Rockford Fosgate P10002

[rafi77]

Hello everyone I'm new to this electronic repair, so I'm kinda lost on were I should begin testing the amp in order to fix it. The reasons I wanna repair the amp myself is 1) save money, and 2) I wanna learn how. Now the problem with my amp is one channel plays but the other does not play any audio, but it does send out a signal that causes my subs to smoke. When it stopped working I had the amp bridged playing clean and awesome. And when the channel blow it also fried the voice coils on my subs. For the life of me I can't figure why it blew, or what's wrong with it. I don't see any physical damage, soot (sp?), or melt downs. Any help will be greatly appresiated. Thank you

 

[Perry Babin]

If you're new to amp repair, please read the basic amp repair page (link below).

Do you have a multimeter?

 

[rafi77]

i have a multimeter (fluke), and i read the site and checked the transistors like it said, and they all failed two of the three test. because of this im kind of doubtful i did it right because one channel still plays and the amp doesn't go into protect mode or anything, but the test tells me their all defective. thank you for your help perry

 

[Perry Babin]

Of the transistors marked 28N15 and 36P15, which ones read near 0 ohms when you place the probes on legs 2 and 3?

 

[rafi77]

Q1028 - 36P15 - 2.26 (slowly decreases)
Q1022 - 36P15 - 2.421 (slowly decreases)
Q1025 - 36P15 - 1.575 (slowly decreases)
Q2028 - 28N15 - 00.2
Q2024 - 36P15 - 1.63 (slowly decreases)
Q2029 - 36P15 - 1.822 (slowly decreases)
Q2020 - 36P15 - 2.045 (slowly decreases)

There is only one 28N15 and the rest are 46N15. I tested them with the fluke set to ohm like the basic transistor testing says to.

 

[mike49504]

Q2028 is defective

 

[rafi77]

Should i also replace the resistor for that transistor?

Thank you

 

[Perry Babin]

Yes. Q2028 is shorted but you should have three N-channel FETs and three P-channel FETs in each channel. What are the following transistors?

Q1026
Q1029
Q1031
Q2021
Q2025

Is the amp below the same as yours?

 

[rafi77]

Q1026 - 46N15
q1029 - 46N15
q1031 - 46N15
q2021 - 46N15
q2025 - 46N15

Yes my amp looks just like it, but at the bottom of the board underneath were it says Rockford Fosgate it says P1200.2 instead of P1000.2. Pics below

 

[mike49504]

Perry,

Does that look strange? Q2028 a 28n15? and the rest 46n15's and 36n15's?

I dont think there should be a 28n15 in this amp.

Rafi has this amp been worked on before do you know??

 

[rafi77]

Yeah, thats why I wanna fix it myself because I don't think buddy did a good job. I was thinking the same thing and I also found it strange that there is only one 28N15 when the rest are 46N15 and 36P15.

 

[mike49504]

I dont think there should be a 28n15 anywhere on the board.

On the board in question with the 28n15 on it. how many 36n15's or 46n15's are on that board along with the 28n15

 

[rafi77]

5 - 46n15

1 - 28n15

6 - 36p15

 

[mike49504]

the 28n15 should be a 46n15

 

[rafi77]

the 28n15 should be a 46n15

Thank you so much for your help

Do you think I should change all of the fets (l/r channel) just to have them all fresh from the same batch and should I change the resistors too? Thanks

 

[mike49504]

I would switch all the outputs with new so they share the load the same.

Also test the resistors and post the results

 

[rafi77]

thats what I was thinking, but I just wanted to be sure on switching them out. i'll test the resistors now.

 

[Perry Babin]

Do any of the 46N15s read shorted?

 

[rafi77]

I'm in class right as soon as I get home I will post the results.

 

[rafi77]

Q1026 - 46N15 - 5.77k (and rising)

Q1029 - 46N15 - 5.77k ohm (same)

Q1031 - 46N15 - 5.63k ohm (same)

Q2021 - 46N15 - 45.3

Q2025 - 46N15 - 45.3

resistors
R1093 - 0.3
R1100 - 0.3
R1107 - 0.4
R1099 - 0.3
R1081 - 0.3
R1092 - 0.3

R2081 - 0.3
R2092 - 0.3
R2099 - 45.4
R2091 - 0.3
R2105 - 0.2
R2079 - 0.3