I actually found a local shop in my neighborhood that stocks a lot more parts than I'd expected. He has about 90% of that I need for most repairs, and the prices and price breaks makes purchasing from him very conveient and competative compared to online. I told him he's like an old-school radioshack and he just laughed. He sells NTE parts, but also TI, IRF, ST, and onSemi and he specializes in parts ready for amplifier and stereo repair. Its http://www.audiolabga.com/. Its nice to have a place like this close-by.
He sold me all IRF power fets and 540/9540 transistors for less that $2 a piece, but he looked at me very funny when I said I was going to use IRF3205Z in place of 50n06v for supply fets. He said the power output is much higher on the IRF3205Z transistors.
Does this pose any problems with this and other rockford amps? Does going from 50n06v to IRF3205Z in essence upgrade an amplifier's output ability? What about the gate resistors. 50n06v uses 10 ohm. Are the IRF3205Z good with this or something else? I need to buy resistors anyways.
One thing the guy did not have were the 1G/2G SMD transistors so I'll have to get those online. He did have TI TL494 surface and through-hole so I grabbed up one of each.
He sold me all IRF power fets and 540/9540 transistors for less that $2 a piece, but he looked at me very funny when I said I was going to use IRF3205Z in place of 50n06v for supply fets. He said the power output is much higher on the IRF3205Z transistors.
Does this pose any problems with this and other rockford amps? Does going from 50n06v to IRF3205Z in essence upgrade an amplifier's output ability? What about the gate resistors. 50n06v uses 10 ohm. Are the IRF3205Z good with this or something else? I need to buy resistors anyways.
One thing the guy did not have were the 1G/2G SMD transistors so I'll have to get those online. He did have TI TL494 surface and through-hole so I grabbed up one of each.
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I actually found a local shop in my neighborhood that stocks a lot more parts than I'd expected. He has about 90% of that I need for most repairs, and the prices and price breaks makes purchasing from him very conveient and competative compared to online. I told him he's like an old-school radioshack and he just laughed. He sells NTE parts, but also TI, IRF, ST, and onSemi and he specializes in parts ready for amplifier and stereo repair. Its Audio Lab of Ga. Its nice to have a place like this close-by.
**** email me: babin_perry@yahoo.com
He sold me all IRF power fets and 540/9540 transistors for less that $2 a piece, but he looked at me very funny when I said I was going to use IRF3205Z in place of 50n06v for supply fets. He said the power output is much higher on the IRF3205Z transistors.
**** This makes no sense.
Does this pose any problems with this and other rockford amps? Does going from 50n06v to IRF3205Z in essence upgrade an amplifier's output ability?
**** No. Unless you were going to run the amp into a lower impedance load than recommended, the 3205s will make no difference. At lower impedances, the only difference would be that the 3205s would survive longer.
What about the gate resistors. 50n06v uses 10 ohm. Are the IRF3205Z good with this or something else? I need to buy resistors anyways.
**** The 10 ohm resistors are OK.
**** email me: babin_perry@yahoo.com
He sold me all IRF power fets and 540/9540 transistors for less that $2 a piece, but he looked at me very funny when I said I was going to use IRF3205Z in place of 50n06v for supply fets. He said the power output is much higher on the IRF3205Z transistors.
**** This makes no sense.
Does this pose any problems with this and other rockford amps? Does going from 50n06v to IRF3205Z in essence upgrade an amplifier's output ability?
**** No. Unless you were going to run the amp into a lower impedance load than recommended, the 3205s will make no difference. At lower impedances, the only difference would be that the 3205s would survive longer.
What about the gate resistors. 50n06v uses 10 ohm. Are the IRF3205Z good with this or something else? I need to buy resistors anyways.
**** The 10 ohm resistors are OK.
I replaced the power fets, 1G, 2G, gate resistors, two outputs, and two source resistors. Amp powers up and is stable on bench. Channel which I replaced the outputs seems good at this point where there is minimal DC volts on speaker terminals. The channel right next to the one I repaired is also measuring up fine.
On the other side of the amp; where I have not done any repairs at al; I'm getting ~4vDC on the bridging speaker terminals referencing amp general ground. I started poking around and cant find any broken trace or signs of problem components. I tested D16 diode and it is good.
On the other side of the amp; where I have not done any repairs at al; I'm getting ~4vDC on the bridging speaker terminals referencing amp general ground. I started poking around and cant find any broken trace or signs of problem components. I tested D16 diode and it is good.
Resistance from all 4 channel RCA inputs to amp ground is .8k. While powered if I ground either bad RCA shield the output voltage drops down to just a few milivolts.
I found C112 i nthe center of the board as pictured above - Its the 10uF/16v cap in-line with 12 surface mount transistors; C112 is the cap on the left looks to have been isntalled at a 45 degree rotational angle and is not making contact with the pads. I'm going to unsolder it and check it out.
I found C112 i nthe center of the board as pictured above - Its the 10uF/16v cap in-line with 12 surface mount transistors; C112 is the cap on the left looks to have been isntalled at a 45 degree rotational angle and is not making contact with the pads. I'm going to unsolder it and check it out.
PROGRESS! Fixing C112 didnt change anything. I went and took out the only diode on the entire PCB: D16 - and now the two bad channels are working just fine - no vDC and good audio playback. This seems like somewhat of a similar problem I was having with another RF DSM amp so I'll keep poking about.
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