Rockseries 3000w gate output waveform

[joselorenzo]

Hello
Someone in the forum has repaired or has a way to help me with a ROCKSERIES 3000w amplifier.
I have doubts about the correct and good waveform in output transistors .

I get in the gate pin transistor IRFP260N mosfet

 

[Perry Babin]

Please read the 'best initial settings' section on page 73 of my car audio site.

You have to center the trace before looking at the signal.

Use the ground position in the coupling switch to set the trace.

Use DC coupling when viewing/photographing the waveform.

Set the timebase so that you have about 3-4 cycles displayed.

Why are you questioning the signal you see?

 

[Osvaldo de Banfield]

Rise time is clearly bad. Check drivers and resistors or diodes in the gate-driver path.

 

[Perry Babin]

#3:
In some amps, they use a parallel resistor/diode to induce deadtime. I don't know if that's true for this amp.

joselorenzo :
Can you post a couple of good quality photos (in focus, no flare from the flash...) of the areas indicated in the attached photo?

 

[joselorenzo]

The amplifier I have tried to repair twice.

Now this last attempt changes
U9, U11, Q3, Q4, Q6, Q7, Q8 and Q9.
All IRFP260N are also new.
I have doubts with the waveform because I have no experience in this amplifier design

EDIT : I have problems uploading pictures

 

[joselorenzo]

More pictures

 

[Perry Babin]

After looking at the drive circuit, I'd suspect the NPN driver transistor (DK) but check the components listed in post #3.

The attached image is more what I'd expect. It was taken with the rectifiers removed from the amp.

 

[joselorenzo]

I try to upload more photos but the high resolution does not allow me

 

[Perry Babin]

I think I have a similar amp that I can repair to check the waveforms but if you get it repaired, post it so I don't have to fix that amp.

 

[joselorenzo]

I think I have a similar amp that I can repair to check the waveforms but if you get it repaired, post it so I don't have to fix that amp.

I'll wait until I can compare the waveforms by getting another similar amplifier or with help from you or some other forum member.

Any advance I do know
Thank you

 

[Perry Babin]

Note timebase and vertical amplifier setting for each.

Mouseover for descriptive file names.

Q10 = Q4

 

[joselorenzo]

There is a lot of similarity in waveforms.
It's time to test the operation of the amplifier

I appreciate your time and help in the subject
regards

 

[Perry Babin]

The ones above are similar but the output drive (as was previously stated in post #3) doesn't look good. I suspect that the NPN driver transistor is defective. Remove it and check it.

 

[joselorenzo]

I had installed all new transistors drivers.

Again I changed DK transistor.

I upload images of the waveforms in the gate terminals of the output transistors audio.
I do not see any change

 

[Perry Babin]

What do the base and emitter waveforms on the DK and the base of the AG transistors look like?

 

[Perry Babin]

see also 15.

Are you using the exact replacement outputs from a reputable distributor?

What does the gate on the high-side look like?

What's the timebase setting on your scope?

 

[joselorenzo]

What do the base and emitter waveforms on the DK and the base of the AG transistors look like?
I upload pictures of the waveforms of DK and AG LOW SIDE AND HIGH SIDE.
Are you using the exact replacement outputs from a reputable distributor?
Verical and lcsc.com
What does the gate on the high-side look like?
I upload pictures
What's the timebase setting on your scope?
In all the recent measurements with photography Time/Div 2us

 

[joselorenzo]

The following measurements with photography are from the AG and DK transistors on the high side
And the gate waveform output transitor

 

[Perry Babin]

Is the var sweep control fully clockwise on your scope?

Unless you have two probes and you use your scope in differential mode with DC coupling, I think you're going to have to remove the rectifiers to get usable high side waveforms. The waveforms I posted that show the partial face of the scope were all taken with no rectifiers. These are the low side.

Q12 is the NPN driver. Q14 is the PNP driver. The emitters of both are directly connected so only one photo is needed.

Did you buy these FETs from verical or lcsc? I don't see lcsc as being authorized by any semiconductor manufacturer.