You gotta love the chineese for making counterfeit electronics. This is true of a lot of products including the tools we use today. Better to mimic these components and make it better than the original using discrete components.
Depending on the circuit, I've replaced STK IC's with LM series IC's. Of course, you have to do both channels and some modification, but alot easier then dealing with fake Chinese parts.
I'm glad my Yamaha AX900U amplifier has discrete amp components. A/B transistors easily replaced and available. My amp was made in 1987, and still strong.
Interesting. It's a tough thing to find valid parts for most anything electronic - I can start a ramble on smartphone parts, automotive parts, computer parts, just about anything is knocked off and of truly substandard quality. I been repairing electronics for 25+ years and have witnessed the decline personally on the demise of repairable goods, and the what I can swear is purposely made scrap/junk replacment parts that are of ill fit, and if they work its a miracle and the repaired item will suffer from degraded performance at best. NOS , or a parts unit is the way I go these days and usually its just acquiring units for parting out in most cases to get a vintage item working correctly once again.
Even a lot of output transistors are now fake Chinese counterfeits. So even a receiver or amp with a discrete output stage can be challenging to repair with original parts. And some designs have stability issues with substitute transistors. Into an 8 ohm resistive load on a test bench everything might look good, but drive the amp to clipping into a real world reactive load (speaker) and it may oscillate when it clips which, at best, might destroy tweeters and possibly cause the amp to fail again. Modern transistors tend to be higher speed and higher gain both of which can contribute to stability problems. A lot of people doing repair work don’t understand this. In order to get good specs, a wide bandwidth, fast rise time, etc, amps especially from the 80’s often use massive amounts of negative feedback and as small as possible compensation caps along with small output inductors. Putting substitute transistors into these designs skews the phase shift in the amplifier and, under some conditions, negative feedback can become positive feedback with often disastrous results.
I remember my first experience with counterfeit transistors. It was servicing a Kenwood super eleven. The devices were bogus, and as soon as an inductive load was on the unit and any current was pushed through the amp, there was a bright flash and a fire. The amp had oscillated out of existsnce
hi i stumbled across this video and this channel after buying a counterfeit and defective svi module for a technics/matsushita amplifier..i am also a vaccum tube tv hobbyist so i have already subscribed. cheers
I ordered a counterfeit module a while back in an attempt to repair an old Technics amp. As soon as I went to adjust the bias on the channel the protection relay clicked on - module dead. The manufacturer sent me another one and this time I barely turned up the bias pot and it's been working well. Still junk though.
The fundamental idea behind STK is fine but units using these things certainly present a service challenge. I've also been caught out with fakes. Good luck finding one.
Could you please share with us what the fundamental idea of the STK series would be? I'm not entirely sure since I've some units appearing in hifi equipment made by reputable brands (Pioneer for example) ,and yet people in the diy audio community find it to be not so great in terms of audio quality and remark their fragility and tendency to fail.
I used to have a Realistic STA-130 that killed the RH speaker due to short in the STK chip, split supply amps using module chip are an accident waiting to happen, I prefer discrete transistor amps when it come to split supply format, The Dynavox CS-PA1 has a TDA chip but it's single ended capacitor coupling, I recently bought the MT-50 model and found it is split supply, also loud hum regardless of vol knob setting (3x louder than the mild hum from the CS-PA1)
interesting point! Even a lot of transistors are fake (if you go for original). When buying amplifiers to repair I avoid module-based precisely because of that
Yeah, I got burned by an ebay "reputable" distributor in Florida that when I complained the the part they sent me wasn't any good said. "We only said it was an official manufactured item (something like that). We didn't say it was the same as vintage items with the same number. "
Interesting video you show there...I recently repaired a Sanyo DCA611. It uses 2 STK0059 IC's. Luckily one was burned and I ordered one from Germany. Certainly the weight point you mention there is true. They weigh less, but the plastic case does not go thicker or above the aluminium heatsink. I just don't know what to expect. The IC bought from Germany worked and still works but judging from your video, don't know for how long ? May be I can use the stk0050 replacement using real transistors and board with aluminum as demonstrated on some video here. Thank you
Sanyon semiconductor original maker of STK have been closed long time ago. If you want the original find used one. All new STK in the markets are for replacement and not original
I got conned by a distributor on E-bay. So I know what you mean. I have a Sony surround amp that has something similar as a center channel preamp. Got hosed on a claimed "pulled part" same with the amp transistors that were supposes to be complimentary darlington pairs.
Yes i agree with you about those stk chips I've been replacing a number of them, and it's becoming difficult to get original ones and the copys are bad + low quality.
I actually though it was interesting that someone could build the chip. But yes, you’re right in regards to honesty and reliability…..the chip doesn’t come close to the real chip and it probably should have been advertised that way.
I have some experience with this too. I bought a replacement Darlington STK-0039 "Power Pack" on eBay that was supposed to be original. I could tell it wasn't original because the imprints on the chip were different, the 10 pins were not numbered. I installed one into my Pioneer SX-680 which had a bad channel. It was no easy task- I am not as electronically inclined as you- thermal compound has to be applied. The stereo worked for about 2 hours, then the power pack blew and it was dead again. I was pissed.
Sounds like you have some fault in your pcb lines. Even you buy pure Chinese copy of stk icS, it will still able to handle the same voltage and load. Load is important. Almost all stk series icS are rated for 8ohm load buy they run just fine with 6ohm load. If you use 4ohm load speakers on stk's icS it will blow up in loud and and long run. Lot of people doesn't understand about speakers impedance. Some are parallel 2 speakers in one channel which changes speakers impedance in half. Some time speakers coil gets short and those speakers will make sounds but they are the silent ic killer. First thing you can do is check your speakers impedance with a digital multi miter.
Jordan, be very careful on eBay these days. Since the pan-----, they have closed down there telephone customer service, which had been outstanding. We're forced to send email back and forth to the Seller. Unscrupulous sellers know this and uses the time to run out the calendar until you either give up or the allotted time has expired. Very unhappy with eBay because of this.. I have been an eBay customer since 1999. No major purchases on eBay for the foreseeable future because of this.
Good luck finding an original replacement, I managed to find one a while back from China, clearly it was a used chip, but actually worked fine! I really dislike these modules, apart from amplifier chips, they came as power regulators & convergence chips on projection TV's.
Hi JP. Thanks for uploading these great vids. I've really leanrt alot.I've this denon old AVC A1 amp 240v model which was working faithfully for years. Recently I connected a different set of 4 ohm towers (amp rated at 8 ohms)and it played well.But from time to time, it wouldn't turn on. The display appears to turn on then blinks and shuts down.Sometimes it works great without any issue.Do u know what could be causing this?
Not without seeing it. Could be power supply issue,. Amp going into protect mode from an intermittent fault, cold solder joint, or bad ground. Could also be intermittent amplifier fault
Jordan Pier Thanks for the reply.I suspect the 4 ohm towers may have caused the output trans or driver trans to be damaged. B'cos I hooked up a different denon amp which worked for a while and then shut down too.Both amps are rated at 8ohms.Do u think I could replace just the output and driver trans on the amplifiers to handle 4ohm loads?
I wouldn't go replacing parts. If your speakers are pissing off two receivers, you've got bigger issues. 4 ohm speakers won't do well on an 8 ohms rated receiver, but will only shut it off at high volumes. No easy way to just replace parts to make it work. You need more.output transistors, bigger capacity drivers and bigger rectifier , sometimes even a bigger transformer
Uggghh, I always hated those amp on a chip designs---it's the ultimate in cheap, throw-away technology. I remember those being used in cheap shelf stereos from the 70's/80's, and they went bad often
So, question. If it had been assembled well (proper heat transfer, perhaps not potted) and identified properly as some sort of non-original retrofit device... how would you feel about that? Conceivably you would have no moral issue with it, but would you use such a device?
Do u know if the counterfeits are noticably lighter in weight?..im trying to figure a way to tell if real or fake without takjng apart?.. my real stk 4191 weighs 45g...the real one u had looks lot like mine...fyi the originals are almost impossible to take apart..unless you do a cut out...could you weigh your fake one vs your real one and let me know the weight in grams? if possible.
@@JordanPier thanks a lot im trying to find an original so im asking ebay sellers to weigh theirs..one guy came back and said 45g which is about what my orig is....i dont want a fake....i want high quality orig..my orig lasted 40yrs i dont want a chinese fake that will last 1 week lol
@@JordanPier I need one of those Mr Carlson Lab testers. lol. I bet they are all fakes but I was hoping they were pretty good ones. I wonder if there is a way to cut open and repair an original? I have a dead SVI here.
@@JordanPier ok well when you say considerably lighter can you give me a % is it 10% lighter 20% 30% 40% 50%.....is it substantial or just a bit is what im asking..im trying to buy a genuine and need to have idea what the fake will weigh..do u have a genuine u can weigh..?
I had a Yamaha r-300 with a cooked ig type device(yamaha's stk) and swapped in some tda-7293 in it's place. Extra effort, but sounded fine. That might be the future for these sets unless someone starts making good ones
I have a marantz reciever and a yamaha av receiver, both with blown channels, when I looked inside and saw the STK modules, I was disappointed. Two reputable companies using, in my opinion junk.
You gotta love the chineese for making counterfeit electronics. This is true of a lot of products including the tools we use today. Better to mimic these components and make it better than the original using discrete components.
Depending on the circuit, I've replaced STK IC's with LM series IC's. Of course, you have to do both channels and some modification, but alot easier then dealing with fake Chinese parts.
Excellent video, it's videos like this that grow channels. Keep it up!
Never seen one home made. I've opened many fake STKs but all had factory made PCB and components looking almost like the original
I'm glad my Yamaha AX900U amplifier has discrete amp components. A/B transistors easily replaced and available. My amp was made in 1987, and still strong.
Interesting. It's a tough thing to find valid parts for most anything electronic - I can start a ramble on smartphone parts, automotive parts, computer parts, just about anything is knocked off and of truly substandard quality. I been repairing electronics for 25+ years and have witnessed the decline personally on the demise of repairable goods, and the what I can swear is purposely made scrap/junk replacment parts that are of ill fit, and if they work its a miracle and the repaired item will suffer from degraded performance at best. NOS , or a parts unit is the way I go these days and usually its just acquiring units for parting out in most cases to get a vintage item working correctly once again.
Even a lot of output transistors are now fake Chinese counterfeits. So even a receiver or amp with a discrete output stage can be challenging to repair with original parts. And some designs have stability issues with substitute transistors. Into an 8 ohm resistive load on a test bench everything might look good, but drive the amp to clipping into a real world reactive load (speaker) and it may oscillate when it clips which, at best, might destroy tweeters and possibly cause the amp to fail again. Modern transistors tend to be higher speed and higher gain both of which can contribute to stability problems. A lot of people doing repair work don’t understand this. In order to get good specs, a wide bandwidth, fast rise time, etc, amps especially from the 80’s often use massive amounts of negative feedback and as small as possible compensation caps along with small output inductors. Putting substitute transistors into these designs skews the phase shift in the amplifier and, under some conditions, negative feedback can become positive feedback with often disastrous results.
I remember my first experience with counterfeit transistors. It was servicing a Kenwood super eleven. The devices were bogus, and as soon as an inductive load was on the unit and any current was pushed through the amp, there was a bright flash and a fire. The amp had oscillated out of existsnce
Well said!
hi
i stumbled across this video and this channel after buying a counterfeit and defective svi module for a technics/matsushita amplifier..i am also a vaccum tube tv hobbyist so i have already subscribed. cheers
yes Sir i also received a counterfeit STK465 for my Akai amplifier same as yours.
I ordered a counterfeit module a while back in an attempt to repair an old Technics amp. As soon as I went to adjust the bias on the channel the protection relay clicked on - module dead. The manufacturer sent me another one and this time I barely turned up the bias pot and it's been working well. Still junk though.
Thanks for the video. Great info.
Good to know this. Thanks for sharing.
The fundamental idea behind STK is fine but units using these things certainly present a service challenge. I've also been caught out with fakes. Good luck finding one.
Could you please share with us what the fundamental idea of the STK series would be? I'm not entirely sure since I've some units appearing in hifi equipment made by reputable brands (Pioneer for example) ,and yet people in the diy audio community find it to be not so great in terms of audio quality and remark their fragility and tendency to fail.
I used to have a Realistic STA-130 that killed the RH speaker due to short in the STK chip, split supply amps using module chip are an accident waiting to happen, I prefer discrete transistor amps when it come to split supply format, The Dynavox CS-PA1 has a TDA chip but it's single ended capacitor coupling, I recently bought the MT-50 model and found it is split supply, also loud hum regardless of vol knob setting (3x louder than the mild hum from the CS-PA1)
The Chinese counterfeit almost everything. I only buy from good sources like Digi-Key or Mouser. Of course, that doesn't help for older parts.
interesting point! Even a lot of transistors are fake (if you go for original). When buying amplifiers to repair I avoid module-based precisely because of that
We all need good luck as Sanyo and Fisher were squashed several years ago by Panasonic.
Good job my freind
Yeah, I got burned by an ebay "reputable" distributor in Florida that when I complained the the part they sent me wasn't any good said. "We only said it was an official manufactured item (something like that). We didn't say it was the same as vintage items with the same number. "
This might be the same place. Did it start with an L or a D?
Hello Jordan, would it be possible to install a pair of STK056A (which are from Sony 24x2 amp) on a Sony amp 22x2 (stk056)? Thank you.
Interesting video you show there...I recently repaired a Sanyo DCA611. It uses 2 STK0059 IC's. Luckily one was burned and I ordered one from Germany. Certainly the weight point you mention there is true. They weigh less, but the plastic case does not go thicker or above the aluminium heatsink. I just don't know what to expect. The IC bought from Germany worked and still works but judging from your video, don't know for how long ? May be I can use the stk0050 replacement using real transistors and board with aluminum as demonstrated on some video here. Thank you
Sanyon semiconductor original maker of STK have been closed long time ago. If you want the original find used one. All new STK in the markets are for replacement and not original
I got conned by a distributor on E-bay. So I know what you mean. I have a Sony surround amp that has something similar as a center channel preamp. Got hosed on a claimed "pulled part" same with the amp transistors that were supposes to be complimentary darlington pairs.
Yes i agree with you about those stk chips I've been replacing a number of them, and it's becoming difficult to get original ones and the copys are bad + low quality.
I actually though it was interesting that someone could build the chip. But yes, you’re right in regards to honesty and reliability…..the chip doesn’t come close to the real chip and it probably should have been advertised that way.
Counterfeit market is a big problem in these days.
Cheers.
I have some experience with this too. I bought a replacement Darlington STK-0039 "Power Pack" on eBay that was supposed to be original. I could tell it wasn't original because the imprints on the chip were different, the 10 pins were not numbered. I installed one into my Pioneer SX-680 which had a bad channel. It was no easy task- I am not as electronically inclined as you- thermal compound has to be applied. The stereo worked for about 2 hours, then the power pack blew and it was dead again. I was pissed.
Sounds like you have some fault in your pcb lines. Even you buy pure Chinese copy of stk icS, it will still able to handle the same voltage and load. Load is important. Almost all stk series icS are rated for 8ohm load buy they run just fine with 6ohm load. If you use 4ohm load speakers on stk's icS it will blow up in loud and and long run. Lot of people doesn't understand about speakers impedance. Some are parallel 2 speakers in one channel which changes speakers impedance in half. Some time speakers coil gets short and those speakers will make sounds but they are the silent ic killer. First thing you can do is check your speakers impedance with a digital multi miter.
Me too ..same thing..sx680
I also had issues with them too on the same model Pioneer. It would make all these weird high pitch sounds.
Jordan, be very careful on eBay these days. Since the pan-----, they have closed down there telephone customer service, which had been outstanding. We're forced to send email back and forth to the Seller. Unscrupulous sellers know this and uses the time to run out the calendar until you either give up or the allotted time has expired. Very unhappy with eBay because of this.. I have been an eBay customer since 1999. No major purchases on eBay for the foreseeable future because of this.
Good luck finding an original replacement, I managed to find one a while back from China, clearly it was a used chip, but actually worked fine!
I really dislike these modules, apart from amplifier chips, they came as power regulators & convergence chips on projection TV's.
Hi JP. Thanks for uploading these great vids. I've really leanrt alot.I've this denon old AVC A1 amp 240v model which was working faithfully for years. Recently I connected a different set of 4 ohm towers (amp rated at 8 ohms)and it played well.But from time to time, it wouldn't turn on. The display appears to turn on then blinks and shuts down.Sometimes it works great without any issue.Do u know what could be causing this?
Not without seeing it. Could be power supply issue,. Amp going into protect mode from an intermittent fault, cold solder joint, or bad ground. Could also be intermittent amplifier fault
Jordan Pier
Thanks for the reply.I suspect the 4 ohm towers may have caused the output trans or driver trans to be damaged. B'cos I hooked up a different denon amp which worked for a while and then shut down too.Both amps are rated at 8ohms.Do u think I could replace just the output and driver trans on the amplifiers to handle 4ohm loads?
I wouldn't go replacing parts. If your speakers are pissing off two receivers, you've got bigger issues. 4 ohm speakers won't do well on an 8 ohms rated receiver, but will only shut it off at high volumes. No easy way to just replace parts to make it work.
You need more.output transistors, bigger capacity drivers and bigger rectifier , sometimes even a bigger transformer
Jordan Pier
Thought you'd say. Guessed as much.Only if it was that easy.Thanks anyways.
Uggghh, I always hated those amp on a chip designs---it's the ultimate in cheap, throw-away technology. I remember those being used in cheap shelf stereos from the 70's/80's, and they went bad often
So, question. If it had been assembled well (proper heat transfer, perhaps not potted) and identified properly as some sort of non-original retrofit device... how would you feel about that? Conceivably you would have no moral issue with it, but would you use such a device?
If it worked properly and reliably, I'd have no problem using it
Do u know if the counterfeits are noticably lighter in weight?..im trying to figure a way to tell if real or fake without takjng apart?.. my real stk 4191 weighs 45g...the real one u had looks lot like mine...fyi the originals are almost impossible to take apart..unless you do a cut out...could you weigh your fake one vs your real one and let me know the weight in grams? if possible.
The fakes are noticeably lighter.
@@JordanPier thanks a lot im trying to find an original so im asking ebay sellers to weigh theirs..one guy came back and said 45g which is about what my orig is....i dont want a fake....i want high quality orig..my orig lasted 40yrs i dont want a chinese fake that will last 1 week lol
J.P .D THE BEST on You Tube !!!!!!
I have original sanyo stk from olds compo stk 4132ii and 4192ii
Interesting, I’ve never opened the hood of an stk device
Whats the best way to test these? Can I test in circuit? How do you tell the fakes?
Fakes usually have notch (crossover) distortion, or do t pass power output tests without blowing up
@@JordanPier I need one of those Mr Carlson Lab testers. lol. I bet they are all fakes but I was hoping they were pretty good ones. I wonder if there is a way to cut open and repair an original? I have a dead SVI here.
If u r able to can u tell me the weight in grams of the knockoff stk
They vary. I don't have one on hand right now to compare.
@@JordanPier ok well when you say considerably lighter can you give me a % is it 10% lighter 20% 30% 40% 50%.....is it substantial or just a bit is what im asking..im trying to buy a genuine and need to have idea what the fake will weigh..do u have a genuine u can weigh..?
Hope you get your money back, I would name and shame the supplier so everyone knows, the supplier must know he's selling these crappy things.
Had the same problem with order from Ali express, seems to have huge cross overdistortion, all of them.
Stk 4141.......
Plesse tell me about this ic.
pdf1.alldatasheet.com/datasheet-pdf/view/41598/SANYO/STK4141.html
@@JordanPier is the ic available in your country......????
I had crossover distortion with a fake one...
I wonder whether there's a detriment in ditching them for TDA2050 or something like that. Because hunting those shits down won't be sustainable.
I had a Yamaha r-300 with a cooked ig type device(yamaha's stk) and swapped in some tda-7293 in it's place. Extra effort, but sounded fine. That might be the future for these sets unless someone starts making good ones
I've had no problem in getting my money back for dodgy goods on ebay.
I have a marantz reciever and a yamaha av receiver, both with blown channels, when I looked inside and saw the STK modules, I was disappointed. Two reputable companies using, in my opinion junk.
Either eBay or pay pal will get your money.,and because it a fake they don't want you to send it back so they can resell it .
So wait you mean the built-in protection might not work?! (joking)
Yup there all counterfeit.think about it,they are all discontinued parts.anytime u see discontinued parts being new,they are all fake.no surprise.🙂
Name and shame the seller