Replacing IRFZ42 in Alpine 3558 advice needed....(pics)

maxw · 27th June 2005, 10:06 AM

Hi People,
I have never attempted to repair something like this but I would love to get it going....
One of the IRFZ42's on one side has melted. The other side of the amp is fine and they are completely separate (practically dual mono). What I plan to do is get one of these:
http://cgi.ebay.com/ws/eBayISAPI.dll...tem=7523201348
and....

Swap it for the melted one
Clean it all
Measure values on the PCB of the surrounding resistors etc and compare to the good amp to make sure they have not been damaged etc.

Obviously I can use a multimeter etc so any advice? or better ideas or ways of testing it?

maxw · 27th June 2005, 10:09 AM

I assume that this MOSFET is part of the power supply section so I dont need to match it or anything?

Netlist · 27th June 2005, 10:21 AM

Good luck on this one.

I can see various capacitors screaming to be replaced and I wouldn't be surprised you'll find many bad solderings inside as well.

/Hugo

maxw · 27th June 2005, 10:30 AM

Quote:

Originally posted by Netlist
I can see various capacitors screaming to be replaced and I wouldn't be surprised you'll find many bad solderings inside as well.

Why and why???? Just curious

Its an Alpine Juba (very rare/expensive) and has Nichicon and Elna audio capacitors

maxw · 27th June 2005, 10:35 AM

Another pic for good measure.

Netlist · 27th June 2005, 11:09 AM

I can't and won't comment on the qualities of the amp, but even a Rolls needs service.

Look for caps where the plastic has shrunk from the heat. Take them out and measure them.
Why good luck? It looks fairly damaged although cleaning will reduce the ugly sight. Also, without schematic or experience you're on your own in this rats nest.
Anyway, aren’t we fearless amplifier builders?

/Hugo

maxw · 27th June 2005, 12:13 PM

Quote:

Originally posted by Netlist
I can't and won't comment on the qualities of the amp, but even a Rolls needs service.
Look for caps where the plastic has shrunk from the heat. Take them out and measure them.
Why good luck? It looks fairly damaged although cleaning will reduce the ugly sight. Also, without schematic or experience you're on your own in this rats nest.

Cool, thanks.

Quote:

Originally posted by Netlist

Anyway, aren’t we fearless amplifier builders?

YES!

sss · 27th June 2005, 08:26 PM

strange .

only one blown

check em all! and if u power the amp use some precautions like smaller fuse so it wont blow again .

demogorgon · 27th June 2005, 10:10 PM

i know it off topic, but geez, i'm glad my blown alpine dont look like that!

how can you even begin to decide where to begin?
but more of a chalenge, how get to the parts in question?

maxw · 27th June 2005, 10:56 PM

Quote:

Originally posted by demogorgon
how can you even begin to decide where to begin?

Just follow the burnt blackness

Quote:

Originally posted by demogorgon
but more of a chalenge, how get to the parts in question?

Look in my original post, I found a replacement on Ebay

27th June 2005, 08:26 PM	#8
sss diyAudio Member Join Date: Jul 2003 Location: Israel , haifa	strange . only one blown check em all! and if u power the amp use some precautions like smaller fuse so it wont blow again . __________________ if you are not living on the edge you are taking too much space

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27th June 2005, 10:21 AM	#3
Netlist diyAudio Moderator Join Date: Jan 2003	Good luck on this one. I can see various capacitors screaming to be replaced and I wouldn't be surprised you'll find many bad solderings inside as well. /Hugo

27th June 2005, 11:09 AM	#6
Netlist diyAudio Moderator Join Date: Jan 2003	I can't and won't comment on the qualities of the amp, but even a Rolls needs service. Look for caps where the plastic has shrunk from the heat. Take them out and measure them. Why good luck? It looks fairly damaged although cleaning will reduce the ugly sight. Also, without schematic or experience you're on your own in this rats nest. Anyway, aren’t we fearless amplifier builders? /Hugo

27th June 2005, 10:10 PM	#9
demogorgon diyAudio Member Join Date: Jul 2004 Location: Behind you.	i know it off topic, but geez, i'm glad my blown alpine dont look like that! how can you even begin to decide where to begin? but more of a chalenge, how get to the parts in question?

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