
  • V+ =+15 to +16VDC,15.95VDC
  • V-  =-15 to -16VDC), -15.92VDC
  • +12V = +11.1 to +12.9VDC, 11.73VDC
  • -12V  = -11.1 to -12.9VDC
-11.83VDC
1.2
TP1, TP2, TP3, TP4, TP11, TP12 = 0VDC  TP1 -0.1mV TP2 0v TP3 0v TP4 -0.6mV
TP11 8.2mV TP12 14.54V

1.3
TP12 goes from 0 to -2.3VDC
Stays at 14.5V
1.4
TP13 goes from -1.8V to +2.8VDC
-1.78 to 2.86VDC
1.5
  • TP4 goes from 0.060VAC to 0.190VAC .22VAC to .037VAC
TP5 goes from +0.35VDC to -1.2VDC -1.5VDC to 342mV DC


September 17, 2024, 10:23:54 AM
Reply #3

JPK

  • Administrator
  • Hero Member
  • *****
  • Posts: 1105
  • Karma: +36/-0
    • View Profile
TP12 14.54V
Does the DC voltage on TP12 goes to 0V when turning the MIX pot CCW to 0?
Check value, direction and solder joints of U22, P3, R90...R94.
JPK

September 17, 2024, 11:19:50 PM
Reply #4

jd.musicology

  • Newbie
  • *
  • Posts: 3
  • Karma: +0/-0
    • View Profile
Found it! I got a little lazy on two of the U22 pins, re-soldered them and everything works now. Sounds great! Thanks for the fix.:):)

September 19, 2024, 10:06:16 AM
Reply #5

JPK

  • Administrator
  • Hero Member
  • *****
  • Posts: 1105
  • Karma: +36/-0
    • View Profile