Soundtream RUB1.2500D

[S Merlington]

Anyone know what transistors usually fail on this driverboard??

They all test good but as soon as i install it in the amp the amp will start drawing excessive current..

Outputs are brand new so i know thats not an issue also everything on the main board tests fine..

 

[Perry Babin]

Q43 is suspect.

 

[S Merlington]

Q43 is a A1776 ..

Is there a good sub for that transistor for testing before i place a parts order ?

 

[Perry Babin]

The KSA1220A may survive. It works in other amps but they may have lower rail voltage (±78v greatest rail voltage in amp that I used the 1220A in).

 

[S Merlington]

Is the Pin out the same for the A1776 and the A1220 ?

I cant seem to find a datasheet that shows pin out for the 1776

 

[Perry Babin]

Pull another one and check it.

 

[S Merlington]

The 1776'S test fine but they are a brownish color from excessive heat ..

I will swap them out for the A1220's for testing ..

Do the 1220'S face the same direction or do i install them backwards?

 

[S Merlington]

Replaced all the 1776's with the A1220's

There's still a problem with the driverboard it makes the amp draw excessive current ..

I know it's on the driverboard because I stuck a diffent one in the amp and it plays just fine and idles perfectly.

 

[Perry Babin]

What is the DC voltage across ZD6 and R95?

 

[hadidin]

hi i have problem with this amp too my amp output have signal but it is not clear current drawing is ok everything good but i have some over hiting on driver board i think problem is there any idea?
thanks

 

[Perry Babin]

Please don't post in a repair thread that was started by someone else unless you are trying to offer assistance to the original poster.

Click on the red triangle in the lower left corner of your post and ask a moderator to move your post (and any replies to it) to a new thread (my post should be deleted).

 

[S Merlington]

Replaced all the drivers on the audio driver board..

Amp is up and running flawless..

 

[Tieftoener]

Replaced all the drivers on the audio driver board..

Amp is up and running flawless..

Thanks for posting your fix.

 

[S Merlington]

got this amp back with a blown power supply..

replaced the power supply fets now i have a strange issue with it..

Theres is 1.22 volts meaured directly across the speaker terminals..

If i wiggle the RCA jacks around the voltage on the speaker terminals pulse's i can get all the way up to 16 volts the it drops back down to 1.22 volts by wiggeling the rca jacks.. Any ideas?

 

[Perry Babin]

With no RCAs plugged in, what the resistance from the input RCA shields to the negative speaker terminal?

Move the RCAs while checking to see if you get a steady reading.

 

[S Merlington]

1.008 M ohms..

The voltage across the speaker terminals is steadt now and its at -2.57 vokts its negative voltage

 

[Perry Babin]

Check R100.

 

[S Merlington]

Do you have a pic or can tell me where R100 is ?

If R100 is a 220 ohm it measures 218.6 ohms

 

[Perry Babin]

If I'm not mistaken, one end connects to the input RCA shields and the other end connects to the secondary ground (negative speaker terminal).

 

[S Merlington]

Yeah you car correct..

Between RCA input shields and negative speaker terminal i get 218 ohms so R100 is within tolorance..

I found a broken ground on the rca jacks fixd it..

Now i still get -2.57 volts on the speaker terminals..

Any ideas where to begin to start looking ?