Cheap power for sale!

[Elite-ist]

No , those are MT 200 form output transistors. An STK module has a lot more leads and is a complete amp other than just outputs.

Got a couple pairs of those in the parts drawer.

So, the STK module would be centered in the power amp board?

Nando.

In your pic, it's that chip to the far left with the metal backing on it.

Thanks, Jerry and Lee. And that is why amps with STK modules can make good power at low distortion figures?

Nando.

 

[jbeckva]

Nope, basic input Op-amp there Nando. JRC 4560--good stuff. STK's are the modules the SmaLLER PIONEER receivers used instead of a completely discreet build.

Hmmm... So I pulled out a SM for the A1100P, and I have a few parts here. First is the main "amp" IC which is a STK3102-2A. Says it's a power amp and whatnot, but I also have a single pair of 2SC2581/2SA1106's for each channel on the heat sink. Seems the design uses both the STK IC and some discreets?

 

[laatsch55]

The discreets are probably drivers for the big Sankens, or are you talkin the Chip amp??

 

[jbeckva]

Curious .. what's that IC say on the other side of it? I'm gonna gamble and say STK-3152.

 

[jbeckva]

The discreets are probably drivers for the big Sankens, or are you talkin the Chip amp??

Ok, for the 1100 (which is the 100 per I have with the smaller output trannies), it is the 2SC2581/2SA1106's that are the smaller outputs. I gots me TWO amps.. the 1130 (aka 1100, really) is the smaller of the two with 2SC2581/2SA1106's, while the 1200 has the beefier Sankens instead. But both of them in addition to the output trannies do have STK amps.

 

[laatsch55]

3152 a pre amp section??

 

[laatsch55]

Or EQ amps???

 

[jbeckva]

3152 a pre amp section??

No, the 3152 is also one of the same STK power amp IC family, but it's rated output is between 120 and 150, versus the 3102 .. 90 to 100. I probably have the 3152 in my 1200, and definitely have the 3102 in my 1100 (can't see the STK easily on the 1200 unless I really tear into it).

But both of 'em also have the big (or bigger in the case of the 1200) trannies. The STK seems to be voltage-only ... I'm guessing the trannies provide the current gain.

 

[laatsch55]

The 2sc is mainly current gain and DC/DC converter.

 

[jbeckva]

Take a gander at the skeezer.. IC1(a) is the STK.. the heatsinked trannies for that channel are Q4 and Q5. Looks like the dashed line going back via IC2 is the feedback?

 

[laatsch55]

Q2,3 in te signal path are drivers, looks like q2, 3 that are not in the signal path are current limiters. Dotted is feedback, yep. Ic ! looks like V/A stage.

 

[orange]

STK modules??

Darlingtons! Damn.

I had a Yamaha M-80 with a bad channel that would play the good one when I removed the bad C-60. They were given to me to do with as I pleased (so I sold them as fixers for a decent amount, not huge).

That one good channel would spank my speakers then ('03?) like nothing I'd ever owned!

I don't know if they have them, I sure hope not!

 

[jbeckva]

No Orange.. they are NOT Darlingtons.

 

[laatsch55]

Well, McJer????

 

[jbeckva]

Well.. what? McLee...

 

[laatsch55]

You posted a schemo last night, wondered if you agreed with the findings???

 

[jbeckva]

(methinks Lee's expecting me to esplain myself.. oops guess not heheh sorry lee!)

But.. in case anyone's wonderin about these things... did a little research...

STK0050's - Darlington Packs.. yep.. Commonly found in a few Pioneer receivers (and Stu's and Mine's own Sanyo Plus A35 Integrated Amps). Used AS the final/current output stage. Actually part of the family STK0040 (45 watts) through STK0100 (120 watts)

STK3102's - Not Darlington Packs... Hybrid IC Voltage Amp/Driver IC's... Not used as the final/current output stage... needs external bipolars for current drive.

 

[jbeckva]

You posted a schemo last night, wondered if you agreed with the findings???

Oh (heheh)..

Yep. The datasheet for 'em shows a very similar "typical" circuit. I guess the purpose of the IC is pretty much voltage amp plus handling the feedback stuff?

What's interesting too... the one I have in the A1200R seems to have a makeshift heatsink glued onto it. Nando's B.. my A1130, AND another A1200 I used to have a LONG time ago didn't have that heatsink.

As I said... it's really interesting to me how Sansui seemed to use what is pretty much the same "design" across many lines of amps during a certain time period. Furthering my point... both the A1200R and the 1130P also have an external fan that stays off unless a certain temp is reached. If I aint mistaken, Nando's B has one too... just mounted on the inside blowing out.

 

[laatsch55]

Like a generic design with a pick the name you want on the outside eh??

 

[jbeckva]

Like a generic design with a pick the name you want on the outside eh??

Well, sort of... But I can also point out that with the B3000, Sansui did make a few improvements around the design... Take the heat sink design itself, for example. With those amps I have, it really is a relatively small heat sink they have - barely any real metal and just 5 inches across with about an inch wide cooling vanes. But with the B3000 it's a different story... Much more "metal" with that one. Also.. I can't really tell, but perhaps that transformer on the B3000 is larger?