don't know why sir, i always really enjoy watching your videos. I know nothing about repairing. Thanks for showing and sharing your valuable knowledge and expertise.

They have very warm and quality sounds. Also makes everything compact which was a big deal and revolutionary back to 80s and 90s. Also it minimized the distortion as the parts are assembled on a thin board very close to each other mounted on aluminum plate all grounded by the heatsink. They were not cheap back to old days and not expensive compare to individual "quality" transistor. Thanks for this video!

In my teens I built a 2x200 Watts power amp with the STK4050 modules. I never had any issue with this amp surviving my extreme abuse of playing very loud and even shorted it a few times. It has short-circuit and thermal protection in it also.

@12voltvids, thanks for sharing this with us, I remember my old boss replacing these all the time in 80's to 90's stereo equipment, i've always wondered what they looked like inside

Thanks for the peek inside. I've got an old awia that needs some of these moduals but I keep putting it off. Love the sound it has but restoring it will cost more than its worth. One day I'll get around to it 😂

Fascinating. I never bothered tearing one apart before. Thanks.

Thank you for showing this great video! I have several amplifiers / receivers made by Sony that incorporates one of these. As the matter of fact my STR-AV310 uses the STK4182II. I got this receiver from one of the older ladies that was getting rid of some stuff and looking inside someone already changed the output and wrongly (or purposely because they had no original in stock) installed STK4162II. 4162II was not meant to handle the power that the amp was designed so when I get up in volume, the heatsink gets really hot! I repaired electronics for over 30 years and would never replaced higher capacity part with the lower power/capacity. That was just so wrong whoever was repairing it. But as you mentioned, Sanyo's idea was great back in 70s and 80s for coming up with these designs.

I still have an early 90's Technics receiver with these STK's in it. I used it as sound reinforcement in a DJ setup back in the mid 90's. I use it to drive my Bose computer speakers today. So it has had an easy retirement.

This particular STK is one of the most advanced stereo unit produced in the serie. Early units were limited to mono operation and relatively low power. But I can perfectly understand the fact someone tries to replace the failed components, as the level of miniaturization of these 30 year old units is that of the common SMD of today's circuits. It will certainly become much more complex to try that on a new generation miniature power modules. When one of these fragile old modules fails in a 1000$ audiovideo power amp, (you know the policy of most repair shops!), you also know you're in a deep s--t! So why not find a decent and cheap solution that is not a fake or doubtful eBay sourced module?

Never knew there was so much going on in there - I had assumed it was literally just a couple of darlington pairs inside.

That was really interesting, thank you!

Always wondered what was inside them. Thank you

I've come across a forum post on audiokarma where some smart guy designed a pcb with SMD components to replace those modules. If I recall correctly it was a stk3082 or something in that line. I still was lucky to find an aftermarket module to replace a blown one in a Marantz pm52.

amazing video

Technique for taking apart the STK418211 is excellent. It took me 10 minutes and three hand injuries, to open an STK463, before deciding whether to attempt to repair it...even if only for Speaker A....or go for a fancy pants more replacement such as a TDA2793....still unsure (repairing a 1981 Sony STR-VX2L FM/AM Receiver/Amplifier)

Great video

As long as they have a quality power supply feeding them they last a long time. I have a Panasonic SU-380 integrated amp from 1984 that is still working like new

Watching here thank you for sharing

Really interesting video, I expected them to be potted hence no way to repair them. This is good to know as if I ever come across a blown STK module (I haven't yet, must be lucky haha although most of the kit I buy is discrete) then I can at least have a look-see at repairing it. Thanks again for the National/Panasonic CCD battery tip a while ago, M5 battery took a charge eventually and after sitting off-charge ever since it is... Holding a charge, just checked it now! :) Much appreciated man.

I can remember my late father changing lots of these back in the 80's. They used to get bloody hot when driven hard. Most of them got blown by idiots connecting too many speakers or shorting out the outputs. They didn't like it up 'em!!!!!

I got a ton of Sankens nos, along with Motorola driver's and Pre-drivers. Fisher/Sanyo perfected their integrated outputs for their Studio Standard line. Extremely stable, and capable of incredible power.

I've had receivers come in with those black covers blown off, lots of fun, sometimes the same customers over again, can't imagine how high they keep the volume

Pioneer has some of these chips also..they called it the hybrid technology..mainly used in some of their av receivers

Very interesting. Next time a STK7216S power supply module fails in a Sanyo Beta video recorder, I'll take it apart. I always assumed that it would be impossible to dismantle.

Very useful tips.My stk4182 shorted, replaced with 4192 but that too had gone.Thinking of trying with 4231 mk2.Sould I?

I have one of these STK chips kicking around somewhere. torn down of course. Pulled it from a broken stereo. I put power to some of the pins when it was opened and one of the large transistors was faintly glowing. I also have a sharp stereo that when powered on makes a really loud POP and then nothing, no sound on anything, CD, Tape, Aux, radio, nothing. It does output sound from the internal circuits before the main amp because I've tapped the audio lines and made a semi working system but you just need an external amp. Could the STK IC be blown? Are these easily replaced like just buy a new one and solder it in?

STK5481 - a number burned in my mind thanks to Ferguson and VCR's that had them in the power supplies. Pain in the arse

I actually managed to get an original stk4141ii on ebay. No ripoff and working! Couple of years ago

I remember replacing a lot of thoughts, the package or the part book i ordered from had the schematic for it.you could go to like PCB way make new ones with replaceable transistors they will do the surface mount stuff.If you had a need to.

very interesting

One thing I've noticed with amps that use STKs is they have no idle bias adjustment. They must be compensating them somehow.

Interesting video. I wonder if the SanKen modules of the late 1960's - early 1970's were made the same way? I have several new old stock SanKen audio amp modules in my junk box. They required very few outboard components. I was going to make a 4 channel amp back in 1972 but never got to it.

Sir is there any way to check these stk ic is working or not without opening these ic , I'm not basically an electronic guy , but I have an old Sony music player , which does not proving any output audio signal ,so I got some suggestions to check those stk ic, the inside ic is too stk 4182 ic as same as yours

🙏🙏🙏🙏🙏🙏please help🙏🙏🙏🙏🙏🆘 Sony stk 418 211 ic ..... How can I test the stk ic I de-soldered from board🙏🙏🙏🙏🛹🛹🛹 I don't know.....

Nowadays they still use amp modules, but they just look a bit different. On chip amps like the LM3886 or TPA3116 have DIP package variants that can give up to 50W, which is sufficient for most small things like soundbars and Sonos speakers.

It will be very helpful if you make video on how to check fault inside stk module and transistor replacement on stk module. In 2018 my Sony MHC-RG290 with Stk403-100 gone bad (it also had similar design and 4 transistors inside )and replacement was not available so it is still sitting in corner of room.

Dave does a bad STK always put a receiver in “Protect Mode”? I have a kenwood with audio going in on the input pins, but nothing coming out the output pins..

if that part is damage then not open the system on??? my aiwa is off not open...power off

Thank you so much for this video. I'm so excited to see a bigger representation of that, what I saw inside processors or micro-chips (but a way way smaller) under powerful microscope. It's like an electronic porn :) greetings from poland

How do you test these to see if they're good, do you just pop them open and look for damage?

These modules are a PITA, apart from audio output, they were used in rear projection TV's. Bloody expensive to replace, if you can actually find one!

Didn't they use these heavily in CRT projection televisions? I seem to remember replacing a few ages ago.

polish gml series was similar to stk's the biggest difference was in the 80's we had schematics for those and they were build from off the rack transistors so 80% of blown ones were fixed by the shops instead of replacing the modules :] pland was wierdthis way

First thanks a million for opening up an STK unit - its great to understand how they function. Although I get what manufacturers were aiming at it is a Disaster for the average vintage user to have an STK unit blown. You could have paid massive money for a vintage Marantz/ Sansui model and it's dead. I try to keep a list of popular vintage amps with STK units in them so I can STAY AWAY.

I took one of these apart a long time ago (not this specific part #, but a similar-looking hybrid module); it had a ceramic substrate instead, with sh*tloads of thin-film resistors, a few transistors, and an IC die. I think it may have been an early ECM/PCM from an automobile. It would be interesting to do a shango066-style “resurrection” video to see if you can get this module working again, as well as a reverse-engineering of the one good channel. Looks like the input was A.C. coupled (I see one SMD capacitor in each channel) with the remaining stages being D.C. coupled. This would explain why the dead output took out the driver stage, too. The set should have had a speaker-protection circuit (if it didn’t), or the speakers would be the next things to go >pop

Parts Express and E-Bay sells a Class D replacement. $26.50 each. The old modules needed fan cooling. Search "Sanyo STK module replacement".

Sanken made these as well.

Major reason to use those was to cut assembly cost, as you put in a single near idiot proof module, and used the manufacturers application note as is, and your product would work. No need to have a hundred similar looking resistors and semiconductors to place by hand ( remember most of these cheap sets were hand assembled, from component insertion to final assembly, with little automation) along with all the possible insertion errors, instead you have a dozen or so external parts only, some coupling capacitors and one module, 2 minutes total including soldering per board and heatsink. Modules are cheap in bulk, probably less than the cost of the individual components to the small assembler, as the manufacturer of the module ( mostly Sanken) bought bulk bare dies, and bulk packs of resitive paste, so they had a low cost per module for parts once the design was set. Single screen or two for resistors, probably for different bulk resistance pastes, a screen printed solder resist, some solder paste for the individual dies, then toast the module to both cure the resistors and solder the dies, and then wire bond, test and pack. Mostly either multiple modules at once, or semi automatic machinery, all driving the cost down, and of course sold to a lot of small end OEM assemblers in bulk, so even making a cent per module nett profit is worthwhile, plus the lucrative low volume service market as well, where you could sell the module in low number for ten times the cost, equalling the profit from any small OEM easily.

Are those four squares, the power transistors are on, made of silver ?

Hello. An interesting video. Could you use higher power stk's in place of lower powered ones if I couldn't get the exact ones needed? Thanks.

anyone knows who repairs STK's on yt?

These can sound really bloody good i tell you, depends on the rest of the mainboards circuitry, but yea, some sony all in 1 hifis that have these modules sound absolutely amazing, but you have to keep them cool, thats why they fail. a simple 500rpm 80mm fan will do the trick, the sony MHC-551 is the best sounding mini system ive ever heard to date

There was a time when i also tried to fix those amps and measure and change the components inside with SMD but this is not a task for everyone and not worth it if you not doing it for yourself.

The ones with a letter B stamped on low right face side and had a charcoal black plastic were better in my opinion cause I believe they were OEM parts.

Panasonic, technics, Pioneer, Panasonic, sony used these type of hybrid modules in there mini hifi systems.

A neat idea but they needed protection in every amplifier they were in, san-ken were similar. Maybe the transistors were under rated or not throttled back to protect them. Yet the ones in t.v's seemed more reliable. I got ridd of many amplifiers because they had the "Death modules" in them. Multiple power regulator modules in vcr's were not too reliable eather. Pushed too hard maybe.

Can we replace that kind of transistor

i have always wondered if it would be possible to replace this modules by conventional SMD transistors (maybe using a custom pcb and heatsink). Instead of putting effort into imitating original modules, Chinese manufactures would get way more money if they coud offer an affrodable and maybe more reliable replacement solution

I took STK to mean Shit That Kills - by the time they popped, couldn't find replacements.

I have one of those in a technics ST-CA1060, I did come up with f61. Then would shut down.. this was after not being powered up for 10 years.. it worked ok when it was put to bed tho.. now the fault has cleared itself.. must be a capacitor? it works again.. but if I was to start using it, I bet then its days would be numbered

if you force a short the power transistor will produce light just before meltdown.

they don't like pushing alot of power and are very sensitive to the load applied to them

A friends electronic organ got hit by lightning , this was about the only item that failed, organ got repaired with tack on non STK amp modules , organ has ok sound maybe slightly under powered now though.

Someone could make a mint if they designed a modern drop-in replacement for these.

can you help me sir

Now we see it in clear view what's inside. Thanks Dave. Listening over Sennheiser HD58X, not bad, just too much low mids for my taste and as flat-transparent as HD600. Way cleaner than ATH-M50s but with out their low bass. People at DIYAudioheaven are awesome if someone is into headphones. diyaudioheaven.wordpress.com/

There's natning wrong if used properly stk. They Ware very good. SANYO did a good job. Butt yes they did blow. I have replace them befor.

planned obsolescence component

They sure had good sound though. But damn they fail...

Helo 12voltvids I am HUGO of Mexico city you can wright subtitules in spanish a your pictures

those STK Amplifiers is pore, they week and work only 6 ohm well i replays those with TDA 7294 is Better "АВ" class

N channel out stage darlington, ???? Struktures this stk ?