Audiopipe protection aqx-360.4

[Albis2985]

I took all the outputs and they all measure well the protection is entering through pin16, someone has a scheme since the amplifier sometimes turns on well without any problem and other times it turns on and off immediately the problem is intermittent I don't know what exactly the protection is who is jumping if it is the preamp stage or the amplification stage

 

[Perry Babin]

Post a photo of the component side of the main board and the component side of any driver boards in the amp.

 

[Albis2985]

Well for the moment I will not have pictures since the phone broke down, as soon as I have something to take the pictures I will post them

 

[Perry Babin]

I don't know how good your camera phone is but you (all here) should look for a good used older model Nikon Coolpix camera. People will give them away. You can buy them for dirt cheap on ebay. They will typically take better photos than the average phone, often due to the better flash and the ability to zoom.
bcae1.com - Car Amplifier Repair Tutorial - The Basics

 

[Albis2985]

If Perry already ordered a camera on eBay, but for now I think that the photos will not be necessary yesterday, I was reviewing and analyzing the circuit a little, I discovered that before the amplifier turned off completely, two outputs gave DC voltage. I removed the transistors from those two outputs and the amplifier turned on well. I have checked the components and they all measure the suspicion of the 649a and 669a polarization transistors, although they are measured well as those of the outputs, I will exchange transistors to see what causes problems and then notify you on the fly

 

[Albis2985]

Good afternoon Perry, the problem with this amplifier is that Q262,263,264 and 265 when turning on the amplifier marks a voltage of more or less 27volts at the base and that is why the amplifier is protected, the damage is intermittent after several times the amplifier works well and the output behaves the same as the others marks a voltage of plus or minus 7 volts in its probe base all the complementary transistors in that section even change the b649 and b669 the problem continues you recommend me to change all the transistors of that output because inside and out of the circuit they measure well even with my tester, or do you think the problem is in the protection part?

 

[Perry Babin]

Does the input to that channel have significant DC at the input to the power amplifier stage (at the input to the differential amplifier)?

 

[Albis2985]

I do not understand exactly your question I attached an image of the stage of the amplifier in question

 

[Perry Babin]

Do this by process of elimination.

Remove the drivers.

Does it have DC on the output of the amp?

If not, reinstall the drivers and remove the previous stage of transistors.

Again, do you have DC on the output?

 

[Albis2985]

ok do i do all this with the output transistors installed or do i do it without the output transistors?

 

[Perry Babin]

You have all of the outputs in the circuit. You have only one stage of transistors out at a time.