STK3102 driver, replace with TO-220's...could it be done?

Bassblaster

Super Member
Im currently working on a Sansui with an STK3102 for the driver, since the thread i posted on it is mostly dead i would make a new thread. Is it possible that IC could be replaced with discrete parts??
i mean all i need in supply voltage, signal in and signal out, Right? this would be highly experimental but the Sansui i have is pure BPC and worth nothing so it can be my guinea pig. it would be neat if i could replace it with $5 of mouser parts

STK DATASHEET - http://pdf.datasheetcatalog.com/datasheet/sanyo/STK3122.pdf
My dead Sansui thread - http://audiokarma.org/forums/index.php?threads/a-1100-60-khz-oscillation.771546/
 
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Maybe more than 5 D's worth but it can be done. There was even a thread or post around here at one time but I can't seem to remember what to look for, but I distinctly remember pics showing an output STK module that was hacked and replaced with conventional TO-220 outputs.
 
I think you would need also a bias circuit. I think it is part of the STK.

I do think a lot tonight, don't I ?
 
Maybe more than 5 D's worth but it can be done. There was even a thread or post around here at one time but I can't seem to remember what to look for, but I distinctly remember pics showing an output STK module that was hacked and replaced with conventional TO-220 outputs.
i know of rsc16's STK-0050 and 0080 replacements. and how 97% of lower power STK packs can be replaced with TDA chips.
Ive seen that exact site before. but im talking like removing the STK chip and replacing it with a small blank PCB with new parts on it not just replacing the dies on its inside.
 
I think you would need also a bias circuit. I think it is part of the STK.

I do think a lot tonight, don't I ?
there is a separate PCB with bias adjustments on it...wonder if it would be affected by it not having its STK pack.
 
Thats where it gets interesting. you have the STK driver itself and a separate driver PCB that has the bias adjustments on it. If i were to build a small board with new parts to replace the STK pack, would the driver board be affected. Someone who knows more then me can look over the service manual if they want. its a sansui A-1100. the BPC special
 
You could reduce it to as few as six (3 per channel) but each one you eliminate you take a hit on performance. And you will have to do some intelligent guessing or trial and error to get the stability right. My 2 cents...
 
You could reduce it to as few as six (3 per channel) but each one you eliminate you take a hit on performance. And you will have to do some intelligent guessing or trial and error to get the stability right. My 2 cents...

AT FIRST i think the transistors on the new board can be MJE15032G and MJE15033G. but what about a differential pair or negitive feedback?
Now whats the 3rd transistor with your idea for? and where does it go in the circuit i can add it to my schematic
This is gonna be fun
 
The STK3102 is input and VAS (Voltage amplification stage), not an output stage (like the 0050 and 0080). So a 3 transistor circuit would be a differential pair and a voltage gain transistor. The eliminated transistors are the current sources (2 transistors) the current mirror (2 transistors) and eliminate the cascode transistor. You would add a bootstrap capacitor to get the distortion to a reasonable amount.
 
Okay now we're making progress. looks like i can use the MJE15032G and MJE15033G. what about that 3rd transistor and where the bootstrap capacitor would go. if only 4 parts pre side this could be knocked out in a day.
 
The STK3102 is input and VAS (Voltage amplification stage), not an output stage (like the 0050 and 0080). So a 3 transistor circuit would be a differential pair and a voltage gain transistor. The eliminated transistors are the current sources (2 transistors) the current mirror (2 transistors) and eliminate the cascode transistor. You would add a bootstrap capacitor to get the distortion to a reasonable amount. Boot strap cap - + end would go to the output (middle of two emitter resistors) and the minus end to the junction between R3 and R4 on the little drawing.
 

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The STK3102 is input and VAS (Voltage amplification stage), not an output stage (like the 0050 and 0080). So a 3 transistor circuit would be a differential pair and a voltage gain transistor. The eliminated transistors are the current sources (2 transistors) the current mirror (2 transistors) and eliminate the cascode transistor. You would add a bootstrap capacitor to get the distortion to a reasonable amount. Boot strap cap - + end would go to the output (middle of two emitter resistors) and the minus end to the junction between R3 and R4 on the little drawing.
i think this is starting to come together but im still missing lots of connections and values
What about the driver transistors?
EDIT:I See you updated your pic. let me update what i got down here
EDIT2:
upload_2017-5-30_0-37-17.png
the collectors of the MJE's are most likely going to the supply rails (+/-70V) Do the other transistors need rail power? it doesnt look like it from here...Q2's base is still open and we have to figure out these resistor values. that will be the hard part.
 
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