Car Amplifier Repair

[HaRuMaN]

My Rockford Fosgate Punch 200.2 amp has a burned out chip of some sort.  This was written on it, before it burned:

Code: [Select]


MT    P7
5NO5HD
      810


What is it and where can I find a replacement for it??

[whammoed]

Its a transistor of some kind.  Maybe a mosfet power transistor?
5NO5HD looks like the manufacturer part number and I can't find any info on it.  I'm sure you could get the part a www.mouser.com if you could properly cross reference it to another mfg.  Google for 5NO5HD and you will find a couple places that will give you a quote for that part...who knows about minimum order and such though.

[whammoed]

Also might help to post here:
http://www.diyaudio.com/forums/forumdisplay.php?s=&forumid=38

[Stingray]

Yeah, not a chip. Just a transistor of some kind. If you're feeling really lucky you might be able to find one at Radio Shack Cell Phone Shack.

-S

[ChadTower]

Get the schematic / parts list and that will tell you exactly what part that is.

[JCL]

My Rockford Fosgate Punch 200.2 amp has a burned out chip of some sort.

[ChadTower]

Just get the schematic and look up Q7.

[JCL]

A quick google search makes me think the part is a MTP75N05HD. This is a power transistor that could easily be used for high power amplifier work.

So look up MTP75N05HD on google and try to find a source or an equivalent.

Mouser electronics may have an equivalent:

http://www.mouser.com/index.cfm?&handler=data.listcategory&D=*MTP75N05HD*&terms=MTP75N05HD+&Ntt=*MTP75N05HD*&Dk=1&Ns=SField&N=0&crc=true

[HaRuMaN]

Thanks everyone for the help.  JCL, that Mouser link is just what I needed! 

[JCL]

Thanks everyone for the help.

[HaRuMaN]

Well, this amp was a gift to me...  not working when I got it, so I'm not sure.  I looked up info on both transistors, they are definately compatable.  Now I have a new problem.  I replaced the burnt one and hooked it back up to a power supply, and immediately the replacement began smoking.  I turned off the power before any damage was done (I think) and now I'm wondering where do I go from here?  Anyone know about these things or have any ideas??  Help??   

[JCL]

This is now officially more complicated. And much harder to debug without experience and without a schematic.

The transistor fried because too much current went through it. Given the type of transistor, this is likely the output transistor. This is the one that drives the speaker.

Was there an appropriate load on the output?

If the output was shorted or way too low impedance, this could occur. Depending on the type of amp, having no load (no speaker) could also cause the output to overheat. Assuming you had a speaker attached, did it make any noise before you shut it down?

Depending on how the output works, a (non-obvious) failure in one of the other transistors could cause the new one to fail (on if the smoke came out, it's probably dead or critically injured).


The other possibility is that the input to this transistor was incorrect. This would indicate a problem further "upstream" from this transistor. Figuring this out is more difficult and I can't give specific pointers without knowing more about the amp. Very oversimplified, the most likely problem is that the DC bias to the output transistor is incorrect.

This might be a better question for a car audio forum.