Blown HIFONICS BXi-1600D (HIP4080AIPZ inside)

[AndreyK]

Hi everyone,
I am new to this forum as like as to Class D. But anyway, need some help.
Several months ago got blown Hifonics bxi1600d for reasonable price and just some weeks ago started to find the problem.

Firstly, after opening it, I found power supply's MOSFETs blown (many of them were just broken in halves, many had blown legs). Of course, there was just continuous current drain through the amp and nothing else. Fuses were good.
Replaced all 12 of mosfets with irf1404 and tried to check it. Nothing happened, but this time the TL494 was just trying to start as soon as the supply voltage was just over 8V. Seemed like there was a short somewhere in the amplifying section.

Got all 12 IRF3710's off the pcb, and found 2 of them shorted: one from Drain to Source and another one from Gate to Source. Replaced them. The amp was still in protection mode (red led). Tried to change the HIP4080AIPZ with new one and nothing happened.

What I have now:
1. Power supply is absolutely Ok. Mosfets are cold at 2Amps without any heatsink.
2. When all the IRF3710s and the HIP are out of the board, the green led is shining just like the AMP is ready. The voltage on big caps never exceeds +/-79.5V, current drain is about 1.7A at 14V and voltage between HIP's 4 and 15-16 pins is slightly over 13V.
3. When all mosfets are at their places, and the HIP is out of the board, the green led shines again.
4. When I put the HIP into the socket, the AMP goes to protection mode. The current is 1.8 to 1.9Amps and almost nothing is hot. The supply voltage of the HIP is again about 13V. The 1st pin have about 12.8V, the 10th has almost 80V - is this normal? At 3th pin there is also about 13V, looks like the AMP disables the HIP all the time.
5. When I put 3th leg of HIP out of the socket, the green LED starts shining, but there is no sound at the output.

What should I inspect else to get closer to solving this problem?
Know here is enough of them who has the experience in this kind of amps, especially based on HIP4080. So very hope on your help.
P.S. And sorry for my English, it's a little hard to describe all the situation just like it is.

[AndreyK]

Can anybody help with my amp? There are almost all main components seem to be good right now, but the protection mode is still shining.. What to try?

[savu]

Disconnect the power amp section. just leave the smps part without anything tied to the output.
it seems that the class d amp is fried also

[AndreyK]

Originally Posted by savu

Disconnect the power amp section. just leave the smps part without anything tied to the output.
it seems that the class d amp is fried also

The smps is working without any problem. Probably yes, there is a problem in amplifying section, but how can I find it out? Again, the HIP4080 is new from intersil and should not be fake (I hope).
Any more suggestions?

[savu]

verify the mosfets diodes and other semiconductors in the amp section

[AndreyK]

Just checked mosfets and dual diodes at supply again, all are OK. The supply voltage is stable, no heat dissipation from output mosfets at all. Still unsure about the HIP - how can I check its working condition?

[savu]

if you have an oscilloscope, try to see the signal that goes from the IC to the gates of the power mosfets.
also check the comparator that feeds the HIP with signal.
sorry for the late replies but i am at work

[AndreyK]

There is 0V going to all 4 by 3 mosfets. They are closed. Thats what I see between 6 and 4 pins of HIP (on 1st pic), or about 50-55kHz signal with amplitude of about 8V. Took a photo of some ICs near the HIP. Dont you mean to check the LM393? There are 3 pics of them, how can I check them? Or it is better to change all 3 of them and check the amp? The supply is stable at 13.2V.

[Ouroboros]

Have you checked if any of the MOSFETs in the amplifier output switching stage have got a short-circuit between the gate and either the source or drain?

Also check the same MOSFETs between source and drain. There should be a normal diode drop (0.6 to 0.7V) on N-ch MOSFETs if the source is more +ve than the drain. Easy to check if your multimeter has a 'diode check' function as an option on its resistance ranges.

[AndreyK]

Originally Posted by Ouroboros

Have you checked if any of the MOSFETs in the amplifier output switching stage have got a short-circuit between the gate and either the source or drain?

Also check the same MOSFETs between source and drain. There should be a normal diode drop (0.6 to 0.7V) on N-ch MOSFETs if the source is more +ve than the drain. Easy to check if your multimeter has a 'diode check' function as an option on its resistance ranges.

Yes, I have already checked all 12 mosfets at amp stage (as it was described in my first post), there were 2 bad of them and yes there were both G-S and D-S short circuits, but now they are all OK (replaced).
Diode test was also OK. It seems like the HIP is in "mute" mode, as there is a high level at pin 3.