I have brought my mtx 2300 back from the dead but still have some problems. I have biased the amp correctly at 1mv but when i increase the output and a high note hits, the transformer or caps next to it( its hard to tell ) making a arching sound and the amp clips out. The noise kind of follows the beat of the music and some times i get a high pitch noise. Would this be a sign of a bad cap, transformer or something else causing it. I have replaced all the audio fet's , rectifiers, and some resistors that where blown. THe orginal problem was caused by a broken leg in one of the rectifiers and a broken rca jack. I am new to repairing amplifers but do has some electronic background. any help would be great.
Thanks
Dave
Thanks
Dave
What do you mean by 'clips out'?
If you are saying that it shuts down, will the amp shut down or whine if you drive and load only one channel at a time (try both channels)?
If you are saying that it shuts down, will the amp shut down or whine if you drive and load only one channel at a time (try both channels)?
I tried with one and both channels hooked up. Once the amps draws about 7 to 8 amps the arcing noise starts speakers distort and any more current beyond That it will shuts down until the input volume is reduced. It does seem to happen sooner on the right then the left channel.
When driving a single channel, do you have to drive a stronger signal into it to make it shut down or does it start to shut down at the same point regardless of whether you have one or two channels driven?
Is it always at the 7-8 amp range no matter how you have the two channels loaded?
What is the current capacity of the 12v power supply?
Is it always at the 7-8 amp range no matter how you have the two channels loaded?
What is the current capacity of the 12v power supply?
When I play music and it hits a high note or a low frequency. It causes the problem but this is all depends on what the volume is set for. The power supply I have is rated for 13 amps 15 inrush. I had the same problem when It was installed in the car. I will see if I can get a video made. Just let me know where you would want me to take voltage readings so I can include it
Don't make a video for me. I won't watch it. Someone may use it.
You need to use a sine wave (test tone) for better consistency.
You need to use a sine wave (test tone) for better consistency.
I don't have enough information yet. I'm not 100% certain that I'll be able to determine what the problem is. It's not a straightforward problem.
You can find test tones on the following page/link. Use the 100Hz.
Index of /temp/test tones
You can find test tones on the following page/link. Use the 100Hz.
Index of /temp/test tones
Hi Perry,
So i ran the 100hz, it sounds clear until i turn the gain half way up, then it starts to distort and then transformer starts making an arching sound. This is around 7 amps with both channels running , 4amp with just one channel . If i i go above that point the amp shuts off .
So i ran the 100hz, it sounds clear until i turn the gain half way up, then it starts to distort and then transformer starts making an arching sound. This is around 7 amps with both channels running , 4amp with just one channel . If i i go above that point the amp shuts off .
So is the level the problem or is the position of the gain control the problem? You have to reduce the number of variables to the lowest number when you're troubleshooting.
It happens when I increase the volume or the gain. I set my bias from r97 to 3rd leg of fet6 and r155 to 3rd leg of fet18. All set to .001. The amp sounds great at low volumes .
To get the amp working from original dead status I replaced all the fets except ones in the power supply (fet9 to12) , rect 1 &2, r189, c91, c90, r150, r150, c86 and all the a42's one the board (one was bad had a bunch so replaced all of the)
To get the amp working from original dead status I replaced all the fets except ones in the power supply (fet9 to12) , rect 1 &2, r189, c91, c90, r150, r150, c86 and all the a42's one the board (one was bad had a bunch so replaced all of the)
This amp may be like the Rockford amps that are sensitive to the output transistors used. What is the exact, complete part number of the output transistors you used?
Do you still have the old transistors?
The540N causes similar problems in some of the Rockford amplifiers. I'd try reinstalling the old ones (one channel at a time, since you probably don't have enough good ones) to see if the amp will work properly.
If so, order either the IRF540PBF or the IRF3415. I use the IRF3415 in all that come in for repair now. Since the amp may be finicky, I'd suggest that you order both if the old FETs allow both channels to work properly.
Don't operate either channel with no FETs in it. Just drive the channel with the old FETs if you still have them.
The540N causes similar problems in some of the Rockford amplifiers. I'd try reinstalling the old ones (one channel at a time, since you probably don't have enough good ones) to see if the amp will work properly.
If so, order either the IRF540PBF or the IRF3415. I use the IRF3415 in all that come in for repair now. Since the amp may be finicky, I'd suggest that you order both if the old FETs allow both channels to work properly.
Don't operate either channel with no FETs in it. Just drive the channel with the old FETs if you still have them.
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