GZPA 1.4000 DXII

[Achim1409]

I don't think, that it is correct, to have the sine wave on the +-5v input for the drive board.. Can someone explain please.. It's also on the +-15v but only if I increase the gain. but only, if I use signal ground. If I use secondary, then it's normal.

 

[Perry Babin]

Did you ever check the value of the filter caps for the high-side B+ of the 21844?

Did you install a feedback resistor on terminals 1 and 2 of the TL072 when you were checking its signals?

Are you using a signal source with a grounded shield?

 

[Achim1409]

You mean this small caps on the driver board? No, i dont. which value should they have?
No feedback resistor mounted. I always use a smartphone as audio signal. At home i have a fequency generator.
I can continue in a week, because again, both drivers are damaged...

 

[Achim1409]

I received the diagram. Fets are correct.

 

[Perry Babin]

With some amps, an ungrounded/floating shield can cause problems.

The caps for the high side have been from 4.7uF to 10uF. 5.6uF and 6.8uF seem to be the most common.

 

[Achim1409]

I checked the caps. One has 4.4uf the other 4.6uf..i think it is OK. Do they have a specific direction?

 

[Perry Babin]

Most are ceramic which aren't polarized. That doesn't apply if they are tantalum or something other than ceramic.