The HUMMMMMM is DUNNNNNN !!! lol . I'm sick as Foooooke? The way your so at ease with testing & fault finding? I can only dream. I need a mentor, with skills like yours. You know we all praise your skills? And how we're all facinated by your troubleshooting technique & skills?

Good idea, with a nice result!

I loved this mod! & leave it up to Steve to adapt & overcome. Great job my friend!

So you effectively replaced junk with better junk. Nice mod! Myself, I just replaced 20+ caps in an older Sony 5.1 AVR and got it working again at full volume on all channels! Love the Nichicon caps!

Great fix! Merry Christmas.

Merry Christmas to you and your family. Thanks for all the vids this last year. 🙌

@norcal715

2 жыл бұрын

Thank you Barry! Merry Christmas to you and your family in Louisiana!

Very cool project! Ingenuity at its best

Great video and nice solution, regards

Merry Cristmas NorCal :)

Great way to save it nice work .

Nice merry Christmas 🎄

You are a very smart man

Merry Christmas to you

Nice frankenstein-repair :D

Nice fix.

Merry christmas

I have to say you made it better than what sony made it. in fact you can say made in the USA.

Probably underspecced transistors, likely only rated for 40VDC rails only, and thus cooked on 60V. After all, getting a 80V transistor might cost an extra cent each.....

😢 wow I wish that was my amp being fixed

Nice MOD.!

Great work! Just a question, don't you need some frequency filtering? You replaced the Sony am with a "regular" amp, right? So I thought all frequencies (20Hz-20kHz) are being amplified right now. But I think you drive it with your already low filtered output of your receiver's pre-amp.

@norcal715

2 жыл бұрын

The low pass is built in to the preamp circuit.

The STK404-140N-E made by ONsemi was a great replacement but its obsolete and only Rochester Electronics sells them and you have to buy at least 38

Now it's more stable than the Chinese STK chip.

We all love to blame the Chinese STK amplifiers as we are all aware that there was some fakes getting around some time ago... But from what I saw in the one that you opened, it has been designed properly and shouldn't have failed! The fact that the little driver transistor had failed along with the output transistor, I'm thinking that the actual reason why it failed was due to something else before it.. either a resistor has gone out of tolerance or you have a very leaky capacitor which would explain the hum! I would have checked for esr but most importantly I would have checked for V loss which is what the Chinese use for leakage current of capacitors... That STK should not have died that quick unless something else in the circuit before it made sure it did..

@norcal715

2 жыл бұрын

Since the original was doing intermittent crackling at moderate volumes only after warmed up, and the 1st replacement cured it for about 1 month, I do not think it was a capacitor or resistor issue. It's a pretty basic circuit. The 2nd one didn't last 10 seconds. Just cheap Chinese crap is all that is available.

@PeterMilanovski

2 жыл бұрын

@@norcal715 the reason behind my original post was simply because of the bad stigma that the Chinese made STK's have acquired from early productions.. while there might still be some fakes floating around out there, there's plenty that are as good as the originals. I have built amplifiers based on the Chinese STK amplifiers and they are actually pretty good... So to see you install one and only last a short time, and the inside looked like it was well built and designed... Tells me that something else caused it to die. I would have went looking for what the actual reason was for it to fail... Just to know! Yeah it's just easier to say cheap Chinese junk.. even though you probably own plenty things that were made in China and are not junk..

@marka1986

2 жыл бұрын

The cheap failing stk packs are a real problem. Went through 3 for a customer. Had to tell him not to use more than 1 set of speakers at a time. So far been a year. It's stk0050. Xraytonyb has a video about getting a board with discrete transistors to replace that pack. The cost and time probably would be excessive in most cases.

@PhuckHue2

2 жыл бұрын

@@PeterMilanovski Those Chinese ones are junk and don't last. I just replaced another one recently. The only one that worked was the STK404-140N-E made by ON Semi

@PeterMilanovski

2 жыл бұрын

@@PhuckHue2 I have used them in my own equipment and haven't had any issues, but I always check all the capacitors for DC leakage if an STK has failed, it's the only component that can cause a failure apart from blown speakers or X-Overs....

So....I agree with both sides of this debate. I have had both situations. My experience has been replacement of STK modules from China have worked great, as good or better than original outputs, but some have been “cheap”, and failures vs originals circuits. My thoughts...but...just my thoughts....and everyone start typing to crush me. The older the design, the better the STK’s from anywhere will work. The newer units with tighter thresholds of tolerance electronically and output....the more prone to failure. The higher the output, the more trouble you will see. Its an engineering issue for me. You want stable output...buy an old Marrantz or Pioneer unit, with real outputs per channel. If that goes bad, real diagnosis and repair can happen easily. Much like all old equipment, even in the early module days.

@PhuckHue2

2 жыл бұрын

I've had some that worked but they don't last. Every few years they crap out and have to be replaced

Are you sure the stk chip was bad or maybe shorting those 2 pins together might have caused the problem

@norcal715

2 жыл бұрын

I don't think so, the other one failed without the pins shorted, in short order.

Jorden Pier replaced a bad STK ... with a couple of amp modules.... but I think the modules came from Banggood so he just installed more Chinese junk....

I have same problem with my SONY sub- looking for STK404-140S

@norcal715

Жыл бұрын

I have not found any good replacement STK404-140S in over a year (as of July 2022)

There are cheap Chinese parts and there are quality Chinese part. What u pay is what you get. Cheap people always buy the cheapest part and when they break down, the cheapos always complain.

@norcal715

2 жыл бұрын

When that is all that is available that is what you have to use!

@leonwangls

2 жыл бұрын

@@norcal715 You flatter china manufacturer by saying no one else can produce what you want. What do u need that has to be of such high quality and china is the only producer

All the JFETS that came in the mail from ebay today test as BJT's. Got me again china, shame on me

@norcal715

2 жыл бұрын

I have had that happen, I just ordered some 3AG fuses (6mm x 30mm) and reveived the correct value, the problem is they were 5mm x 20mm. I have a saying I adhere to "If you lower your expectations far enough, you will never be disappointed".

i see STK , i walk away .

The stk you got is cheap knockoff of the original one I know this because the color of the writing on the back and from some of the markings on the body of the stk itself

@norcal715

2 жыл бұрын

You are correct. I think if I could have found an original Japanese ic it would have been ok for many more years.

I find these type of POWER AMPS to be utterly useless cause you dont know what crap the chineese has put in these devices. Funny years ago we use to complain japan produced crap. Sad to say Japan does not make good components anymore.

No doubt you're aware that applying heatsink compound with bare fingers, is not good form, even if you get away with it.

@norcal715

2 жыл бұрын

Ya, I have only been doing it for about 40 years that way.