Rockford Fosgate 1001bd is dead, please help!

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Jump to Latest
B

bzb07

Member
Joined 2014
I got this amp dead a long time ago. I just stashed it away until I could learn how to repair it. I have always had a fascination with electronics, and have done minor repairs to things over the years. I feel I still don't have the skill set to take on this project alone, and could use as much help as possible. Please be patient with me-especially if the info you provide needs to be "spoon-fed". I have a read a couple of threads on here recently, and this site is very informative/helpful. I think the problem with the amp may be the PWM IC, but I don't know enough to confirm this. Power FETs seem to check out fine. I don't have 70v on the twisted pair, and the U21 has voltage on pins 5 &6. Here is the status of the 3526 & LM339
Pin
1 5v
2 0
3 0
4 0
5 1.7v
6 0
7 0
8 0
9 3.6v
10 2v
11 0
12 5v
13 0
14 12.7v
15 0
16 0
17 12.7v
18 5v

LM339
Pin
1 1.7v
2 1.7v
3 12.7v
4 0
5 1.9v
6 3.9v
7 5v
8 rises?
9 rises?
10 5v
11 7.5v
12 0
13 1.7v
14 0

Thanks in advance for you help!
 
B

bzb07

Member
Joined 2014
Perry Babin said:
There is a problem with the voltages. There are points that are directly connected but have different voltage on them. Re-check the voltage on all pins.
Click to expand...


OK, checked again with a more trusted meter & got a refresher on IC pin layouts ;), and here are the updated values:

3526
Pin
1 5v
2 .4v
3 1.2
4 .5v
5 2.7v
6 0
7 0
8 2.7v
9 3.6v
10 5v
11 12.7v
12 0
13 0
14 10v
15 0
16 5v
17 0
18 0

LM3390
Pin
1 2.7v
2 2.7v
3 12.7v
4 0
5 1.9v
6 3.9v
7 5v
8 0
9 1.7v
10 5v
11 7.5v
12 0
13 2.7v
14 0
 
B

bzb07

Member
Joined 2014
Perry Babin said:
That corrected some problems but not all.

With 12.7v on pin 3 of the LM339, you should have the same on pin 17 of the 3526. Measure the resistance between those pins. You should read near 0 ohms.

Also check R21.
Click to expand...

I am so sorry, I read the back row in reverse. I do have continuity from pin 3(LM339) to pin 17(3526).

3526
Pin
1 5v
2 .4v
3 1.2
4 .5v
5 2.7v
6 0
7 0
8 2.7v
9 3.6v
10 0
11 0
12 0
13 0
14 12.7v
15 0
16 0
17 12.7v
18 5v

R21= 72.5 Ohms
 
J

jwilhelm

Member
Joined 2014
vzaudio.com/
I'm not familiar with this amp but first thing to look at in a car amp is output devices. If they short either the transformer section will be shut down by protection circuits or if you're not so lucky the fets will melt. Most problems start from high current sections of the amp. It's rare to see an IC fail unless something else failed and took it with it.
 
P

Perry Babin

Member
Joined 2003
bcae1.com
Pins 1, 2 and 13 of the 339 should be near 5v. There's nothing on the various input pins that would be preventing the voltage from rising. Pin 8 of the 3526 is connected to those pins and should be near 5v as well. A problem with either of the ICs could be preventing the voltage from reaching 5v. There does appear to be a problem with the 3526 since pin 10 is at 0v. It should be near 2v. That could indicate that the 3526 is defective, especially if you don't read 0 ohms between pin 10 and ground.

Has anyone replaced any parts in the amp?

R21 should be marked 1R0 and read very near 1 ohm.
 
B

bzb07

Member
Joined 2014
Perry Babin said:
Pins 1, 2 and 13 of the 339 should be near 5v. There's nothing on the various input pins that would be preventing the voltage from rising. Pin 8 of the 3526 is connected to those pins and should be near 5v as well. A problem with either of the ICs could be preventing the voltage from reaching 5v. There does appear to be a problem with the 3526 since pin 10 is at 0v. It should be near 2v. That could indicate that the 3526 is defective, especially if you don't read 0 ohms between pin 10 and ground.

Has anyone replaced any parts in the amp?

R21 should be marked 1R0 and read very near 1 ohm.
Click to expand...

No parts have been changed that I am aware of.
R21 is labeled 1R0. Do I need to pull the resistor from the board to measure the resistance?

I will check pin 10 in the morning. Thanks again Perry for being so patient with me!
 
P

Perry Babin

Member
Joined 2003
bcae1.com
Sometimes residual DC voltage can skew readings. If it reads the same value both ways (leads reversed) in the board, it's almost certainly defective. If not, remove it and check it. With a 1 ohm resistor, residual voltage isn't likely to be a problem.

Touch your probes together to confirm that it reads 0 ohms before checking the resistor.
 
B

bzb07

Member
Joined 2014
Perry Babin said:
Sometimes residual DC voltage can skew readings. If it reads the same value both ways (leads reversed) in the board, it's almost certainly defective. If not, remove it and check it. With a 1 ohm resistor, residual voltage isn't likely to be a problem.

Touch your probes together to confirm that it reads 0 ohms before checking the resistor.
Click to expand...

I have removed R21 (1R0) and confirmed a reading of 27 ohms with the leads reversed. I have replaced the resistor with a 1 ohm. Is it safe to power the amp, or should I replace the PWM IC before doing so? Thanks.
 
B

bzb07

Member
Joined 2014
Perry Babin said:
No. We're working on the power supply at this point. U10 is in the audio circuit. The 3526 is the power supply driver IC.

If you don't have a scope, post the voltages on the 3526.

Has anyone replaced the 3526 previously?
Click to expand...

Voltages with the remote and ground only. B+ disconnected.
3526

1: 5
2: 0
3: 0
4: 0
5: .4
6: 0
7: 0
8: .4
9: 3.6
10: 2.1
11: 0
12: 5
13: 0
14: 12.3
15: 0
16: 0
17: 12.3
18: 5
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Top Bottom