Rockford Fosgate T1500-1BDCP

[Perry Babin]

With the black probe on ground:
http://www.bcae1.com/temp/rockfordt1500-1bd02.swf

 

[caraudioguy2100]

Ok those appear correct voltages after placing black probe on ground Germaine .

How do I measure the rail voltage in this amp ?

 

[Perry Babin]

Across the center legs of the two rectifiers. Don't slip. Alternatively, you should be able to touch to the tabs of the transistors.

 

[caraudioguy2100]

I get 99 volts of rail voltage is this correct or is it low ?

 

[Perry Babin]

I don't know what it is supposed to be but if it's producing rail voltage, that's probably right. I see 100v rail caps in the photos I have.

 

[caraudioguy2100]

Back to this amp .

The amp has very distorted output sounds like I’m plugging the test speaker into a wall outlet .

The voltage at the speakers terminals is 0.00 so that’s not and issue .

Any ideas ?

 

[Perry Babin]

Post a photo of the waveform. Drive a 50-100Hz signal into the amp. Set the scope to 2ms and 5v/div. Drive the amp hard enough to make the waveform cover most of the display.

 

[caraudioguy2100]

I will have to get back to you on that either the probe or the scope is no good it won’t lock on a waveform .

Unless is picking up noise or something it’s on the bottom level of my house next to my power supply

 

[Perry Babin]

If by power supply, you means the mains panel, that won't cause a problem.

Try setting the trigger to manual and adjusting the trigger level.

Can you view a power supply waveform (10us and 5 or 10v/div, depending on the point probed)?

 

[caraudioguy2100]

Yes I can view the power supply waveform perfectly .

Wondering can mismatched outputs cause this problem in this amp ?

 

[Perry Babin]

Mismatched? Do you mean different date codes or do you mean different part numbers?

 

[caraudioguy2100]

Different date codes

 

[Perry Babin]

That won't cause it to be distorted.

Try paralleling a capacitor across the speaker terminals with your dummy load/speaker. Does that allow your scope to lock on?

Use a mylar/film cap of about 10uf if you have one. If you have to use polarized caps, connect two in series with reverse polarity (negatives together).

 

[caraudioguy2100]

I let this amp sit for a couple of weeks and now when I power it up it works perfectly fine .

Any ideas why it had distorted output then letting the amp sit now it works perfectly fine?

 

[Perry Babin]

Push/pull/tap/heat/cool everything to see if you can cause the problem to return. It's very rare for an amp to fix itself... reliably.

 

[caraudioguy2100]

The amp will distort when first powered on but if it plays for a min the distortion goes away and the amp plays fine .

Not sure if it’s in my head unit or test sub I will try to get a pic of the waveform