Rockford Fosgate T5002

[Perry Babin]

What is the DC voltage on the following resistor when the bias pot is at each extreme position?

R1037
R1040
R1029
R1030
R1032

 

[S Merlington]

R1037:45.1
R1040:-45.5
R1029: 1 side 4.05 other side 13.44
R1030:2.95
R1032: 2.30

 

[Perry Babin]

I should have used 'across' instead of 'on' when I asked for the voltage on each resistor. Measure the DC voltage directly across each of those resistors.

 

[S Merlington]

R1037:0
R1040:0
R1029:9.48
R1030:0.74
R1032:0.12

 

[S Merlington]

Do the voltages look normal or are they way off in the post above?

 

[S Merlington]

R1037:0
R1040:0
R1029:9.48
R1030:0.74
R1032:0.12

 

[Perry Babin]

Lift Q1009 and Q1010 and post them again.

Post the voltage at both extremes of the bias pot.

 

[S Merlington]

R1037:0
R1040:0
R1029:0
R1030:0
R1032 :0


Right Channel Bias pot:0

Left Channel:1.05

 

[S Merlington]

R1037:0
R1040:0
R1029:0
R1030:0
R1032 :0


Right Channel Bias pot:0

Left Channel Bias Pot:1.05

On the Bias transistors here are the voltages i get

Left Channel

Base:-0.44
Collector:0.50
Emitter:-0.39

Right channel

Base:2.39
Collector:1.53
Emitter:13.12

 

[Perry Babin]

Lets work with the 1000 series channel for now. I need the voltage across those resistors with the bis pot fully clockwise and with the bias pot fully counter-clockwise.

Are you sure that you have the voltage/pin configuration correct for the bias transistors? The voltage shouldn't be higher on the emitter than on the collector.

 

[S Merlington]

Fully clockwise

R1037:0
R1040:0
R1029:0
R1030:0
R1032:0

Fully counter clockwise


R1037:0
R1040:0
R1029:0
R1030:0
R1032 :0

Theese voltages are with Q1009 and Q1010 lifted

Heres the datasheet i went by for the bias transistors
MUN2111T1 pdf, MUN2111T1 description, MUN2111T1 datasheets, MUN2111T1 view ::: ALLDATASHEET :::

If thats correct pin config heres what i get on the bias transistor

Base:0.40
Emitter:-0.43
Collector:0.47

 

[Perry Babin]

Does 0v mean 0.000v?

What is the DC voltage across pins 1 and 2 (from the pin configuration on the datasheet you posted) for D1006 and D1007?

 

[S Merlington]

Yes it means 0.000

D1006:0.44

D1007:0.06

 

[Perry Babin]

Lift Q2009 and Q2010 in the other channel and confirm that you read 0.000v across all corresponding resistors in that channel and confirm that you have essentially 0v across the speaker terminals for the 2000 series channel.

 

[S Merlington]

Lifted Q2009 and Q2010 and get 0.000 volts acros all the 2000 series resistors as well..

I get 0.02 volts across the speaker terminals

 

[Perry Babin]

At one time, the amp was burning the 604 ohm resistors. What did you do to stop that?

 

[S Merlington]

I replaced the LM317 and The LM337 and it stopped burning the resistors..

The crazy thing about this amp is If i lay my finger across the board around the Q1000 all th way to Q1005 I can get the distortion to go away and output is clean


If i do the same for the 2000 series parts that channel also has clean output as soon as i remove my finger from the board the distortion comes back..

I removed all the components in that area (1000 series parts) cleaned the board and resolderd everything still distorts until i lay my finger across the board..

If i try to bridge the amp Left + right - i get very lil output almost no output at all

 

[Perry Babin]

I'm assuming that you tried this previously (not recently where Q1009, Q1010, D1002-2005 are supposed to be out of the board).

 

[S Merlington]

correct

 

[Perry Babin]

I'm stumped for now. You've verified that all of the various supplies are present and it appears that you've checked all components in the channel. Generally, when both channels are affected, the problem is a power supply or control issue.

email me.
babin_perry@yahoo.com