TA7317P IC issues
- Thread starter TomFowler
- Start date
ElectTech
Active Member
I can't tell from the picture if the IC is not fake. I suggest you check voltages in your equipment's Service Manual. Also, you should install an IC socket to check if any of the 5 new IC's work.
See here
I disagree. If one doesn't work it is almost certain all five are counterfeits. My two purchases were all fakes. Only NOS or ex-equipment will work because the chips aren't made anymore.
I will point out, again, that Consolidated is still offering these. (ebay seller ceitron - or ceitron.com if you want to work directly, though the website is funky and the S&H charges are high.)
If anyone has gotten unfit parts from ceitron, I earnestly sympathize, but please contact them to let them know. I believe that they (well, Steve, that is) will not knowingly offer unfit parts.
If anyone has gotten unfit parts from ceitron, I earnestly sympathize, but please contact them to let them know. I believe that they (well, Steve, that is) will not knowingly offer unfit parts.
Do the easy check here. If it passes you have a good or even genuine part. I am not aware of new production. Will check out Ceitron.
ElectTech
Active Member
I agree w/ you. I hadn't seen your test circuit. I wouldn't install a suspicious IC in my amplifier; you never know what can happen. Been there done that... A long time ago, I bought a bunch of cheap LM317 voltage regulators on ebay. I installed one, and it literally caught fire. They all went to the trash can. Never trusted unknown sellers and sources anymore. It is not about losing some 10 dollars; it is about the aggravations and risks involved.
reading when testing pins 1-4 what is your verdict ???? thanks
Attachments
933.3k? Do you see those diodes? Even without an answer on that I'd say counterfeit. It's three magnitudes of resistance. Test for those diodes to condemn them with certainty.
The Fuxtor
Addicted Member
I also bought some fake chips from eBay. Looked legit but no go. Ended up butchering a cheap JVC receiver and took it's chip to fix a Carver tfm-25
ElectTech
Active Member
I have a TA7317P that I bought almost 10 years ago from a trusted source, but I never needed it, and thus never tested it on a circuit. I just did a simple 'diode mode' test, and here are my measurements.
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The equivalent circuit doesn't show the 1k resistor from pin#1 to 4. It is an unique identifier for a legit chip.
Apart from the 1k resistor between pin#1 and 4 and the antiparallel diodes between pins#2 and 3 and pin#4 there is the substrate diode between pin#4 and 5 with its cathode on 5. Only if all these conditions are met you have a legit device.
Incidentally, I just got a bunch of counterfeit µPA68H dual N-JFETs. Got a full refund from Mr. Ma but this is getting ridiculous. Ordered a new batch, now with the marking "SINGAPORE" on them. Printed, not laser etched. It may happen, they promised to be "Original new 100% quality".
Incidentally, I just got a bunch of counterfeit µPA68H dual N-JFETs. Got a full refund from Mr. Ma but this is getting ridiculous. Ordered a new batch, now with the marking "SINGAPORE" on them. Printed, not laser etched. It may happen, they promised to be "Original new 100% quality".
ElectTech
Active Member
I hear you. When I have time, I will test my supposedly original, TA7317P on a breadboard. I only have a +/- 30 VDC Bench Power Supply, so I may have to change some components. I will use your idea of an LED in place of the relay and a 10k Ohm resistor in series with it. BTW, that counterfeit semiconductor fiasco reminds me of the 'home energy savings' magical boxes that are being sold out there (people pay like 10 dollars to see a lit LED on the wall outlet, that is all).
ElectTech
Active Member
Here it is. I built the circuit on a breadboard (I know, it is a mess). It passed the test. I made some circuit modifications to use a +/- 30 VDC power supply and to follow a circuit topology in my JVC A-X1 amplifier.
I tested: a) Disconnecting the -30 VDC supply, then the +30 VDC supply, then both. b) Introducing DC towards Pin #2. c) Varying the DC voltage towards Pin #1. The two TA7317P ICs that I have passed in all of these tests. If they are fake/replicas, they are good fake/replicas so far.
I tested: a) Disconnecting the -30 VDC supply, then the +30 VDC supply, then both. b) Introducing DC towards Pin #2. c) Varying the DC voltage towards Pin #1. The two TA7317P ICs that I have passed in all of these tests. If they are fake/replicas, they are good fake/replicas so far.
ElectTech
Active Member
Links to my tests:
TA7317P Test A
TA7317P Test B
BTW, I found in my archives the seller who sold me these chips. I bought it in 2018, and they shipped it from California to me in Florida.
TA7317P Test A
TA7317P Test B
BTW, I found in my archives the seller who sold me these chips. I bought it in 2018, and they shipped it from California to me in Florida.
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ElectTech
Active Member
I built a simulation in LTspice for the obsolete TA7317P speaker protection IC. @rcs16 Thanks for giving me the idea to use this freeware simulation tool.
I made assumptions about the type and value of the internal components because they were not given in the datasheet of the TA7317P. The simulation works as intended. For instance, you can inject DC in pins#2 or #3 or both, remove any of the power supplies, inject positive DC in pin#1, etc., and the circuit will not engage the speakers' relay (or the LED in this simulation) depending on the parameters acceptable to engage the relay. I hope someone can create a small PCB so people can make their own "discrete TA7317P compatible chip" to mitigate the problem of buying fakes. Thank you.
Notes:
1- Perhaps Q13 (2N2222) is too weak to drive some big relay coils. The original TA7317P can supply up to 130 mA to the relay coil; the 2N2222 at saturation can as well, but I would use a more robust transistor for big relays.
I made assumptions about the type and value of the internal components because they were not given in the datasheet of the TA7317P. The simulation works as intended. For instance, you can inject DC in pins#2 or #3 or both, remove any of the power supplies, inject positive DC in pin#1, etc., and the circuit will not engage the speakers' relay (or the LED in this simulation) depending on the parameters acceptable to engage the relay. I hope someone can create a small PCB so people can make their own "discrete TA7317P compatible chip" to mitigate the problem of buying fakes. Thank you.
Notes:
1- Perhaps Q13 (2N2222) is too weak to drive some big relay coils. The original TA7317P can supply up to 130 mA to the relay coil; the 2N2222 at saturation can as well, but I would use a more robust transistor for big relays.