Rockford Fosgate T1500-1BD

[S Merlington]

There is no rail voltage in the amp.. Power supply seems to be working Since i have 5 volts on the gate leg and 13 volts on the middle leg and 0 volts on the third leg..

I checked the rail voltage at the Rectifiers (mur1620 and mur1620R) And the voltage pulse's up and down its no steady i puled the rectifiers from the board they test fine..

Should i replace them and see what happens or does anyone have any thoughts on what to check??

 

[S Merlington]

Ok replaced both rectifiers in the amp still no change amp does not produce rail voltage..

Anyone have any ideas on what to check ?

 

[blazer40]

Do you have a scope?

 

[seankane]

Post the voltages on the main IC on the PWM board. I am sure it's a 494 or 594.

 

[S Merlington]

Its a 3526

Pin 1:4.95
Pin 2:3.62
Pin 3:4.17
Pin 4:4.70
Pin 5:4.96
Pin 6:0.00
Pin 7:0.00
Pin 8:4.95
Pin 9:3.60
Pin 10:2.04
Pin 11:0.00
Pin 12:5.40
Pin 13:5.56
Pin 14:13.32
Pin 15:0.03
Pin 16:5.82
Pin 17:13.81
Pin 18:5.35


Yes i have a scope..

 

[blazer40]

Does the signal on the gates of the 75344's look nice and clean? (swinging ~5v)..

 

[S Merlington]

Yes

 

[blazer40]

But no DC across the two middle legs of the rectifiers?

 

[S Merlington]

On the MUR1620 i get

Leg 1:-0.27
Leg 2:1.50
Leg 3:0.00


On The MUR1620R

Leg 1:-0.94
Leg 2:-2.14
Leg 3:-0.84

 

[blazer40]

If your meter is in DC mode, probes on the middle pin of each rectifier(red on middle pin of the 1620 and black on the middle pin of the 1620r), what reading do you get?

 

[S Merlington]

76.9 volts

 

[blazer40]

good... That's rail voltage. Is this just a no audio problem from this amp?

 

[S Merlington]

Yeah i get no audio from the amp

 

[blazer40]

Any dc on the outputs?

 

[S Merlington]

No

 

[blazer40]

black probe on the negative power terminal of the amp for the next 3 tests...

what is the voltage on the 3rd(righthand) pin of the 3 44h11's and the single 45h11 smd transistors right in the middle of the main board?

 

[S Merlington]

Q2012:11.66
Q2010:11.66
Q2017:6.36

45H11:1.00

 

[blazer40]

that 45H11 should have -6 volts.

Black probe still on the negative terminal of the amp, what are the voltages on the 1st and 2nd leg of the 45h11?

 

[S Merlington]

Leg 1:-6.82
Leg 2:-27.05
Leg 3:1.00

 

[blazer40]

Yep, that 45H11 is bad.