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RockfordFIx 4th December 2012 04:07 PM

Rockford Fosgate T40001BD Repair
I am repairing a T40001BD and having a little trouble find a schematic. Can someone please email me a copy of a T40001BD schematic to

I have replaced the output FETS and the powersupply FETS checked out fine. When powered up my +HV is around ~9v and my -HV is ~110v.

Perry Babin 4th December 2012 04:55 PM

Check your email. You can get most Rockford schematic diagrams from Rockford.

RockfordFIx 4th December 2012 05:25 PM


Thanks for your help....might have a few questions for you after get home and check some test points to find out where i am losing my high voltage at.


Perry Babin 4th December 2012 05:59 PM

BD amps don't have static rails. In this amp, there is one 120v rail. The rail is shifted up above ground by 120v or driven below ground by 120v as needed by the output stage.

If you have a scope, that will be helpful when troubleshooting.

RockfordFIx 4th December 2012 07:47 PM


I have been meaning to buy a scope. Should i also invest in a signal generator too?

seankane 4th December 2012 08:35 PM

You could buy one but I would save your money. You can download test tones and burn them to cd's and just use a head unit.

You can also load test tones on your i-pod or phone and use the 1/8" jack to male rca and plug it directly into the amp.

These options would work great for amp repairs.

Perry Babin 4th December 2012 09:01 PM

I agree that you don't really need a signal generator.

I'd suggest a proper head unit with the proper protection. You can use an ipod but some amps will not work properly with any audio source with a floating ground (like an ipod). You can ground the shield to make it usable but you have to protect the shield ground like a standard head unit.

If you use an ungrounded signal source, you'll also miss problems like intermittently shorted transformers. If you are repairing an amp for someone and you miss an intermittently shorted transformer, you may be asked to pay for the damage to the vehicle or to the head unit when they connect it and cause damage to their vehicle or equipment.

RockfordFIx 6th December 2012 06:23 PM


should i be getting ~120 for both -HV and +HV at the same time. With the ground wire only connected to the output board i read ~110 on +HV and ~-5 on -HV. When connected i read ~5 on +HV and ~-110 on -HV.

Perry Babin 6th December 2012 08:23 PM

You don't measure rail voltage referenced to ground on these amps. You measure across the red and blue wires.

RockfordFIx 6th December 2012 09:51 PM

thanks for clearing that up. bringing home a fluke 97 scope meter this weeking and will hookup a descent headunit. I have a pyramid 52amp powersupply i purchased off of ebay but the output is at max for 14.5v. used my droid for pandora for an input to the amp hooked up to the powersupply. seemed to clip/distort a little with gain up and thats what made me look at the rail voltage. But now i am wondering if the powersupply is not producing enough power. Will get a car battery and check and see.

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