To check that a TDA7293 integrated circuit is genuine and not a fake made from a re-printed TDA7294 you can perform the following simple tests:
Using any reasonable quality 3.5 digits DMM set for resistance measurement (or the highest resistance range if it is not auto-ranging):
Positive probe to the metal tab and the negative to either pin 5 or 10 or 11 should give a reading of around 3M Ohms in the genuine device. Reversing the polarity should not show any reading. If you do not get these readings then the device is a fake since in the TDA7294 all these pins are not used (N.C.). This is a reliable test and the results are conclusive.
Explanation: Pin 5, 10 and 11 in TDA7294 are not connected (not used) but in TDA7293 they are used for cascading (and detection indication pin-5). Only the TDA7293 is capable of cascading to give more output power using multiple ICs.
Obviously there are more tests you can perform with a DMM but it is not really necessary, however, I will list them all the same:
+ve probe to pin 1, -ve to pin 5 should read around 4.5 M Ohms reversing the polarity should show around 8 MOhms reading.
+ve probe to pin 11, -ve to pin 1 should read around 8.5 M Ohms
+ve probe to pin 15, -ve to pin 12 should read around 12 M Ohms
Visual inspection of the suspected device often provides indication of counterfeited devices. Genuine STM device markings are laser engraved while a fake is likely to be printed. STM like most manufacturers nowadays laser engrave the devices in order to combat the counterfeiters. The laser markings often use unique or very distinctive fonts.
The TDA7293 is an extremely popular device extensively used in power amplifiers (Audio and non-audio) and in vast volumes by manufacturers ranging from the professional to the consumer products. This provided the fakers with the incentive to flood the market with fakes made from a re-printed cheaper device (and of lower performance) TDA7294.
There are plenty of genuine devices as well as fakes available over the internet (Ebay, Amazon, Ebid etc.). Buying in small or medium quantities is uneconomical from franchised distributors due to their operational and overhead costs. So here are a few simple rules to minimise the risk when buying on the internet:
1. Avoid sellers who do not show a CLEAR picture of the ACTUAL device. They have something to hide and do not be fooled by any commercial indicators such as trusted seller, to-rated seller, registered company, large feedback ratings, experienced seller, or a professional sounding name etc.
2. Do not buy devices that are printed.
3. Only buy devices that are laser engraved and carefully examine the provided picture.
4. You must reject the devices if they differ from the listed picture. This is your right by law and the selling medium (Ebay, Amazon, Ebid, Paypal etc) should support you 100%.
5. High price is not an indicator of authenticity. Quite often counterfeiters use a high-price to hoodwink buyers.
The thing to remember is that a fake TDA7293 device made of re-printed TDA7294 will work in a circuit but with lower performance. Also a fake device will provide output power when used as the first device in a cascaded configuration but the rest of the cascade will always be idle. In an audio power amplifier you will only notice that when you try to get more output power.
Attached is a picture of the genuine device to help readers see the laser engraved IC markings.
Using any reasonable quality 3.5 digits DMM set for resistance measurement (or the highest resistance range if it is not auto-ranging):
Positive probe to the metal tab and the negative to either pin 5 or 10 or 11 should give a reading of around 3M Ohms in the genuine device. Reversing the polarity should not show any reading. If you do not get these readings then the device is a fake since in the TDA7294 all these pins are not used (N.C.). This is a reliable test and the results are conclusive.
Explanation: Pin 5, 10 and 11 in TDA7294 are not connected (not used) but in TDA7293 they are used for cascading (and detection indication pin-5). Only the TDA7293 is capable of cascading to give more output power using multiple ICs.
Obviously there are more tests you can perform with a DMM but it is not really necessary, however, I will list them all the same:
+ve probe to pin 1, -ve to pin 5 should read around 4.5 M Ohms reversing the polarity should show around 8 MOhms reading.
+ve probe to pin 11, -ve to pin 1 should read around 8.5 M Ohms
+ve probe to pin 15, -ve to pin 12 should read around 12 M Ohms
Visual inspection of the suspected device often provides indication of counterfeited devices. Genuine STM device markings are laser engraved while a fake is likely to be printed. STM like most manufacturers nowadays laser engrave the devices in order to combat the counterfeiters. The laser markings often use unique or very distinctive fonts.
The TDA7293 is an extremely popular device extensively used in power amplifiers (Audio and non-audio) and in vast volumes by manufacturers ranging from the professional to the consumer products. This provided the fakers with the incentive to flood the market with fakes made from a re-printed cheaper device (and of lower performance) TDA7294.
There are plenty of genuine devices as well as fakes available over the internet (Ebay, Amazon, Ebid etc.). Buying in small or medium quantities is uneconomical from franchised distributors due to their operational and overhead costs. So here are a few simple rules to minimise the risk when buying on the internet:
1. Avoid sellers who do not show a CLEAR picture of the ACTUAL device. They have something to hide and do not be fooled by any commercial indicators such as trusted seller, to-rated seller, registered company, large feedback ratings, experienced seller, or a professional sounding name etc.
2. Do not buy devices that are printed.
3. Only buy devices that are laser engraved and carefully examine the provided picture.
4. You must reject the devices if they differ from the listed picture. This is your right by law and the selling medium (Ebay, Amazon, Ebid, Paypal etc) should support you 100%.
5. High price is not an indicator of authenticity. Quite often counterfeiters use a high-price to hoodwink buyers.
The thing to remember is that a fake TDA7293 device made of re-printed TDA7294 will work in a circuit but with lower performance. Also a fake device will provide output power when used as the first device in a cascaded configuration but the rest of the cascade will always be idle. In an audio power amplifier you will only notice that when you try to get more output power.
Attached is a picture of the genuine device to help readers see the laser engraved IC markings.
Attachments
Yes I agree with you Nigel that parts from RS should be genuine, but I do not agree that they are cheap. For example; building a stereo amplifier using the widely available ready made PCBs (7-aside) requires 14 TDA7293V. These cost £72.72 (incl. free delivery) from RS. By contrast buying the same 14 from a very reputable supplier on Ebay would cost £16 with free delivery. So RS parts are over 350% more expensive. Also there is no guarantee that RS have them in stock (I checked that an hour ago) and you end up on back-order waiting list. Best regards
+1
Here in our part of the woods RS has the widest selection - but the audio stuff are forever on back-order - so frustrating at times.
Are there any fake TDA7297's around? I recently bought 2 x TDA7297 diy amp boards with all the components for $1 from AliExpress. They sound marvelous for the price and size. Compared to the RS price for one TDA chip, I still cannot believe the economy of scale and one starts to wonder about fake chips.
But you will be 350% more likely to get duff ones, still at that price buy extras just in case.
I prefer peace of mind. Farnell are sometimes less expensive.
Just want to say a big THANK YOU to ICforensics as I manage to spot fake TDA7293 according to his prescription. I have performed all measurements as stated above, none is in accordance with the given reference measurements. I would particularly point out that fake devices look the same and feels as the original image...I guess I got a first-rate counterfeit.
PayPal claim for full refund opened...
A link to fake TDA7293 (2nd and 3rd image) TDA7293 STMicroelectronics,ZIP-15 | IC Chips | UTSOURCE
PayPal claim for full refund opened...
A link to fake TDA7293 (2nd and 3rd image) TDA7293 STMicroelectronics,ZIP-15 | IC Chips | UTSOURCE
As a pro audio shop owner, I never buy parts on ebay. You might get some great prices, and you might often get good parts, but all it takes is one bum order, and it blows away all the "savings" we got the rest of the year from ebay.
If a customer complains about what I charge for parts, he is welcome to bring his own, and I will install them. And I will then also not warrant the work.
If a customer complains about what I charge for parts, he is welcome to bring his own, and I will install them. And I will then also not warrant the work.
UTSOURCE !!!!!
That says it all.
They have been previously noted for supplying fakes although they also sell genuine stuff as well.
Andy
..
I'm fully aware of fakes from utsource (like 10 years or so), but they do sell genuine devices as well. So you have to develop strategy...as I have. Like buying large quantity real McCoys for pennies and couple of various interesting (rare) devices in one deal (read shipping) for testing, be it with curve tracer, in-situ, whatever...
1) The "tab" is *often* connected to the *most negative* part of the chip. (This is from how the NPN layers are stacked in chip-making.)
1a) This also means you usually can not bolt a power chip to the chassis or chassis-mount heatsink without some insulator.
2) The datasheet clearly shows that "Tab connected to pin 8".
3) "rings"? You mean the Continuity tester? That is for trailer-light mechanics. It does not know a short from a deliberately low resistance. Electronics people go by the *numbers*, not an arbitrary yes/no beep.
Attachments
Yes, I agree. The 7294 seems to have decent specs and costs only a little more.
Just for the fun of it I'm going to buy a 7293 and 7294 from Digikey, and compare both of them to some $2.89 7293's from Ebay . From what I understand people seem to get good performance from the cheaper Ebay chips. But what exactly are they?
Just for the fun of it I'm going to buy a 7293 and 7294 from Digikey, and compare both of them to some $2.89 7293's from Ebay . From what I understand people seem to get good performance from the cheaper Ebay chips. But what exactly are they?
I find Farnell are much better for low volumes.
With RS I have to buy 5 or 10 min but Farnell often sell one off's.
My view is if it says "Chinese", "Cheap" or "ebay" then you are looking in the wrong place ! Ok, some Chinese stuff is ok (like pcb's where I have had good results) but its a bit of a lottery otherwise. If you never turn a Chinese amp up to full volume you will never know if it is going to break !
I have to disagree with the comment someone said about RS being expensive. With some exceptions they are great value for money.
After all "Buy cheap, buy twice" ! then probably end up back at RS.
And if you are selling stuff on what does a full return cost if there is a problem?
I bought some irfp240's off ebay for an amp. The amp turned on great and played music great. I then unplugged my soldering iron and the amp blew up. So it was clearly a spike getting down the mains and into the amp which blew the transistor up probably pushing it into breakdown.
I wasn't sure if to improve power supply or not but I thought first I will buy some genuine transistors from RS. I fitted them and despite trying extremely hard glitching the mains I couldn't get them to blow up. Still going 3 months on.
That's a good warning , and I agree that you're not saving that much money that it's worth losing the piece of mind when investing lots of time into a project that is otherwise solid.
Hi to everyone
i've got two tda7293, pulled out of a power amplifier.
with the tda's in circuit the amp power light blinks and doesnt work nothing, but powering up the amp without the tda's(desoldered), it stay on and the power supply section works and the pre amp section too.
my question is:
is any way with a multimeter to check if one of the two is still good?
ps. the tda7293 are the original one's not the fake's
thanks for the reply
i've got two tda7293, pulled out of a power amplifier.
with the tda's in circuit the amp power light blinks and doesnt work nothing, but powering up the amp without the tda's(desoldered), it stay on and the power supply section works and the pre amp section too.
my question is:
is any way with a multimeter to check if one of the two is still good?
ps. the tda7293 are the original one's not the fake's
thanks for the reply
Just buy some new chips from here:
TDA7293V-E STMicroelectronics - Audio amplifier | Pout: 100W; MULTIWATT15; TDA7293V | TME - Electronic components
TDA7293V-E STMicroelectronics - Audio amplifier | Pout: 100W; MULTIWATT15; TDA7293V | TME - Electronic components
If you arent sure about them being fakes then you cant be sure about using them.
Simply buy from a reputable source and they are more likely to be OK.
Better to spend a little more and them being good than having to end up unsoldering them because they blew and risk damaging your pcb.
In the end you will probably have to buy the replacement from a better source.
Simply buy from a reputable source and they are more likely to be OK.
Better to spend a little more and them being good than having to end up unsoldering them because they blew and risk damaging your pcb.
In the end you will probably have to buy the replacement from a better source.