Just bought one of these with at least a blown power supply and I was wondering if anybody might know what type of power supply fets,gate resistors for the power supply fets,and power supply driver transistors this amp uses. I'd like to get parts on the way before the amp gets here if I could so I can fix her up real quick. Thanks.
This type of amp (clone that many manufacturers use) began using IRFZ44s then changed to IRFZ46s. Both use 100 ohm gate resistors. The driver transistors rarely fail but they are KTA1023s and KTC1027s.
I'd also suggest that you order IRFB31N20Ds (outputs) and MPSW42s (drivers for the outputs - which need to be replaced regardless of the condition of the outputs).
I'd also suggest that you order IRFB31N20Ds (outputs) and MPSW42s (drivers for the outputs - which need to be replaced regardless of the condition of the outputs).
I've been using the BD139 and BD140. Steve Mantz stated that he had some in stock. He may sell you what you need.
http://www.diyaudio.com/forums/car-audio/182053-memphis-mojo-16-mcd4kw-2.html#post2455845
http://www.diyaudio.com/forums/car-audio/182053-memphis-mojo-16-mcd4kw-2.html#post2455845
www.taydaelectronics.com
Not the most legit looking site but the guy who originally posted the link said he had used the parts and they worked in an Orion 2500d .
Not the most legit looking site but the guy who originally posted the link said he had used the parts and they worked in an Orion 2500d .
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Well this amp finally showed up. Power supply and output fets are both shorted . The inductor close to the rectifier had a small short in it which I was able to isolate. So far I have only removed the power supply fets and gate resistors. I noticed in the power supply there are four sets of two diodes. One looks to be about half watt and one looks to be one watt. Does anyone know what these are and if they typically fail when the fets fail? They seem ok but I may replace them just to be sure. I have some power supply drivers on the way but I am hoping the ones in the amp are still good as those parts are about a week away yet.
If they're the ones that I suspect that you're referring to, they are supposed to be a clamp for voltage spikes on the primary square wave. I say 'supposed to be' because it's poorly implemented and can't really work as they should. Rockford uses this type of circuit but the ones in their amp can work as they should.
This question is for Perry. I think while I was reading through the tutorial last night I read that you suggested replacing the mpsa92's on the driver card as well as Q124 and Q125 . I am wondering if it is all right to replace the mpsa92's with mpsw92's ? It would keep me from having to order more parts.
I've replaced all PS and output fets and their gate resistors. I replaced Q124 and Q125 on the driver card with MPSW42s and mounted them so they are closer to the fan. I also repaired the shorted common mode choke inductor. The amp powers up fine through a 10 amp fuse. Fan needs to be lubed or replaced as it makes a horrible noise. The amp will produce clean audio at a low level but when I checked out the power supply waveform with my scope this is what I have :
Does this look right? Looks Iffy to me. I should also note that I only have ~2.3 volts dc on the gate leg of each of the fets. Is that a bit too low? Do I have a bad power supply driver transistor or possibly a bad power supply controller IC?
Does this look right? Looks Iffy to me. I should also note that I only have ~2.3 volts dc on the gate leg of each of the fets. Is that a bit too low? Do I have a bad power supply driver transistor or possibly a bad power supply controller IC?
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