Hey guys. Would like some insite in help troubleshooting this Alpine amp. I purchased this amp a number of months ago for cheap. The amp was inop and found with the help of Perry Babin i found that half of the output stage mosfets where blown. I got around to ordering new fets and replaced them only to find out that once powered and driving a sub that after a set input volume the amp would begin to ocsilate. I have the the amp apart after trying to see if i could troubleshoot the amp on the bench. But I cant seem to get a output wave form anything like it should. Im using a 4ohm 250Watt load to simulate the sub, a DC power supply only rated to 15 amps though and a sig gen and O-scope.
When i had this powered up on the bench after about 1.5v PkPk signal in something inside the amp would start to "sing" possibly something to do with the switiching PS? Before with no load I could get almost a full 64V PkPk signal on the output of the amp. I didnt do this for long as I wasnt sure if it would fry the output fets. I know a ok amount about electronics. But when it comes to this im at a lose. Im more on the RF side of electronics. I can post pics of said board if need be and I have a manuel for a MRP M850 to kinda help me. I cant find one for the M650.
When i had this powered up on the bench after about 1.5v PkPk signal in something inside the amp would start to "sing" possibly something to do with the switiching PS? Before with no load I could get almost a full 64V PkPk signal on the output of the amp. I didnt do this for long as I wasnt sure if it would fry the output fets. I know a ok amount about electronics. But when it comes to this im at a lose. Im more on the RF side of electronics. I can post pics of said board if need be and I have a manuel for a MRP M850 to kinda help me. I cant find one for the M650.
I see that the images are a little cut off. The no load is right around the input frequecy and the loaded is not even close. Also the spikes in the first image where up to around 102Vpp. I can get a little vid if needed to show what happens when that happens. The power supply pegs 15amps and the amp will "sing" when that happens.
http://vid644.photobucket.com/album...obile Uploads/20141230_135144_zpsjdflkf1a.mp4
http://vid644.photobucket.com/album...obile Uploads/20141230_134859_zpsdib4ivna.mp4
http://vid644.photobucket.com/album...obile Uploads/20141230_135114_zpsqswpdt2w.mp4
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The first video is loaded on the speaker output. I hit maybe 2Vpp on the input is all. Gain was nominal, And bass boost was at 0. Second video nothing much really happened, Unloaded. 3rd you should here it "sing" as i increas the input voltage about .2v steps. and the two pics are one at the output of the powerside of the fet and the other is unloaded and looks to be what it should look like at full power. I can get the amp to pull any more that like 8amps before it gets crazy on the switcher side and goes in protect mode. I would think for my skill set maybe its too far for me to troublshoot?
http://vid644.photobucket.com/album...obile Uploads/20141230_134859_zpsdib4ivna.mp4
http://vid644.photobucket.com/album...obile Uploads/20141230_135114_zpsqswpdt2w.mp4
The first video is loaded on the speaker output. I hit maybe 2Vpp on the input is all. Gain was nominal, And bass boost was at 0. Second video nothing much really happened, Unloaded. 3rd you should here it "sing" as i increas the input voltage about .2v steps. and the two pics are one at the output of the powerside of the fet and the other is unloaded and looks to be what it should look like at full power. I can get the amp to pull any more that like 8amps before it gets crazy on the switcher side and goes in protect mode. I would think for my skill set maybe its too far for me to troublshoot?
I know this is an old thread, but I figured I would give it a shot anyway... I have one of these amplifiers I am trying to repair and I have had strange things happen. I made the mistake of taking it apart a couple of years ago and while it looks new and I have all of the parts, I lost a couple output FETs I took out for what ever reason.
I was bored one night and so I popped open to have a look. I purchased the SM from PacParts and set of measuring voltages. What I found was the PS FETs had 4.6v on the gate legs, 14v on the drain and 0 volts on source. To make a long story short I found a MURS120 diode that was shorted and with the last 3 FETs out of the circuit most of the other voltages checked out against the SM. I measured the HI and LO on the IR2010S and most of the pins were normal except pins 6,7,8 were supposed to have + volts but measured -20v.
Thinking something else was wrong I decided to replace all of the output FETs as well as the shorted diode however now when I power the amp it seems like it goes into protection. I hooked my O-scope to one of the gates of a PS FET and a distorted square wave tries to build then flat-line. Before I put all of the output FETs back in, I would get the +/- 15v on the dual diodes, etc. now i get nothing. I'm just looking to get this thing running so I can learn so any help would be appreciated.
I was bored one night and so I popped open to have a look. I purchased the SM from PacParts and set of measuring voltages. What I found was the PS FETs had 4.6v on the gate legs, 14v on the drain and 0 volts on source. To make a long story short I found a MURS120 diode that was shorted and with the last 3 FETs out of the circuit most of the other voltages checked out against the SM. I measured the HI and LO on the IR2010S and most of the pins were normal except pins 6,7,8 were supposed to have + volts but measured -20v.
Thinking something else was wrong I decided to replace all of the output FETs as well as the shorted diode however now when I power the amp it seems like it goes into protection. I hooked my O-scope to one of the gates of a PS FET and a distorted square wave tries to build then flat-line. Before I put all of the output FETs back in, I would get the +/- 15v on the dual diodes, etc. now i get nothing. I'm just looking to get this thing running so I can learn so any help would be appreciated.
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