Chris661 Posted September 6, 2010 Report Share Posted September 6, 2010 hello all, i got a hold of a memphis 4kw mojo mono block. doesnt produce any out puts to speakers. i open it up to find out someone has aready work on it.. 3 mosfets have been change out due to them burning out. as for the rest of them they all show good resistance. amp turn on doesnt go into proect. the rest of the board look in very good shape. any ideas what may be the problem.? thanks -CHRIS http://www.youtube.com/user/EAZYCHRIS?feature=mhee Link to comment Share on other sites More sharing options...
Chris661 Posted September 6, 2010 Author Report Share Posted September 6, 2010 bump anyone http://www.youtube.com/user/EAZYCHRIS?feature=mhee Link to comment Share on other sites More sharing options...
Boon Posted September 7, 2010 Report Share Posted September 7, 2010 Errrrr if only 3 MOSFETs have been changed then whoever repaired it didn't know what they were doing. A properly fixed amp you shouldn't be able to tell it's been repaired because every single FET in that group should have been replaced. Chances are it's still dead, or has problems in the drive circuit. Try Chris @ db-r.com - he's really good with these amps but there's a huge global parts shortage right now and I'm pretty sure he's flat out right now. 10.x volts fo' life! Link to comment Share on other sites More sharing options...
Chris661 Posted September 7, 2010 Author Report Share Posted September 7, 2010 Errrrr if only 3 MOSFETs have been changed then whoever repaired it didn't know what they were doing. A properly fixed amp you shouldn't be able to tell it's been repaired because every single FET in that group should have been replaced. Chances are it's still dead, or has problems in the drive circuit. Try Chris @ db-r.com - he's really good with these amps but there's a huge global parts shortage right now and I'm pretty sure he's flat out right now. thanks for the reply very much. as for as u stated "every single fet should have been change" i am assumin like u said also there are some bad in the line. as it look like they are connected in Series. i will send chris an email thanks again http://www.youtube.com/user/EAZYCHRIS?feature=mhee Link to comment Share on other sites More sharing options...
Boon Posted September 7, 2010 Report Share Posted September 7, 2010 thanks for the reply very much. as for as u stated "every single fet should have been change" i am assumin like u said also there are some bad in the line. as it look like they are connected in Series. i will send chris an email thanks again They're paralleled for load sharing. But yeah, if even 1 is bad (or even just 1 gate resistor) then the amp will either blow up or just not work. 10.x volts fo' life! Link to comment Share on other sites More sharing options...
Chris661 Posted September 7, 2010 Author Report Share Posted September 7, 2010 They're paralleled for load sharing. But yeah, if even 1 is bad (or even just 1 gate resistor) then the amp will either blow up or just not work. yeah, the amp came from a buddy had 3 L7 ran off of it. assuming too low of a ohm load to the amp causing it to blow. so i am hoping it just the fet that need to be replaced. thanks. http://www.youtube.com/user/EAZYCHRIS?feature=mhee Link to comment Share on other sites More sharing options...
Chris661 Posted September 8, 2010 Author Report Share Posted September 8, 2010 story goes, i remove some mosfets, that i assume they dont work because of low resistance. as i removed them. i re-test the resistance again. and what do you know there is no resistance at all. now the question is where can i find/ order these mosfets? thanks much. i have contacted db-r but no reply yet.. http://www.youtube.com/user/EAZYCHRIS?feature=mhee Link to comment Share on other sites More sharing options...
Boon Posted September 8, 2010 Report Share Posted September 8, 2010 What are they? IRFP360LC? You should be checking with the diode test function, by the way. 10.x volts fo' life! Link to comment Share on other sites More sharing options...
Chris661 Posted September 8, 2010 Author Report Share Posted September 8, 2010 No they are IRFP1405 test everyway i can they dead as can be http://www.youtube.com/user/EAZYCHRIS?feature=mhee Link to comment Share on other sites More sharing options...
Boon Posted September 9, 2010 Report Share Posted September 9, 2010 Hrm IRF1405 is from the power supply section. Badass FETs. Are the rest 1405s or are they 3205s? If it's been repaired before it's possible they used 1405's instead since they're rated higher. Allied have them: http://www.alliedelec.com/search/searchresults.aspx?N=0&Ntk=Primary&Ntt=IRF1405 Well, you can order them from there. They don't have any because of a global mosfet shortage. 10.x volts fo' life! Link to comment Share on other sites More sharing options...
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