Rockford fosgate t10001bd sqealing for 10s

fongman · 7th February 2010, 09:14 AM

I bought this amp from ebay awhile ago, and never fully tested it. But when i appled power it have this sqealing sound? Goes away about 10s, amp powers on and plays but I noticed the fan is not working. I test the two pin on the fan input and reads about .5volts. Not enough to power the fan. No protection light also. I'm not sure if Q31 and Q34 of the fan circuit is bad? Any help would be great.

Perry Babin · 7th February 2010, 11:31 AM

The fan is 2 speed and doesn't run when the amp is cool.

Does it produce the noise with no RCAs plugged in?

fongman · 7th February 2010, 04:59 PM

Yes, with or without. But only for 10 second. Afther that if I turn the power off and on no noise. If I wait about 10 to 15 minutes, it will have the noise again. Thank you for the help Perry.

Perry Babin · 7th February 2010, 05:31 PM

After it powers up, does it produce strong, clean output?

fongman · 7th February 2010, 06:18 PM

Yes, on the bench test. Last week when I install the amp in the truck it had no sound. I will try the amp in the truck today and post up what happened.

fongman · 8th February 2010, 12:10 AM

I install the amp and the sound is loud and clear. But the noise was there the 1st 5 to 10 sec. Sound like it was coming from the power supply? The outputs check out okay.

Perry Babin · 8th February 2010, 03:45 AM

Put it back on the bench and see if you see any noise on any of the op-amps on pins 4 and 8 (for the 8 pin op-amps) when it powers up.

Also look for noise on pins 1 and 7 of the op-amps.

The voltage on all of these pins should be a straight line. Set the scope's vertical amplifier to 5v/div and set the timebase to 2mS. Set the coupling to DC.

fongman · 8th February 2010, 06:26 AM

Perry i don't have a scope, can i test it anyother way?

Perry Babin · 8th February 2010, 01:14 PM

Do you have an old home stereo receiver? If so, you can use the method used in the following post:
Help please

fongman · 8th February 2010, 04:07 PM

I don't but can buy one.

7th February 2010, 09:14 AM	#1
fongman diyAudio Member Join Date: Jan 2009	Rockford fosgate t10001bd sqealing for 10s I bought this amp from ebay awhile ago, and never fully tested it. But when i appled power it have this sqealing sound? Goes away about 10s, amp powers on and plays but I noticed the fan is not working. I test the two pin on the fan input and reads about .5volts. Not enough to power the fan. No protection light also. I'm not sure if Q31 and Q34 of the fan circuit is bad? Any help would be great.

7th February 2010, 11:31 AM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	The fan is 2 speed and doesn't run when the amp is cool. Does it produce the noise with no RCAs plugged in? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

7th February 2010, 05:31 PM	#4
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	After it powers up, does it produce strong, clean output? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

8th February 2010, 03:45 AM	#7
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Put it back on the bench and see if you see any noise on any of the op-amps on pins 4 and 8 (for the 8 pin op-amps) when it powers up. Also look for noise on pins 1 and 7 of the op-amps. The voltage on all of these pins should be a straight line. Set the scope's vertical amplifier to 5v/div and set the timebase to 2mS. Set the coupling to DC. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

8th February 2010, 01:14 PM	#9
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Do you have an old home stereo receiver? If so, you can use the method used in the following post: Help please __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links


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7th February 2010, 04:59 PM	#3
fongman diyAudio Member Join Date: Jan 2009	Yes, with or without. But only for 10 second. Afther that if I turn the power off and on no noise. If I wait about 10 to 15 minutes, it will have the noise again. Thank you for the help Perry.

7th February 2010, 06:18 PM	#5
fongman diyAudio Member Join Date: Jan 2009	Yes, on the bench test. Last week when I install the amp in the truck it had no sound. I will try the amp in the truck today and post up what happened.

8th February 2010, 12:10 AM	#6
fongman diyAudio Member Join Date: Jan 2009	I install the amp and the sound is loud and clear. But the noise was there the 1st 5 to 10 sec. Sound like it was coming from the power supply? The outputs check out okay.

8th February 2010, 06:26 AM	#8
fongman diyAudio Member Join Date: Jan 2009	Perry i don't have a scope, can i test it anyother way?

8th February 2010, 04:07 PM	#10
fongman diyAudio Member Join Date: Jan 2009	I don't but can buy one.

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