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srnrox 6th December 2012 10:06 PM

soundstream rubicon 1.1600d transistors??
I have blown output transistors and possibly the inputs too. I was wondering if anyone could suggest to me what to replace them with soundstream wont release any specs on the original ones im a noob at this its my first repair haha the output transistors are irf p849d

srnrox 6th December 2012 10:49 PM

I think i may have been reading the wrong numbers lol sorry it says :b31n20d

indianajo 7th December 2012 01:56 PM

Having private label transistors is one of the tricks of the trade to force you to take your unit to an authorized service shop that pays the manufacturer. the numbers you have probably mean about nothing unless you have a cross sheet for soundstream. The only company I know that gives away the cross sheet is Peavey, that is why I buy their old broken stuff.
If you have a schematic diagram and can determine if they are FET's or BJT's, good. If not, see if any survived and see if the base lead or gate lead has a .6 v junction to the E or C, or is open. Use a humidifier to avoid static blow up if it is a fet. The gate or base lead is the one that leads back to the to220 driver transistors or the driver IC. A fet will have an open gate unless it has a zener gate protection diode.
Then determine the rail voltage. You can read the voltage off the big rail capacitors, usually a little less than they say. Your Vceo(bjt) or Vdss(fet) has to be higher than that. Determine the package style. The look through the selector tables of a vendor to find some of those. Look at the datasheets and see if any are designed as audio amplifiers or head drivers. The higher the safe operating area current, the better the part IMHO. Higher gain units are safer to buy than lower gain units, if you don't know anything. Almost all amplifiers since 1970 have been dual rail voltage units, so you need equal number of NPN and PNP parts, or NMOS and PMOS parts, usually. Fets, enhancement mode is pretty standard. Fets, there are some particularly wonderful hard to get ones involving special gate technologies, you probably don't have those.
If you can figure out what package you have I mightmake some reccommendations on BJT transistors, but I know a lot less about FETS since my stuff is too old to have them. To figure out the package, download some datasheets and look at the package diagram and see if you have that one. Common are TO220, TO3, TO247.
Check your emitter resistors too, they usually blow also. Also the driver transistors, and a bunch of other stuff. I had to replace about 100 parts in my PV-1.3k, driver & predriver transistors, IC's, diodes, blown resistors, even some blown ceramic caps that showed open (as a cap should on an ohmmeter). I even had a couple of PWB lands burnt off.

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