Help repairing Soundstream 405s

[kmarei]

i have 2 Soundstream 405s amps
one for left and one for right side
the one i just got for the right side has one channel that has 20v across the speaker terminals (its one of the 4x50w channels, not the mono sun channel)
i opened it up and i found one resistor (R426) that looks burnt
and it's the only one that doesn't beep when i test it with a multimeter
to get this working, i was going to start with changing this resistor and seeing where it leads me

all the other similarly sized ones (R226, R227, R326, R327, R427, R526, R527) beep when i test them
any advice on where to source the resistor
the one next to it looks a little burnt too, was going to change that as well

or does anyone have a service manual or schematic diagram?
thanks a lot
i also have another 1000s that refuses to work bridged, works fine in stereo
and a 644s that works fine high pass or all pass, but not low pass
will start on those when i fix this one

thanks a lot

[jol50]

That kind of power on the speakers is usually shorted outputs or maybe a driver issue. Check the outputs, in many SS they are under the board (w/a bolt between them) but you should see the three pins for each. One of the legs will go to the bridging terminal of your bad channel for the two or four outputs on that channel. If any of the three are shorted to another (near 0 ohms) they are bad. Try mouser.com for parts.

[Perry Babin]

If that resistor opened, the outputs in that channel are likely shorted. If only one is shorted, replace both of them as well as both 0.27 ohm resistors.

Mouser:
660-MOX2LT631RR27J
511-TIP102
511-TIP107

Email me if you want the schematic diagram.
babin_perry@yahoo.com

[kmarei]

Originally Posted by Perry Babin

If that resistor opened, the outputs in that channel are likely shorted. If only one is shorted, replace both of them as well as both 0.27 ohm resistors.

Mouser:
660-MOX2LT631RR27J
511-TIP102
511-TIP107

Email me if you want the schematic diagram.
babin_perry@yahoo.com

i had emailed you when i read on another thread you had the manual for a 405
my email is my username at hotmail

sorry i didn't get what you said
what value is the bad resistor (R426)?
and which other ones should i change?
the one next to it i wanted to change anyway (R427)
but are you saying i should change more?
can you give me values/Resistor numbers?
thanks a lot

[kmarei]

on another note
once i have the amp working (i hope )
how would i set the gains on the 2 sides?
one amp will be left side of car (front, rear, sub)
and one for right.
how do i make sure they are level matched?

i was thinking a 1khz sine wave and measure the voltage at the speaker terminals and adjust the gain till both amps put out the same voltage
is that right or wrong?

[kmarei]

you are both right
both drivers have a short on 2 pins
will order 2 resistors and 2 drivers from the link provided
thanks a lot guys

[Perry Babin]

For future reference, those are better referred to as output transistors than drivers. Drivers are typically one stage behind the outputs.

When you measure the output voltage for each bridged pair of channels, make sure that each individual channel of the bridged pair has ~1/2 of the total voltage across the bridged pair.

[kmarei]

ok i changed the two output transistors for the bad channel (ch2)
and the 3 resistors
this is what i get when i measure voltage acorss the 5 channels

ch1 0
ch2 0.09v
ch3 -0.005
ch4 -0.008
sub ch -0.015

[kmarei]

Well i changed the 2 output transistors and 2 resistors for channel 2, which was the busted one, with the parts mentioned above

this is the voltage i read across the speaker terminals of the channels

ch1 0
ch2 0.09
ch3 -0.05
ch4 -0.008
sub ch 0.0014

is this ok?
seems ch 2 is the odd one out
prior to repair ch 1, 3, 4, and sub were working fine

i haven't tried with any speakers yet as i already fried one speaker prior to repair
so a little hesitant

[kmarei]

ok i tested a speaker and it sounds good
but when i gave the amp a 1khz sine wave
ch 2 puts out 05v and ch 1 puts out 0.3
is that just because the newer output transistors are more efficient?
i guess i have to change those 2
and might as well do ch 3 and 4 as well as they are all rated at the same power