Hifonics BRZ2400.1D

[rhempz01]

I have a friend hifonics I told him I would look at and since I'm stuggling with other amps at the moment I took a break from them. I thought this was just a power supply issue. But one half of the output are reading a short? But as I'm taking them out they are all testing fine? Next I'll test the pulldown/gate resistors. Anyone seen this or know what it is?

 

[Perry Babin]

Outputs on the other side can make all with the same part number appear shorted.

 

[rhempz01]

Found it perry, just happened to be the very last transistor I pulled, a capacitor shorted to the casing taking down the output which brought down the power supply. I removed everything burnt or shorted and replace the gate driver transistors and gate resistors. Got it up and running.

 

[rhempz01]

Suitable replacement resistor

Both resistors I ordered one was 5watt the other is 10watt. One is small the other large wirewound resistor. Do u know where I can find just this type of resistor?

 

[Perry Babin]

This is NOT the value you need but I ordered these for a similar amp/application. If the size it right, buy the 6.8k that you appear to have.

667-ERG-3SJ392 (mouser)

 

[rhempz01]

That's exactly what I needed perry thanks. The 6.8k I received are very enlongated, I could make them work but I rather it look OEM. Thanks.

 

[rhempz01]

So is 5watts enough perry? I do have these

 

[Perry Babin]

Yes. The originals are 2 or 3w.

 

[rhempz01]

Ok thanks.

 

[rhempz01]

Everything seems fine without the recifiers installed as soon as I added the rail voltage to the curcuit it drew current.

 

[Perry Babin]

How much current? << very important.

 

[rhempz01]

5amps.

 

[Perry Babin]

5 amps is maybe a bit more than expected. Does it produce audio?

 

[rhempz01]

i shut it off thinking there was a problem somewhere in the output section. Ill check it

 

[Perry Babin]

Be careful and monitor the temperature of all heatsink-mounted components.

 

[rhempz01]

Found some of the pchannel transistors to be leaking. I'm just going to replace the entire section. I'll reposgnon the outcome.

 

[Perry Babin]

I've found a very high failure rate for output FETs in class D amps when they were in the amp when it failed. Many check OK but fail when the amp is driven hard. Sometimes they even fail at low power. Most output FETs are inexpensive and it's not worth risking the amp failing again (which could cause extensive damage if the supply fails).

 

[rhempz01]

Ok so I removed the damaged output transistors. And used a test set I had that tested good to see what happens before I replace all the transistors. The driver card is shown. One side of the pchannel transistors are getting very hot quickly.

 

[rhempz01]

These two are very hot the rest get hot in seconds.

 

[rhempz01]

All the voltages seem ok at the regulators. I do have the correct ratio? 5 p channel and 5n channel correct? Is there a way for me to check the drive with the output transistors out of curcuit?