R18 R23 and TP4 value

[Shaders]

Hello,

I am in the phase of tests of the project Rev C Option 1,



I have a problem whose I am unaware of the source:

• R18 varies TP4 only between 0.15V and 3.45V (in the place of -4 +4)
• R23 does not have any effect.

I have the right values on IC6 and IC5, TP1 = 0.5V.

Somebody did it has already have this kind of problem?
In advance thank you.

Cordially
shaders

[Carl-NC]

R23 should not affect TP4. I believe the newer offset design limits the variation of TP4 from -1.66v to +1.66v, or a total of 3.3v. Sounds like you are getting the right overall movement (3.3v), but not centered about 0v. If you are clocking Q3, try removing the clock by pulling IC5, Q1, or Q2.

- Carl

[Unregistered]

Having recently finished putting together Carl’s HH, I had run into the same problem trying to zero TP4. It might be caused by type of NE5534 used; I don’t know for sure. I finally solved it by lowering R17 to 33K. This gave me plenty of adjustment with R18.
With a follow up note in adjusting R18, I noticed that adjusting either R2 (Frequency) and/or R3 (Pulse Width) did change the voltage on TP4. I had used trimmers for both R2 and R3, so once I set sensitivity vs. power consumption, I went back and set TP4 to 0V, which did seem to improve things somewhat. Good luck.

[Shaders]

thanks