Soundstream Rubicon 1.2500 in protect

[bigpun4fubu]

The rca jacks contacts broke loose from the board due to vibration and tension on cables, so my friend switched the rca's to other set of jacks (labeled Line out) and it worked fine, then the same problem occurred again and the subs would have a lot of feedback and rumble , so he replaced the rca jacks and they have a solid connection the amp rumbled the subs again and then went into protect, could this be one of the op-amps failed at the RCA's by chance ?

 

[bigpun4fubu]

 

[timwebb]

were they pulsing in and out? sounds like a shorted output transistor.

 

[bigpun4fubu]

from what he described yes

 

[timwebb]

check the output transistors and the driver transistors for them.

 

[bigpun4fubu]

which ones are the drivers on the driver board?

 

[timwebb]

all of them are drivers. i think they are split in two groups for each half of the output fets. u can confirm by doing a ohm check from the output gate resistor to the ones on the driver card.

 

[bigpun4fubu]

 

[Perry Babin]

What was the signal source?

Were the speakers producing a low frequency rumble or was it a pulse that drove the speaker in/out approximately 1/second?

 

[timwebb]

the larger ones are the drivers

 

[bigpun4fubu]

low freq rumble so far all transistors check good

 

[bigpun4fubu]

What was the signal source?

Were the speakers producing a low frequency rumble or was it a pulse that drove the speaker in/out approximately 1/second?

im asking him to be definitely sure of this

 

[Perry Babin]

If the amp only has this fault with the RCAs plugged in and he's using a standard head unit, tell him to check the RCA shield ground.
RCA Shield Repair

 

[bigpun4fubu]

it goes into protect with no rcas connected

 

[Perry Babin]

I never worked on this model but most of these amps illuminate the protect LED for 3-9 seconds. At the end of the delay, the LED goes from red to green.

Does it rumble with no RCAs connected?

Is there any DC present on the output terminals from the time the amp powers up to the time the LED goes green?

 

[bigpun4fubu]

led stays red stays in protect

 

[Perry Babin]

Does it rumble with no RCAs connected?

Is there any DC present on the output terminals from the time the amp powers up?

 

[bigpun4fubu]

it spike up to -3.5v dc when it tries to power up then drops when it kicks into protect

 

[Perry Babin]

Counting from the op-amp end of the driver board, pin 6 should have nearly rail voltage during the mute delay and then drop to near ground when the mute delay ends.

Is this what you see?

How long does it take from the time that remote voltage is applied until the voltage on that pin drops to near ground?

 

[bigpun4fubu]

he says it was pulsing btw , ill check the rail voltage and post those results