SoundStream 700sx w/bad transistors

[AKHeathen]

the bands would be red-purple-silver-gold. it's a pita sometimes when they have seen heat over time. i've tried all different kinds of bench spot lighting to read old resistors better. right now the halogen35 seems to be doing ok. anyways, i would start by pulling the 2 driver boards and checking the circuits on them. chances are the drivers are damaged. it looks to use the same as the 500, where the 1000 needed to have some paralleled on the board. it's also nice to make sure the mounting connections are fresh for the driver boards. also, check q35 and q21 for damage as mentioned, all that q59 does is activate with a big enough voltage drop across one gate resistor, then 55 is tied to both 55/56 and (+) rail voltage, then run through a resistor and diode to the (+) lower regulated voltage. i would check all those parts for damage

[jeanious2011]

Thanks for the info.

The boards (both FEB and pre-amp) look like they have solid good connections. Is there any way to check them? Or what usually goes bad on them? I hate smd compenents but have work with them in the past with no problems, just a PITA when you have to make sure the SMD parts dont move with the touch of the iron, lol.

[AKHeathen]

i used my fine tiped leads and did a contiuity check from one end of the solder on the preamp board to the other end of the connection on the main board. i could not really even see the broken connections, but i was able to see tiny lines when looking real close. if you pull the preamp boards, you can isolate more of the circuits and components from each-other.

[jeanious2011]

Checked the emitter resistors and they all read 0.4ohms. Then i checked Q56 and it was BAD, it looks perfectly fine but after testing it it was bad also. So now am worried if both channels were bad after repairs.

Then I checked one transistor (Q37) and the collector pin wasn't making proper contact, wasn't solder properly (by me, what a dumbass, lol).

So now my question is should I just go ahead and replace all the TIP102/107 on the Right channel (the ones I left on the board)?

Darn it I should of just sold this amp for parts a long time ago, spend 24 bucks on transistors already plus a few resistors and now it looks like another 20 bucks in parts. Next time I know if i purchase a broken amp I better get it real cheap otherwise pass on it.

[AKHeathen]

lol, tell me about it, i spent $75 on an order of 50ea. 107/2's i really like these amps, though. did that diode check out ok? you should be able to leave the q56 out of the circuit for testing the right channel for problems. the circuit should run from the left channel just fine. check for shorting on pins 5;6;7 on the tl072. the q56 was likely just damaged when q55 went out. if the right channel outputs read fine, i wouldn't worry about replacing them just yet.
*couple typos on my post #11 "check q35 and q21 for damage. as mentioned," "across one gate resistor, then 59 is tied to both 55/56 and (+) rail" fixed

[hollbrow]

I just got my 700s back operational today. Changed a lot of parts- PS fets, driver trans, gate res, rectifiers, and a controller IC. I got my parts from Jaime- great guy. And much thanks to Perry for his tutorial and spot on e-mail advice. I bought spare parts & some parts I turned out not needing but good to have as I have several of these old Soundstreams. I'm not doing this to save money- I enjoy knowing I fixed it myself and learning about these amps. I think I have read everything on this forum about these amps- at least what I can find by searching. There is an awesome amount of information on here that I am grateful for also.

[AKHeathen]

good deal man.... if you ever want to do a deal on some, i'm always interested. i guess you could say i had the kicker zr's, ssref's, and then directeds imprint on me about what real clean/solid power is. i even have my original 1000sx sitting on the bench, and i sold it a year or so after buying it brand new. i still have tons to learn myself, and more equipment to buy to get set up, but i'll learn every circuit in these amps by heart if it kills me, lol, and yes, perry is an awesome wealth of knowledge. lives and breathes this stuff, and never wants anything back.

[jeanious2011]

I'm also a do-it-yourself type of guy. But ofcourse need some help on the way. Perry has helped me a lot, I have his tutorial also and very grateful. We'll see if Arrow allows me to register so I can get the tip102/107's real cheap, 24 would cost me about 28 bucks at mouser and at Arrow 24 for 8 bucks thats crazy.