It looks like you might be able to replace all the transistors in that fake STK with real ones. It looks like you could solder DPAK’s where the power devices go (Scrape the dead ones off). It looks like they omitted emitter resistors (bad move), but you could put those in between the emitter lead and the PCB. Mount the thermal diodes directly on the tabs of the power trannies with epoxy (leaded 4148’s). See, you can do better than the idiots that designed this.
I am going to update my own STK story. But let me give you a heads up. As you seem to be struggling.
If you have an AMP with the STK IC on it. This is what I would advise.
STKs are used in amps two ways one way is single STK IC. The other is as differential ICs. Testing differential ICs are a nightmare but can be done with any cheap scope. Just invert ch2. Then goto math function and do a CH1+CH2 and you can tesit.
1. Cut it open if its something simple like a burnt track or wire fix it. Else throw it. And remove the word STK from your mind.
2. Forget about buying a new STK 99.99% of the time your going to get a fake. Made is somebody backyard in china or India. And its not going to work. Or last. The sound Quality also bad.
3. You want to get your hands on a TDA7293 or a TDA7294 they are cheap and sold as 2 separate modules or a single module. Based on what kind of amp you use. Tap into the first STK IC for your input. Then take the output from the TDA and feed it to the output of the second STK.
The TDA is class a/b amp. Just more modern. So your sound should not be impacted too bad. Plus you get to keep all the pre-existing power supply / tone / bass / ballance / volume knobs.
4. The TDA modules can handle upto 50 volts But they do need a good heat sink.Most guys use the STK heat sink and it works fine.
5. Many guys claim to have built their own STK ICs on boards we have one thread here where the gerber files and bom has been shared. But I could not figure out how it would work in my setup i.e. does it replace the 2250 or the 3240. And if it does replace one of them What do I do about the other.
There is another guy on Amazon dot in who is selling a similar STK IC but again no info. Search B Tech audio.
STK IC price is based on demand so right now in India the 4141 is popular as is the 4191 these are being sold for Rs 150/- i.e you buy an amp board / kit from some guy and you blow your STK he will replace it for Rs 150/- which is like 2$.
Your chasing a rabbit if you think you can find an original STK. Nobody will sell it. I spent one month chasing down a pair in Russia then got it listed on ebay usa and had a relative bring it back to India. Took me close to 6 months. And it was nothing but some junk made in China.
They do not last. They take out your speakers. The original STKs would last 20-30 years the replacements pop and smoke if you look at them sideways.Also they have a nasty sound when you power on the amp. Im not sure what happened in my case but the speaker dia got fully sucked in and then made a pop sound as the coils shorted. After that no audio from one side. We found that one chanell had blown on both STKs. You should get a speaker protection circuit it wont save your amp or STK but it will save your speakers.
There are companies in Delhi who are no making everything you get on aliexpress for half the price. If you want links message me. I dont want to upset anybody here or look like Im promoting any company.
My new most hated word in the world is STK lol. If you can find an original circuit for the STK I can throw together a board in egal and get it made. But it seems like a lot of work. For such an old zero value amp. I have the schematic from the data sheet but no values. For the components.
If you find the TDA has poor bass. Which is a common complaint. Then go for a Transistor based amp. 5200/1942 you get the boards for like 2K this even comes with its own bass/treble/mid knobs. And if anything blows you can replace that component.
I will have a look at this circuit you have purchased and see if I can help or use it myself. But I doubt it. The TDA route is well tested / cheap / and just works. My brian is sleep deprived will be back once I catch up on some sleep.
If you have an AMP with the STK IC on it. This is what I would advise.
STKs are used in amps two ways one way is single STK IC. The other is as differential ICs. Testing differential ICs are a nightmare but can be done with any cheap scope. Just invert ch2. Then goto math function and do a CH1+CH2 and you can tesit.
1. Cut it open if its something simple like a burnt track or wire fix it. Else throw it. And remove the word STK from your mind.
2. Forget about buying a new STK 99.99% of the time your going to get a fake. Made is somebody backyard in china or India. And its not going to work. Or last. The sound Quality also bad.
3. You want to get your hands on a TDA7293 or a TDA7294 they are cheap and sold as 2 separate modules or a single module. Based on what kind of amp you use. Tap into the first STK IC for your input. Then take the output from the TDA and feed it to the output of the second STK.
The TDA is class a/b amp. Just more modern. So your sound should not be impacted too bad. Plus you get to keep all the pre-existing power supply / tone / bass / ballance / volume knobs.
4. The TDA modules can handle upto 50 volts But they do need a good heat sink.Most guys use the STK heat sink and it works fine.
5. Many guys claim to have built their own STK ICs on boards we have one thread here where the gerber files and bom has been shared. But I could not figure out how it would work in my setup i.e. does it replace the 2250 or the 3240. And if it does replace one of them What do I do about the other.
There is another guy on Amazon dot in who is selling a similar STK IC but again no info. Search B Tech audio.
STK IC price is based on demand so right now in India the 4141 is popular as is the 4191 these are being sold for Rs 150/- i.e you buy an amp board / kit from some guy and you blow your STK he will replace it for Rs 150/- which is like 2$.
Your chasing a rabbit if you think you can find an original STK. Nobody will sell it. I spent one month chasing down a pair in Russia then got it listed on ebay usa and had a relative bring it back to India. Took me close to 6 months. And it was nothing but some junk made in China.
They do not last. They take out your speakers. The original STKs would last 20-30 years the replacements pop and smoke if you look at them sideways.Also they have a nasty sound when you power on the amp. Im not sure what happened in my case but the speaker dia got fully sucked in and then made a pop sound as the coils shorted. After that no audio from one side. We found that one chanell had blown on both STKs. You should get a speaker protection circuit it wont save your amp or STK but it will save your speakers.
There are companies in Delhi who are no making everything you get on aliexpress for half the price. If you want links message me. I dont want to upset anybody here or look like Im promoting any company.
My new most hated word in the world is STK lol. If you can find an original circuit for the STK I can throw together a board in egal and get it made. But it seems like a lot of work. For such an old zero value amp. I have the schematic from the data sheet but no values. For the components.
If you find the TDA has poor bass. Which is a common complaint. Then go for a Transistor based amp. 5200/1942 you get the boards for like 2K this even comes with its own bass/treble/mid knobs. And if anything blows you can replace that component.
I will have a look at this circuit you have purchased and see if I can help or use it myself. But I doubt it. The TDA route is well tested / cheap / and just works. My brian is sleep deprived will be back once I catch up on some sleep.
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1) I and suspect many don´t have experience with your Hypex module, never saw the schematic, you only show bits of screen capture, but is a COMPLEX amp, my advice is forget it, at least for this job.
Forget about modding power supply, etc.
Simplify your life, and work with what you have.
2) you have: an otherwise working amplifier, +/-30V power supply, heatsinks, and formerly a +/-30V fed Class AB amplifier happy with that supply, so get an equivalent that fits in available space and can be bolted to heatsink.
Please post a couple amplifier "guts" pictures, one showing all of it, plus a closeup of the heat sink area.
New module must fit there.
There are many Class AB amps, chipamp and discrete that will work there, problem is physical dimensions.
Again, try to make the task as simple as possible.
LM3886 based amps "would" be a perfect fit, but by now all are fake, or suspect.
Maybe real TDA7293/7294 modules are still available, simply because there is lower demand for them, those would be fine too.
Forget presumed or claimed "differences" , as in "xxxx has poor Bass, yyyy is not flat to 300kHz", etc. ; ALL chipamps are clean and ruler flat at audio frequencies, real people can´t tell one from the other by ear, so all work fine.
You are not building an amp for a contest for a prize but reviving an old amp you already have, let´s be realistic.
Forget about modding power supply, etc.
Simplify your life, and work with what you have.
2) you have: an otherwise working amplifier, +/-30V power supply, heatsinks, and formerly a +/-30V fed Class AB amplifier happy with that supply, so get an equivalent that fits in available space and can be bolted to heatsink.
Please post a couple amplifier "guts" pictures, one showing all of it, plus a closeup of the heat sink area.
New module must fit there.
There are many Class AB amps, chipamp and discrete that will work there, problem is physical dimensions.
Again, try to make the task as simple as possible.
LM3886 based amps "would" be a perfect fit, but by now all are fake, or suspect.
Maybe real TDA7293/7294 modules are still available, simply because there is lower demand for them, those would be fine too.
Forget presumed or claimed "differences" , as in "xxxx has poor Bass, yyyy is not flat to 300kHz", etc. ; ALL chipamps are clean and ruler flat at audio frequencies, real people can´t tell one from the other by ear, so all work fine.
You are not building an amp for a contest for a prize but reviving an old amp you already have, let´s be realistic.