Very recently i purchased 6 CDIL 2n3055 transistors from a reputable indian online store (diyaudiocart). After receiving i took a multimeter/diode test & believe me among 6 transistors three is faulty. All new & genuine 3055. So as per my experience beware of second source like CDIL. Always buy world class transistors like from Onsemi, St & Toshiba.
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1st transistor symtom~ Failed diode test between base to emitter & base to collector.
2nd & 3rd transistor symtom~ Showing leakage between collector to emitter.
2nd & 3rd transistor symtom~ Showing leakage between collector to emitter.
There has always been a problem with fake parts and even respected distributors get caught, the current semiconductor shortage has only made things worse, there are plenty of fake onsemi, st and Toshiba parts out there.
Please describe what "failed" means to you.
What do you measure either way?
Numbers?
Leakage numbers and scale?
Can´t believe new transistors "show failures" under gentle couple volts applied by a Multimeter; normal is that they "work", sort of, only can´t stand or pass full voltage or current.
PS: are you measuring them "virgin", unused just pulled from the bag before mounting, or in-circuit or checking after some failure?
Have been bitten by fakes many times but nothing as gross as you describe, not even close.
I've unfortunately been supplied with fake 2N3055 by reputable suppliers. I've taken to cutting a batch sample open to look at the die inside before assuming the devices are not counterfeit and wasting time installing them in a circuit. You can't even see the minuscule die inside this photo of a fake below. These days I use MJ15003 instead, and I haven't been caught out - yet...
It can happen with genuine anything - even Motorola (ON), and even from “reputable” sellers. Less likely from authorized distributors with incoming QC. Got these from a reputable surplus dealer - and they ARE genuine. Bought 40 complementary pair, at 50 cents apiece. 8 had low enough hFE to be useless and two leaked enough that the breakdown measured six volts. Most were in spec and useable, so at that price I wasn’t going to complain. My guess is it was a rejected batch with too much spec fallout, and that’s why they ended up “surplus”. If it’s not an “authorized” distributor, they are not necessarily going get first rate parts.
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BEL and Keltron are better, CDIL are an old reputed company, try the transistors in circuit, I don't think anybody will bother to fake CDIL.
Best are BEL 2N3055HV....provided you get them.
Best are BEL 2N3055HV....provided you get them.
It seems to be a freak phenomenon. CDIL is a reputed company. There could be a manufacturing defect. You should return them to DAC and ask for refund. You could even contact CDIL sales team directly to verify where the stuff is genuine? I have experience of small and medium power transistors from CDIL and did not came with such an issue in past.
BTW I had come across a video on Youtube where in similar leakage between CE of a lot of 2N3773 of original BEL has been observed.
It is extremely dificult to get genuine 2N3055 and other components of Onsemi, St & Toshiba make in India unless you buy from a reputed seller like RS where the cost is exorbitantly high.
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Bel is only 10 Rupees more on DAC compared to CDIL, both are reputed...but BEL is bullet proof military grade, made from the silicon stage by one of the most integrated defense factories in the world.
Opinions and experience of BEL most welcome...
Opinions and experience of BEL most welcome...
🙂
Like I said above:
"Best are BEL 2N3055HV....provided you get them."
CDIL will not go bang I think. Try them in circuit with a series lamp.
Oh, a word of caution, or two:
1. Put best quality batteries in DMM, preferably alkaline, to get good results.
2. Use only Alkaline or high current rated power sources in pulse oximeters, and remove when not in use.
Most of them drain battery in off state, and you find out only at the most awkward time, tending to a sick person, and dead battery is frustrating, to put it mildly.
Like I said above:
"Best are BEL 2N3055HV....provided you get them."
CDIL will not go bang I think. Try them in circuit with a series lamp.
Oh, a word of caution, or two:
1. Put best quality batteries in DMM, preferably alkaline, to get good results.
2. Use only Alkaline or high current rated power sources in pulse oximeters, and remove when not in use.
Most of them drain battery in off state, and you find out only at the most awkward time, tending to a sick person, and dead battery is frustrating, to put it mildly.
I have had poor luck with CDIL and will not buy them. (This does not include power devices)
This is probably not a popular opinion, BUT,
some of the Eastern generics are much better, at least with respect to batch control.
This is probably not a popular opinion, BUT,
some of the Eastern generics are much better, at least with respect to batch control.
@tip33 100% original 2n3055 by CDIL.
I also hve some fake to-3 so i know which one is Good. Thinner/nail polish remover test is an easy way to know which one is genuine.
@JMFahey All new & virgin(unused).
I'm describing my multimeter test......
At first i set the meter at diode/continuty range~
(btw i hve two DMM, same result)
1st transistor symtom________
Red probe on Base & black probe on Emitter/Collector...."No reading"!! Same happens between Emitter(Red) to Base/Collector (black)which is normal.
But why no reading between base to emitter/collector?!
2nd & 3rd transistor symtom_______
Red probe on Collector & black on Emitter...showing some reading! Around 650-600! Slowly decreasing around 550. Leakage? when i change the probes Emitter(R) to Collector(B)...No reading, which is normal. But why reading between Collector to Emitter? Same happens in 2kohm/diode range on another meter.
**(1st transistor passed 2nd & 3rd transistor test & vice versa).
I also hve some fake to-3 so i know which one is Good. Thinner/nail polish remover test is an easy way to know which one is genuine.
@JMFahey All new & virgin(unused).
I'm describing my multimeter test......
At first i set the meter at diode/continuty range~
(btw i hve two DMM, same result)
1st transistor symtom________
Red probe on Base & black probe on Emitter/Collector...."No reading"!! Same happens between Emitter(Red) to Base/Collector (black)which is normal.
But why no reading between base to emitter/collector?!
2nd & 3rd transistor symtom_______
Red probe on Collector & black on Emitter...showing some reading! Around 650-600! Slowly decreasing around 550. Leakage? when i change the probes Emitter(R) to Collector(B)...No reading, which is normal. But why reading between Collector to Emitter? Same happens in 2kohm/diode range on another meter.
**(1st transistor passed 2nd & 3rd transistor test & vice versa).
@NareshBrd Yes i'll try them in circuit but knowing this abnormal behaviour i'm kinda reluctant to use these to-3 in JLH class-a. I've two dmm so meter is not a problem. New batteries.
Connect it across a 9v battery with an ammeter in circuit. Base open circuit. What current do you see. Now repeat with a 1k between base and emitter. What current now?
I'm guessing when you say "no reading" the DMM sticks at 1? Meaning O/C base. DMM diode tests usually put out about 2.5V and 1mA, so almost any transistor or diode (except a GaN LED perhaps) should pass that test. I take it that you have a diode or transistor you keep as a reference to check in these circumstances - I tend to have some components kept as reference such as a well calibrated resistor, capacitor or two and some trannys that are good examples.
I would probably send the three duds to CDIL - I don't know if they are known to be customer supportive but ask for replacements and tell them where you obtained them is the usual route. They can decide whether to investigate if they are "genuine" manufacturing escapees (i.e. as WGski says a batch of low spec parts sold onto the "cheap" market) or fakes. I guess if they are fakes they won't feel obliged to replace them.
It's a real pity that fake device manufacturers have not been closed down as it has been a problem for decades. But it would need international cooperation and rules. Which is why, of course, reputable companies now insist on purchasing systems with full traceability and certification to specs. (Even these are sometimes bypassed).
I would probably send the three duds to CDIL - I don't know if they are known to be customer supportive but ask for replacements and tell them where you obtained them is the usual route. They can decide whether to investigate if they are "genuine" manufacturing escapees (i.e. as WGski says a batch of low spec parts sold onto the "cheap" market) or fakes. I guess if they are fakes they won't feel obliged to replace them.
It's a real pity that fake device manufacturers have not been closed down as it has been a problem for decades. But it would need international cooperation and rules. Which is why, of course, reputable companies now insist on purchasing systems with full traceability and certification to specs. (Even these are sometimes bypassed).
CDIL are not worth faking...
Those would fetch a much higher price if marked as ST, On Semi etc. by a faker, particularly if the part was unobtanium.
Peculiar, as the seller - DAC - is also reputed of sorts.
Here I knew a motor maker who used Tata bearings, said he got them in the train from the factory, and NOBODY faked them (at that time, SKF was the leader, and fakes abounded). They were noisy, but durable, so he was comfortable.
Those would fetch a much higher price if marked as ST, On Semi etc. by a faker, particularly if the part was unobtanium.
Peculiar, as the seller - DAC - is also reputed of sorts.
Here I knew a motor maker who used Tata bearings, said he got them in the train from the factory, and NOBODY faked them (at that time, SKF was the leader, and fakes abounded). They were noisy, but durable, so he was comfortable.
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@john_ellis Yes, 1/OL. Ironically i've some fake to3 transistors(2n3773, 3055) & they all passed the test!! 😵
In addition i took a test of total 11-12 pair transistors including mjl21193/94, 2sc5200/1943 etc. All is fine except this three 2n3055
In addition i took a test of total 11-12 pair transistors including mjl21193/94, 2sc5200/1943 etc. All is fine except this three 2n3055
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