Newbie Soundstream ref 604 repair

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#26
Perry Babin said:
If one 5632 was hot and the other (for the other 2 channels) was not, the hot one is likely defective.
Click to expand...

So it is actually a TI NE5532AP. Should I go back in with the same thing? Replace both? Or is there an upgrade op-amp that would fit? Started reading on upgrades but my ignorance quickly overwhelmed my interest. Any opinions?

Also is there any other work to do while I'm in there?

Michael
 
#29
The differential transistor rarely fails outright.

With (virtually) all electrical components, their electrical characteristics change as they age. This happens to the two 'matched' transistors inside the differential transistor. If they changed in precisely the same way, it wouldn't be a problem but they often change in slightly different ways so they become less perfectly matched and become incapable of holding the DC offset to 0.000v.
 
#30
I'm having trouble finding the differential transistors. Are they called something else?

Should either of the transistors in question (5532 or diff trans) be replaced in pairs?

The parts are cheaper than I expected so I want to do everything that shouuld be done while it is on the bench.

Thanks again!
Michael
 
#31
If separate transistors are used for the differential pair in a differential amplifier, they should be replaced at once. This amp uses a dual transistor so replacing one part replaces both transistors.

Does your differential transistor look like the one in the photo I posted?

Where are you buying your parts from?
 
#32
JandR has the whole boards still and the two different possible dual transistors. I also have some of both but this is most likely only causing his slightly higher then normal DC offset. vertical board Pin # 7A and 7B are the input to the diff transistor. Just look for a 100 ufd cap on the main board and lift it on its positive side and you can input a signal directly to the channel to test for clean undistorted signal out of channel.
This would rule out the channel completely as the source of no signal thru the channel. Watch your drive level testing the channel like this, a little signal goes a long way here.
 
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#33
Have you had the whole pcb out yet?

With GREAT care, do so, and resolder those upright pcb's (both sides of the upright pcb) where they attach through the main pcb .

The soldering here 'cracks' and causes intermittencies.

The few millivolts you have across the outputs is nothing to worry about. The differential (or long tailed pair Differential amplifier - Wikipedia, the free encyclopedia) very, very rarely go wrong on these amps, even after a catastrophic failure of the output stage.

Do you have a scope? If so, apply a signal to the amp, with no speakers connected, and flex those upright pcb's, i suspect your sound will return.

Are you using any BTL boxes? I have had these fail before.

Percy.
 
#36
1moreamp said:
JandR has the whole boards still and the two different possible dual transistors. I also have some of both but this is most likely only causing his slightly higher then normal DC offset. vertical board Pin # 7A and 7B are the input to the diff transistor. Just look for a 100 ufd cap on the main board and lift it on its positive side and you can input a signal directly to the channel to test for clean undistorted signal out of channel.
This would rule out the channel completely as the source of no signal thru the channel. Watch your drive level testing the channel like this, a little signal goes a long way here.
Click to expand...

Hmmm! The learning curve stays steep. I'll get my workspace clean and see if I have the nerve to try this. I want to get this as 'back to new' as possible. Thanks for the guidance.

Do you have a link to this J and R? Still need a good place to get parts.
 
#38
percival007 said:
Have you had the whole pcb out yet?

With GREAT care, do so, and resolder those upright pcb's (both sides of the upright pcb) where they attach through the main pcb .

The soldering here 'cracks' and causes intermittencies.

The few millivolts you have across the outputs is nothing to worry about. The differential (or long tailed pair Differential amplifier - Wikipedia, the free encyclopedia) very, very rarely go wrong on these amps, even after a catastrophic failure of the output stage.

Do you have a scope? If so, apply a signal to the amp, with no speakers connected, and flex those upright pcb's, i suspect your sound will return.

Are you using any BTL boxes? I have had these fail before.

Percy.
Click to expand...

Thanks for the reply!

I have had the board out. No BTLs ???

I do not have a scope here but may at a friends house. Not that I'd know what to do with it anyway.

I can appreciate that the upright pcb connections might need attention but the op-amp is definately showing the weird oscillating vac on the channel 2 pins. Also shows signs that it has been quite hot (markings are cooked off) and gets hot during testing.

Would it be safe to assume the solder used was good ol lead solder? I'll go over the upright pcb connections for levity.
 
#40
remoteaudio said:
Hmmm! The learning curve stays steep. I'll get my workspace clean and see if I have the nerve to try this. I want to get this as 'back to new' as possible. Thanks for the guidance.

Do you have a link to this J and R? Still need a good place to get parts.
Click to expand...


Perry already posted the ebay link to JandR, just look at this item number and you will see who is selling the part. This fella use to work for SoundStream. He is local to me about a hours drive, and a very good friend also. Absolutely no doubts when dealing with Jaime🙂

Differential transistor on eBay:
380148879173
 
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