smoking eclipse irfz's

[xeclipse]

Hi guys,
am in possesion of eclipse E404M car amp,(4*40 W rms).It smoked 4 irfz34 power supply transistors,i replaced the 4 irf's and it smoked them again!
What could be the other problem in this amp?Could there be a suitable equivalent replacement for the irfz34?
Regards,Xeclipse.

[xeclipse]

i forgot to mention,the first burnout was caused by a short to the output;there was no load in the second.
Regards

[1moreamp]

You may have only repaired a symptom of a larger issue like a blown channel or what not.
Also the gate lead drivers for the IRFZ's might be damaged by the first failure. I have even seen the PWM chip be damaged and need replacing but this is not as often as the drivers for the gates going south with the mosfets.

Lots of possibilities involved here...hope this helps guide you some...


Sounds like a blown channel with your second posting...

[Perry Babin]

Did the new FETs fail instantly?

Were they clamped to the heatsink?

Did you check the output transistors?

[xeclipse]

hi guys,
1moreamp,thanks for the info.I got a question:when a channel blows,does it blow the output trans plus the op amp?
Perry Babin,
when i connected to power,the protection led turned on and the FETs fried themselves.They were not clamped to the heatsink.
The output trans are 2sa1909 & 2sc5101,i haven't checked them yet.
Regards

[Perry Babin]

Can you post a photo of the inside of the amp?

[xeclipse]

hi Perry Babin,
i am away from home now and wont be back till next week.I'll post as soon as i get back.

[1moreamp]

Originally Posted by xeclipse

hi guys,
1moreamp,thanks for the info.I got a question:when a channel blows,does it blow the output trans plus the op amp?
Perry Babin,
when i connected to power,the protection led turned on and the FETs fried themselves.They were not clamped to the heatsink.
The output trans are 2sa1909 & 2sc5101,i haven't checked them yet.
Regards

Both Perry and I will say the same thing " You have to clamp the amp back down to the sink before you apply any power to it for testing" The only way to avoid this step is to use a current controlled power supply and or a limiter inline of the 12 volt supply. A limit of about 2 amps is probably OK, but even this is risky.

As for the possibility of a blown op-amp driver , well yes this also can happen.

Also ohm out the outputs also as they are highly suspect at this time.

Plz post a pic when you get back and have time....