Soundstream MC245 repair

[dhamia]

Hi guys, got hold of an MC245 5 channel Soundstream, tested and all full range channels work great, however the sub channel has some fried components.

The sub channel still powers up but no sound, can anyone tell me what the missing components are?

previous owner had removed the slider switch from bass channel and soldered in a couple of links! don't know if this caused the fired components.

The board looks fine and everything else works great, would love to restore this one, the sound quality is the nicest soundstream iv'e heard and I've had a few.

Any help appreciated thanks

 

[Perry Babin]

If no one has the same amp to tell you precisely what you need to know, clean up the area with acetone (or alcohol) and cotton swabs to see what's actually damaged/missing.

The sub channel should be very nearly identical to the other channels. Find the corresponding components in one of the other channels and by process of elimination, find what's missing.

 

[borisgermany]

photos for your problem

if you need more details, you can contact me
greets boris

 

[wadest]

MC245

dhamia, I designed that amp. I am sending a schematic for a MC300. The photo showing the bad parts appears to be the power amp drive circuitry. The circuit is identical to the one in the MC245. You should check the output transistors. they are TIP 142's and TIP147's. There is a small rectangular transistor with 6 legs. That is a differential pair transistor. I have them here but I'm not sure how much shipping would be. Check mouser.com a Fairchild FMBA06 might work. They are $0.57 each.
Let me know if you need more help.
wadest