I have here a BD1000@1 amplifier from Rockford, I replace all the fets in the PS as one of them was chipped and exposed the die inside. I had to use IRF3205's due to the originals are now obsolete.
The filter cap on the output (4.75uf 250v) was falling off the board, one pin had broken, so I went ahead and fixed that by soldering the small short pin it had left over.
I also had to replace the RCA jack because the ground pins had broken off the RCA housing.
Well upon testing (amplifier in chassis of course) I get output but there is a bad reverb in it...sounds almost like a basketball bouncing on wood floor (springy). The output looks clean on the scope, am using a 10" 4ohm subwoofer in a sealed enclosure. I did get full power 44vAC at one point when the output was clean, now it just sounds bad...
There is also a turn on and off pop upon power up and down.
Any help is greatly appreciated.
The filter cap on the output (4.75uf 250v) was falling off the board, one pin had broken, so I went ahead and fixed that by soldering the small short pin it had left over.
I also had to replace the RCA jack because the ground pins had broken off the RCA housing.
Well upon testing (amplifier in chassis of course) I get output but there is a bad reverb in it...sounds almost like a basketball bouncing on wood floor (springy). The output looks clean on the scope, am using a 10" 4ohm subwoofer in a sealed enclosure. I did get full power 44vAC at one point when the output was clean, now it just sounds bad...
There is also a turn on and off pop upon power up and down.
Any help is greatly appreciated.
well, i'm gonna take a stab since nobody else has responded yet.... did you test the cap before soldering it back on? if it broke off due to vibration, then it's likely there are other joints on the board that could have broken/gone dry as well. it almost sounds like you are getting feedback from the rail power to the preamp section, but i am unsure. perhaps there is a problem with how the power supply is reacting to the rail voltage. i.e. a small cap gone bad between the rail and the op-amp, or incorrect gate drive voltage or something related to the different fets. what were the originals? original gate resistor values and current resistor values? what is the gate voltage?
I am using a cheap JBL 10" GTI 10 mkII subwoofer and also have dummy loads. Without a load the signal looks clean even with a reactive or non-reactive load the signal looks clean. But the sound is just horrible, sounds bouncy.
Also why am I getting 225watts on the output but the input is only 12amp at 13.5v (162watts) how is that even possible.
I am pretty certain it is not my subwoofer as I hook various other amplifiers and all sound good except this one.
I will post pics of the sine wave with and without load and see if I can post a link to a youtube video so you guys can hear how bad it sounds.
Thanks in advance.
Also why am I getting 225watts on the output but the input is only 12amp at 13.5v (162watts) how is that even possible.
I am pretty certain it is not my subwoofer as I hook various other amplifiers and all sound good except this one.
I will post pics of the sine wave with and without load and see if I can post a link to a youtube video so you guys can hear how bad it sounds.
Thanks in advance.
32vac and 4ohm load, I also verified with a current meter on the speaker wire. Just curious as why the pull on B+ is only 12a.
By the way I did check the signal with the scope on U17 pin 1 and after C74. I used a 60hz sine wave and the signal there appeared pretty fuzzy (I'll post a pic here in a few minutes.)
By the way I did check the signal with the scope on U17 pin 1 and after C74. I used a 60hz sine wave and the signal there appeared pretty fuzzy (I'll post a pic here in a few minutes.)
Here's a link for the youtube video, I have it at very low power so the microphone on the cell phone wouldn't distort and record better detail of the sound am talking about. Sound starts at 10 seconds, this is how it sounds at high volumes as well, amplifier has lots of output power but clearly sounds bad on my 10" sub. Low Pass xover is set at lowest to see if that helps but "bouncy" noise is still there no matter where the LP is set to.
This is what pin 1 of U17 and looks pretty much the same as before or after C74.
Here are the other signals that are shown on the schematics.
Here is how the output looks with the 10" subwoofer.
This is what pin 1 of U17 and looks pretty much the same as before or after C74.
Here are the other signals that are shown on the schematics.
Here is how the output looks with the 10" subwoofer.
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