need help on a power acoustic lt1920-2 amp

truckr012001 · 30th October 2008, 06:17 AM

i working on this amp found a couple burnt resistors which im replacing tomorrow and to bad power supply transitors but i dont know what they are these are the numbers on them 1rfz44n i_r 402k 7w 3t can anyone help me and tell me what transistor i need 2 buy 2 replace it and tell me what size fuses should b in the amp it had 4 30amp fuses when he gave it 2 me to work on and i believe they are 2 big

damage · 30th October 2008, 12:55 PM

That first number contains an "I" not a "1".

IRFZ44N or IRFZ44NPBF

either will work.

Perry Babin · 30th October 2008, 02:24 PM

If the transistors failed in only one of the supplies, you need to replace all of them in that power supply. If one failed in each supply, you need to replace all of the IRFZ44s in the amp (12 total?). The power supply components are split down the center of the amp.

Did you check the output transistors (the larger transistors) to determine if any had failed?

Four 20 amp fuses would likely be enough for the amp.

jol50 · 30th October 2008, 05:05 PM

Yes check outputs carefully or when you start it back up the PS will go poof again. I just worked on two 980s, the outputs blew and took out the PS that is very common. Start it on limited power or a tiny fuse is always a good idea. These amps appear over fused to me, this 980 has four 25A fuses.

Having a PS for each channel can be nice, if one is toast the other might be just fine. But if it was bridged, then one channel can affect the other and blow it too. Or if damage was not speaker related, like if a 12v power problem.

truckr012001 · 30th October 2008, 06:31 PM

thanks for the info guys i didnt know i had to replace all of them and yeah i did check them dont believe any of the other ones failed im going to get the parts today ill let u know if it works or not thanks again for the help

jol50 · 30th October 2008, 10:58 PM

When they run in parallel, if one goes it can take none or all the rest with it. Problem is you can't really find out if one is damaged or how much life is left in it. I've found a few amps now that someone stuck part of them in and the other original ones let go. I don't know if they did right away or later, hard to say.

30th October 2008, 06:17 AM	#1
truckr012001 diyAudio Member Join Date: Oct 2008	need help on a power acoustic lt1920-2 amp i working on this amp found a couple burnt resistors which im replacing tomorrow and to bad power supply transitors but i dont know what they are these are the numbers on them 1rfz44n i_r 402k 7w 3t can anyone help me and tell me what transistor i need 2 buy 2 replace it and tell me what size fuses should b in the amp it had 4 30amp fuses when he gave it 2 me to work on and i believe they are 2 big

30th October 2008, 02:24 PM	#3
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	If the transistors failed in only one of the supplies, you need to replace all of them in that power supply. If one failed in each supply, you need to replace all of the IRFZ44s in the amp (12 total?). The power supply components are split down the center of the amp. Did you check the output transistors (the larger transistors) to determine if any had failed? Four 20 amp fuses would likely be enough for the amp. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

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30th October 2008, 12:55 PM	#2
damage diyAudio Member Join Date: May 2006	That first number contains an "I" not a "1". IRFZ44N or IRFZ44NPBF either will work.

30th October 2008, 05:05 PM	#4
jol50 diyAudio Member Join Date: Nov 2007	Yes check outputs carefully or when you start it back up the PS will go poof again. I just worked on two 980s, the outputs blew and took out the PS that is very common. Start it on limited power or a tiny fuse is always a good idea. These amps appear over fused to me, this 980 has four 25A fuses. Having a PS for each channel can be nice, if one is toast the other might be just fine. But if it was bridged, then one channel can affect the other and blow it too. Or if damage was not speaker related, like if a 12v power problem.

30th October 2008, 06:31 PM	#5
truckr012001 diyAudio Member Join Date: Oct 2008	thanks for the info guys i didnt know i had to replace all of them and yeah i did check them dont believe any of the other ones failed im going to get the parts today ill let u know if it works or not thanks again for the help

30th October 2008, 10:58 PM	#6
jol50 diyAudio Member Join Date: Nov 2007	When they run in parallel, if one goes it can take none or all the rest with it. Problem is you can't really find out if one is damaged or how much life is left in it. I've found a few amps now that someone stuck part of them in and the other original ones let go. I don't know if they did right away or later, hard to say.

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