STK2145 Enigma - fake?

[PE9ZZ]

I'm trying to help out (remotely) a forum member on the Dutch forum Buizenradioclub (tube radio club). His Akai AM-U33 blew its STK module. After getting a replacement module from Littlediode it went into almost full conduction leaving only a few volts due to the fortunate use of a DBT. When taken off the board a sanity check for the bias section (take a 5 V supply and 560R resistor and hook this up to pins 16 and 10/1 and 7) I would have expected some 2.5 V on these pins. Not so. There was no current draw whatsoever. From another supplier (apparently via-via Europarts) another module was procured with the same results for the sanity check. I'm flabbergasted. I have no idea what is going on. Did this guy manage to buy two fake/dud STKs or am I overlooking something? Actually, the original blown module does have resistance between these pins (about 2k).

Incidentally, the driver module was tested as well and found OK. Without the output module but with biasing diodes it successfully got a functional feedback loop.

Drat. I hate these modules...

 

[clinic-audio]

 

[nj pheonix]

I have been told that the bulk of of the NOS STKs was bought up by seller wehavethatitem (by a very reliable source). No idea if he has that piece ( no affiliation).

 

[PE9ZZ]

You want PICS!!!!! Here are PICS!!!!!

These are the module's internals:


This is the driver module test:


This is the bias circuit test:


Bias circuit resistors:


Meter showing 5.1 instead of 2.5 V:


STK under test:


Note the faded print. Every self respecting clone has white print.

This enough pictures for you, Mr. Clinic?

 

[Skywatcher]

I have been told that the bulk of of the NOS STKs was bought up by seller wehavethatitem (by a very reliable source). No idea if he has that piece ( no affiliation).

Someone else took over the business and I received some FAKE parts from them.Orrin and Adele are no longer there. What they sent me was very obviously remarked AND the guy "Jay" claimed the listing never mentioned "Sanyo" pretty much admitting they were fakes. They are no longer on my list of "trusted" sellers.

 

[PE9ZZ]

For me the most important question is why make a fake that fails the sanity check? The bias circuit is simply not connected. I'd rather buy from Jack Ma (Aliexpress) because if I get a bad part I get my money back. I had that twice and was reimbursed twice. So my forum member should have shopped in China.

I'd love to have a peek inside these dud modules. Maybe I can lay my paws on them and compare to the borked original. Usually the thick film resistors go phut. Had I said I hate these modules? Now especially with these (alleged) fakes.

Edit: turns out the first STK did not come from Littlediode but from Aliexpress. I stand corrected here...

 

[quaddriver]

Someone else took over the business and I received some FAKE parts from them.Orrin and Adele are no longer there. What they sent me was very obviously remarked AND the guy "Jay" claimed the listing never mentioned "Sanyo" pretty much admitting they were fakes. They are no longer on my list of "trusted" sellers.

that is good info. in the past I have obtained 'nos' parts from them and they seemed to be nos, looked nos and worked nos. I know vince at galaxie was getting 'NTE' stuff as listed in his mr repairman books from ??? I dunno...

 

[Tom B]

Someone else took over the business and I received some FAKE parts from them.Orrin and Adele are no longer there. What they sent me was very obviously remarked AND the guy "Jay" claimed the listing never mentioned "Sanyo" pretty much admitting they were fakes. They are no longer on my list of "trusted" sellers.

Here is a bit of history. Attached is the inventory I did in Florida of all those parts that my friend had as he was shutting that part of his business. I took maybe 5 of most STK's, Sanken SI's, and STR's he had plus an assortment of Sanken S-80's, and centain transistors, diodes, and IC's I thought I may use in the future. As they closed, I was told all of these "Boxes" of NOS parts were put on a palel or 2, bikini wrapped and sent to Orrin in NJ. If the part you are looking for is on this list, and the list shows sufficient qty, then "wehavethatitem" may still have original NOS parts. If what you are looking for is not on this list, I wouldn't know where he got them from. I can tell you that common STK's like the 0040, 0050, 0060, 0080, and 0100 were long gone and not in this load. But if you need 10,000 of the 2sc1060's TO220 transistor or 30,000 2sc2665's transistor, wehavethatitem may have some.

 

[Tom B]

I have never been happy with products from aliexpress or UTSource. It seems some of their parts are just restamped, and the internal circuitry is nowhere close to what it should be. 2 times I tried getting Yamaha single channel driver chips, and was sent something that looked similar to what I expected. But showed as a short on dim bulb. simple resistance checks showed it probably was a 2 channel driver chip that was a lot more common (left side measurements were a mirror of the right side) 2 channel voltage amplifier like the STK3082

 

[Skywatcher]

that is good info. in the past I have obtained 'nos' parts from them and they seemed to be nos, looked nos and worked nos. I know vince at galaxie was getting 'NTE' stuff as listed in his mr repairman books from ??? I dunno...

Up until Adele finally left and sold out, I got nothing but Genuine components. Orrin passed away last year and Adele tried to keep it going. She relocated the business to a new address, reopened, then a few months later she gave it up. I don't blame her, her and Orrin had the business for decades.

 

[Skywatcher]

Here is a bit of history. Attached is the inventory I did in Florida of all those parts that my friend had as he was shutting that part of his business. I took maybe 5 of most STK's, Sanken SI's, and STR's he had plus an assortment of Sanken S-80's, and centain transistors, diodes, and IC's I thought I may use in the future. As they closed, I was told all of these "Boxes" of NOS parts were put on a palel or 2, bikini wrapped and sent to Orrin in NJ. If the part you are looking for is on this list, and the list shows sufficient qty, then "wehavethatitem" may still have original NOS parts. If what you are looking for is not on this list, I wouldn't know where he got them from. I can tell you that common STK's like the 0040, 0050, 0060, 0080, and 0100 were long gone and not in this load. But if you need 10,000 of the 2sc1060's TO220 transistor or 30,000 2sc2665's transistor, wehavethatitem may have some.

Well, I can say for a fact that their current stock of STK0080II are counterfeit and clearly show being remarked.

 

[Skywatcher]

I have never been happy with products from aliexpress or UTSource. It seems some of their parts are just restamped, and the internal circuitry is nowhere close to what it should be. 2 times I tried getting Yamaha single channel driver chips, and was sent something that looked similar to what I expected. But showed as a short on dim bulb. simple resistance checks showed it probably was a 2 channel driver chip that was a lot more common (left side measurements were a mirror of the right side) 2 channel voltage amplifier like the STK3082

I did get lucky with UTSource with a pair of Yamaha/STK driver modules. They were clearly used, which I didn't care as long as they worked. They worked just dandy and as far as I know, 18 months later still working. I did put heat sinks on them and that may be why they still work. But I have heard horror stories from others getting "bum" parts, as well as a number of "success" stories. It's a coin toss with them.

 

[Tom B]

These are the ones I got from UTsource on 2 different occasions. There are actually a number of ebay companies that fly under the utsource umbrella.
These were all bogus


Notice the printing is a bit crooked, which is always a bad sign.

 

[clinic-audio]

You want PICS!!!!! Here are PICS!!!!!

These are the module's internals:
View attachment 1969681

This is the driver module test:
View attachment 1969682

This is the bias circuit test:
View attachment 1969683

Bias circuit resistors:
View attachment 1969684

Meter showing 5.1 instead of 2.5 V:
View attachment 1969685

STK under test:
View attachment 1969686

Note the faded print. Every self respecting clone has white print.

This enough pictures for you, Mr. Clinic?

Yes , much easier to see what you are working on
I have to double check with my stock if there is any original STK2145

 

[PE9ZZ]

These are the offending modules. The one from Aliexpress:


The one from Europarts:


The original, borked module:


A bit crap resolution but it will do for the illustration. Still, I have no idea why these two units fail. I don't have them in hand so I cannot test/open them.

 

[PE9ZZ]

There is some progress. One module was opened and these are the internals:


It is clear that pins 8 and 9 are connected which means that it is not an STK2145 clone. Also, there are no emitter degeneration resistors. I tried to reverse engineer the board but failed because some parts are missing in the pic.

 

[Skywatcher]

There is some progress. One module was opened and these are the internals:
View attachment 1970540

It is clear that pins 8 and 9 are connected which means that it is not an STK2145 clone. Also, there are no emitter degeneration resistors. I tried to reverse engineer the board but failed because some parts are missing in the pic.

Definitely NOT a Sanyo. Just the soldering "job" alone tells the story, not to mention the SMT components. It's such a waste, but good for "profits". Jeeeezzze, if they would actually use the correct type of components, they would be a good thing instead of garbage.

 

[PE9ZZ]

But that is not news. This is a clone, not an original. The thing is that it's not a clone for an STK2145. I may be getting this thing and when I do I will reverse it thoroughly. And that blob of solder on the right transistor in the middle definitely should not be there...

 

[gadget73]

I had something act like this once. The STK was bad in that case, one channel gave me half a sine, the other was basically at rail voltage. I replaced the module with a known genuine NOS piece. That fixed the half-dead channel but the rail voltage remained. Turns out it was a shorted small signal transistor upstream of the STK. It was dumping full voltage to the input, and the STK responded by attempting to amplify it. Only real clue was that the voltage at the output was about 2v lower than actual rail voltage, which accounted for the voltage drop across the output transistors within the STK.

so my advice would be confirm exactly what the output voltage is vs rail, and see what the input looks like. Possible you're looking in the wrong place here.

 

[Skywatcher]

These are the ones I got from UTsource on 2 different occasions. There are actually a number of ebay companies that fly under the utsource umbrella.
These were all bogus
View attachment 1970090

Notice the printing is a bit crooked, which is always a bad sign.

Crooked printing does occur on "legit" components, but these modules are clearly bogus.