Seeing thousands sold and good feedback I broke one of my own rules and bought "AD797" on Ebay...
Literally thousands have sold (see attached first photo) including over 2,500 in just the five packs.
After extensively searching the feedback containing "AD797" I gave it a try. One feedback even reads "confirmed AD797 device type". What did I get? The branding looks like AD797...
Well the AD797 quiescent current is 8.2mA. I measured 1mA like an LM741... The AD797 input offset voltage spec is 80uV max. I measured 0.3V, 0.8V and 0.9V like LM741...
What about pin 8 which is the distortion cancellation and compensation pin on the AD797? On the ones I received pin 8 is no connect. No diode junction of any kind and completely open circuit. Real AD797 has a connection on pin 8. LM741 is no connect on pin 8.
I probed the offset null circuitry from Pin 1 to 4 and Pin 4 to 5 and it looks like... ...an LM741 with 1kOhm resistors. (See attached images which include an LM741 schematic.)
Since thousands have been sold and given five star reviews... ...I wonder... ...did any other DIYAUDIO forum members buy any? If you did can you please probe yours and post the measurements for simple fake detection? (Such as quiescent current, offset voltage, offset null circuit resistor values. Is pin 8 open circuit?) Do you unknowingly have LM741 in your pre-amp or DAC I/V stage?
Am I the only one who seems to have received LM741 that are marked AD797? (I doubt it.) Did thousands of people really get LM741 marked like AD797 and then leave five star reviews?!? I bought from "Adeleparts2010".
Literally thousands have sold (see attached first photo) including over 2,500 in just the five packs.
After extensively searching the feedback containing "AD797" I gave it a try. One feedback even reads "confirmed AD797 device type". What did I get? The branding looks like AD797...
Well the AD797 quiescent current is 8.2mA. I measured 1mA like an LM741... The AD797 input offset voltage spec is 80uV max. I measured 0.3V, 0.8V and 0.9V like LM741...
What about pin 8 which is the distortion cancellation and compensation pin on the AD797? On the ones I received pin 8 is no connect. No diode junction of any kind and completely open circuit. Real AD797 has a connection on pin 8. LM741 is no connect on pin 8.
I probed the offset null circuitry from Pin 1 to 4 and Pin 4 to 5 and it looks like... ...an LM741 with 1kOhm resistors. (See attached images which include an LM741 schematic.)
Since thousands have been sold and given five star reviews... ...I wonder... ...did any other DIYAUDIO forum members buy any? If you did can you please probe yours and post the measurements for simple fake detection? (Such as quiescent current, offset voltage, offset null circuit resistor values. Is pin 8 open circuit?) Do you unknowingly have LM741 in your pre-amp or DAC I/V stage?
Am I the only one who seems to have received LM741 that are marked AD797? (I doubt it.) Did thousands of people really get LM741 marked like AD797 and then leave five star reviews?!? I bought from "Adeleparts2010".
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The "5 star revues " will be fake this is a major issue just now with genuine online companies and operators I get updates from them .
Several businesses of long standing with ( in one case ) 50 years of good service which had a 5 star rating all of a sudden had nearly 100 1 star ratings which on check up turned out to be bogus addresses - bogus names - non existent personal details etc .
In other words the scammers are getting hackers to send out those posts to get customers to buy from them .
Every day my old website sends me emails with posts about NY share scammers offering large sums for their shares , either their NY office doesn't exist or its not as advertised - please sign this non-disclosure--and we will need £xxx + to convey this transaction.
Sadly some people fall for it.
I am genuinely sorry that you were "taken " by this scam .
Thank you for posting the eBay name it will help others , I notice its all from China , I said here and on my previous website that China will "build to a price " , when I last checked there are many 100,s of "Chinese chip makers " but while the big names are okay the scammers know which ones will "do their bidding " .
Also they pay "buttons " for large supplies of the dud goods I spent a long time in the past checking them out .
Is eBay now like Amazon "Marketplace " where I read the latest rules small print where ( due to developing a bad reputation ) Amazon has legally removed their legal obligations which only apply now to Amazon itself --NOT the "Marketplace " ?
Several businesses of long standing with ( in one case ) 50 years of good service which had a 5 star rating all of a sudden had nearly 100 1 star ratings which on check up turned out to be bogus addresses - bogus names - non existent personal details etc .
In other words the scammers are getting hackers to send out those posts to get customers to buy from them .
Every day my old website sends me emails with posts about NY share scammers offering large sums for their shares , either their NY office doesn't exist or its not as advertised - please sign this non-disclosure--and we will need £xxx + to convey this transaction.
Sadly some people fall for it.
I am genuinely sorry that you were "taken " by this scam .
Thank you for posting the eBay name it will help others , I notice its all from China , I said here and on my previous website that China will "build to a price " , when I last checked there are many 100,s of "Chinese chip makers " but while the big names are okay the scammers know which ones will "do their bidding " .
Also they pay "buttons " for large supplies of the dud goods I spent a long time in the past checking them out .
Is eBay now like Amazon "Marketplace " where I read the latest rules small print where ( due to developing a bad reputation ) Amazon has legally removed their legal obligations which only apply now to Amazon itself --NOT the "Marketplace " ?
I did and today they partially refunded (I am out the shipping).
I attached their reply. They are still selling them and I doubt I will ever hear back about them "contacting their supplier". And they want me to change the negative feedback, however I don't want others to get cheated.
We apologized for the inconvenience caused.
You know, we just a trader and my supplier told me that this part are BRAND NEW AND ORIGINAL.
We will contact with them shortly to see what happened and will update you later.
At the moment, we'd like to refund your full money and May I ask you to change the negative feedback to positive feedback?
Thanks for your understanding and supporting.!
Have a nice day!
Regards,
Yours sincerely,
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Yeah, this counterfeit crap really hits a nerve with me. It causes doubt and suspicion in the marketplace. I built a couple of chipamps from Aliexpress, and they promptly blew up on powerup! Ditto for TDA7293. I then ordered LM3886's from Digikey, and no problems. I see amp kits on ebay or aliexpress that include "original" Toshiba 2sk170's. Yeah right. Guess the moral is...don't buy that crap, and maybe one day they'll smarten up.
And even if you do report the vendor to Ebay ( it contravenes the selling policy) NOTHING happens.
I reported the transistors ( My Transistors, original or copy? ) and they are still listed.
Andy
.
I reported the transistors ( My Transistors, original or copy? ) and they are still listed.
Andy
.
Don't worry about giving a vendor bad feedback. If it gets TOO bad, they can drop that trading name and re-open under another name. That has happened to me (on Amazon) twice this winter. Amazon Seller - FluxLab turns out to be Dealco which has been slipping below 66% 5-star marks.
My order was not THAT screwed-up, but it is clear from a year's history on both storefront names that this vendor has/had an extremely high screw-up percent. Now the record of my purchase is gone so I *can't* change my feedback. Oh well.
I did also report the messages to Amazon.
Another vendor turned out to sell under three different names and is not really in the quiet Pennsylvania town they claimed.
My order was not THAT screwed-up, but it is clear from a year's history on both storefront names that this vendor has/had an extremely high screw-up percent. Now the record of my purchase is gone so I *can't* change my feedback. Oh well.
I did also report the messages to Amazon.
Another vendor turned out to sell under three different names and is not really in the quiet Pennsylvania town they claimed.
There wouldn't be any wonder if those 741 in desguise ended on 2500 audiopile DAC boards on same ebay. fake pcm1794 + fake ad797...just imagine what an audiopile sound would that make!Do you unknowingly have LM741 in your pre-amp or DAC I/V stage?
I'd advise sticking to recycled parts if you want a fair chance of 'cheap' not being fake. Which generally means SMD packages as recycled DIL is jolly hard to find.
Checking Taobao, the sellers with credible offerings are priced around $9 each for AD797 and look like this :
Checking Taobao, the sellers with credible offerings are priced around $9 each for AD797 and look like this :
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What is sometimes not understood (by those outside the industry) is that manufacturers with volume purchase agreements routinely pay a tenth of the prices listed on Digikey and Mouser. That is the reason for the puzzle of assembled products containing actual genuine chips that cost less (including shipping) that you can buy just the main chip for. At Digikey or Mouser prices you could not possibly buy the assembled raw components for anything (TV, amplifier, computer, whatever) for anywhere near the price of the assembled, tested and packaged product you buy in the store.
Also I am sure that the LM741 type being used in the fakes is coming from the least expensive fabs in the least expensive regions of the world.
Also I am sure that the LM741 type being used in the fakes is coming from the least expensive fabs in the least expensive regions of the world.