MJ15025 transistors wrong polarity!!!!!!!!!! - Page 1
Forum section: electronics / general

author: ddelectrical
author_rank: Contributor
timestamp: July 31, 2016, 05:16:03 pm
content: Warning to those buying "1pair 1x MJ15024G + 1x MJ15025G MJ15024 MJ15025 ORIGINAL Audio power Transistor" this from fleabay. The whole batch are all NPN!!!!! There are no PNP type in my order. The label on the PNP's is a misprint. Can pm sellers name if requested. The wording above is the exact ad title. Buyer beware.

author: TheAmmoniacal
author_rank: Unknown
timestamp: July 31, 2016, 05:57:35 pm
content: Can you be more concise about your problem? Did you receive two transistors? One MJ15025G and one MJ15024G? But you think both are actually MJ15024G? Or did you receive two MJ15024G?

author: ddelectrical
author_rank: Contributor
timestamp: July 31, 2016, 06:15:19 pm
content: Hi, Yes, sorry. I ordered six pairs of complementary transistors, (6 x MJ15024G and 6 x MJ15025G). Supposed to be NPN and PNP respectively. They are all NPN. The PNP type are mis-labled on the cans. Apologies for confusion.

author: TheAmmoniacal
author_rank: Unknown
timestamp: July 31, 2016, 06:16:21 pm
content: Quote from: ddelectrical on July 31, 2016, 06:15:19 pmHow did you check / determine this?

author: ddelectrical
author_rank: Contributor
timestamp: July 31, 2016, 06:20:52 pm
content: First with an Atlas transistor tester then confirmed by diode test function on DMM. Yep - all NPN! Test test test............

author: amyk
author_rank: Super Contributor
timestamp: July 31, 2016, 10:22:19 pm
content: Probably not original either, just some generic NPN transistor die.

author: rsjsouza
author_rank: Super Contributor
timestamp: July 31, 2016, 10:33:55 pm
content: In this case I would suspect that both transistor types you bought do not meet the specifications of an original MJ... In other words, fake transistors all around.

author: wraper
author_rank: Unknown
timestamp: July 31, 2016, 10:39:49 pm
content: Quote from: ddelectrical on July 31, 2016, 06:15:19 pmBoth types you have bought are fakes with 95+% probability.

author: Ian.M
author_rank: Super Contributor
timestamp: July 31, 2016, 11:37:35 pm
content: *ANY* flanged metal TO-3 or TO-66 package transistor on EBAY that isn't in an identifiable original dusty faded NOS box bag or blister pack is probably fake. There are sufficient AudioPhools out there to make faking them popular, and all that's needed to fake them is a supply of *anything* in the right package, paint stripper and/or metal polish to remove the old markings and an ink stamp to re-mark with a fake number, batch code and logo. Its well within the capabilities of any 3rd world board-roasting component 'recycler'.

author: M4trix
author_rank: Frequent Contributor
timestamp: July 31, 2016, 11:39:02 pm
content: Quote from: wraper on July 31, 2016, 10:39:49 pm+1Yep, I would say they're even 100% fake ! @ddelectrical, please post the link or some pictures of those transistors. I'm specialized for counterfeits especially for TO-3 package transistors.Well, if you have time and a hacksaw, try to 'peel' off the top. I bet there will be 2 small paralleled dies covered with white silicon glue. Been there, done that mate.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: August 01, 2016, 12:13:26 am
content: Hi,To the original poster, it would be good to cut the top off one of the transistors and take a picture of the silicon die.There are many ways to open them. My favorite is to file around the edge of the top with file at 45 degrees.Here is a picture of a MJ15025 (PNP) that I am 99.99% sure is genuine. I bought a bag of them locally, the date code is 9228, the 28th. week of 1992.Look at the size of the silicon die.Notice that there are two emitter leads and one base lead coming from the die to the pins.Note that the die is mounted on a heat spreader.I have shown you mine, now let's see yours ....Regards,Jay_Diddy_B

author: M4trix
author_rank: Frequent Contributor
timestamp: August 01, 2016, 08:24:49 pm
content: Where did @ddelectrical disappear now ?

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: August 01, 2016, 08:58:57 pm
content: Quote from: M4trix on August 01, 2016, 08:24:49 pm1+I was looking forward to seeing pictures of his naked transistors....Regards,Jay_Diddy_B

author: hans
author_rank: Super Contributor
timestamp: August 01, 2016, 09:57:10 pm
content: There is probably not enough silicon to photograph /sSeriously, I would expect any chinese product from Ebay with silicon in it, to have at least 1 fake/dodgy component in it.Last week I bought a few MPU6050 boards for 1.75$ each. That includes a small PCB with the MEMS, voltage regulator, passives, pre-assembled and comes with 2 unmounted pin headers in an (presumably) ESD bag.I can also buy 1 MPU6050 chip from Farnell 18.82 euro incl VAT. Or if I buy 2000, 8.20 EUR, EACH.Go figure. It's probably not a MPU6050, but a clone that's "protocol compatible", likely with worse specs. You get what you pay for

author: CJay
author_rank: Super Contributor
timestamp: August 02, 2016, 06:53:35 am
content: Quote from: hans on August 01, 2016, 09:57:10 pmOr, possibly a genuine part that's one of a few tens/hundreds of thousands that were destined for the internals of a cell phone before it got superseded by a newer, better, smaller or cheaper version.It's quite interesting to see the modules appearing on eBay that use chips intended for cell-phone or tablet use, the market moves so fast and drives the technology, leaving us with the overstock to hoover up cheap.

author: wraper
author_rank: Unknown
timestamp: August 02, 2016, 07:06:14 am
content: Quote from: hans on August 01, 2016, 09:57:10 pmThat's highly overpriced for what it is. That sensor is for smartphones, tablets and other consumer devices. Even at $2 barely anyone would use it in high volume products.

author: ddelectrical
author_rank: Contributor
timestamp: August 02, 2016, 07:15:11 pm
content: Hi all. Thanks for the great replies. New batch ordered from Mouser already! So, I will have a look in these cans this week some time. I am new to the board and really appreciate the feedback. Will try to get some naked transistor pics posted soon. Is that kind of thing even allowed on here? LOL. Very busy schedule here so please be patient. Thanks again.

author: JoeO
author_rank: Frequent Contributor
timestamp: August 03, 2016, 01:33:07 am
content: Quote from: ddelectrical on August 02, 2016, 07:15:11 pmTransistor porn - Can't wait.

author: Jwalling
author_rank: Unknown
timestamp: August 03, 2016, 10:05:18 am
content: Quote from: M4trix on July 31, 2016, 11:39:02 pmI suspect the listing is this one:http://www.ebay.com/itm/1pair-1x-MJ15024G-1x-MJ15025G-MJ15024-MJ15025-ORIGINAL-Audio-power-Transistor-/251672882415?hash=item3a98df6cef:g:neMAAOxyQfJTfEh7Some other feedbacks also suggest that the occasional fake gets sold:http://feedback.ebay.com/ws/eBayISAPI.dll?ViewFeedback2&userid=huayi-components&iid=251672882415&de=off&items=25&searchInterval=30&which=negative&interval=365&_trkparms=negative_365Jay

author: ddelectrical
author_rank: Contributor
timestamp: August 05, 2016, 05:59:59 am
content: Er, hmmm. Not much in there then.Made from pure high quality bullshit in fact. What a waste of metal! Inside picture is next message. Not sure how to get two images on one post.

author: ddelectrical
author_rank: Contributor
timestamp: August 05, 2016, 06:01:17 am
content: Here:

author: Whales
author_rank: Super Contributor
timestamp: August 05, 2016, 07:10:24 am
content: Oh wow. I wonder what the bond wire are made of!

author: AntiProtonBoy
author_rank: Frequent Contributor
timestamp: August 05, 2016, 07:14:41 am
content: Quote from: ddelectrical on July 31, 2016, 05:16:03 pmName and shame, dude. People selling dodgy shit do not deserve anonymity.

author: blacksheeplogic
author_rank: Frequent Contributor
timestamp: August 05, 2016, 07:24:10 am
content: Quote from: AntiProtonBoy on August 05, 2016, 07:14:41 amMuch of the time you get what you pay for.

author: Jwalling
author_rank: Unknown
timestamp: August 05, 2016, 09:29:50 am
content: Quote from: ddelectrical on August 05, 2016, 06:01:17 amIs the "die" even made of silicon?Jay

author: amyk
author_rank: Super Contributor
timestamp: August 05, 2016, 11:03:58 am
content: They look real enough as in they are actually transistors, but not as transistors of the right specs. The die is about the right size to go into a TO-220.

author: Ian.M
author_rank: Super Contributor
timestamp: August 05, 2016, 11:23:41 am
content: In a TO-220? <LOL>The die is only slightly larger than the lead diameter. It looks like something that one would expect in a TO-92.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: August 05, 2016, 11:37:49 am
content: Hi,In my first job at Gould Advance Power Supply Div, Bishops Stortford, U.K. in the late 1970s. They had made a display of de-capped 2N3055 transistors.I can't remember how many manufacturers were on this display, but there were maybe 7-8. The manufacturers were arranged on one axis and they had date codes on the other axis.They used this to illustrate that there was not only a difference between manufacturers but how they changed over time. Hint, they did not get better.The JEDEC spec only required a small subset of the published specifications to met, to call a transistor a 2N3055.There were variations in:1) die size2) number and quantity of bonding wires. The old RCA parts had metal clips !!3) The use of a heat spreader.4) Case material, steel or copper.To counteract this issue, transistors like 2N3772 were specified for use.The other reason for being more specific, was FBSOA, varied considerably. This important for transistors being operated in the linear region.I have been de-capping transistors ever since.The picture posted by ddelectrical, is a very small die for a T0-3 package. I would like to put those on a curve tracer and see what kind of specs that they had. At the price they are I might just buy some...I really encourage people who receive fake transistors to leave negative feedback. This way they are doing a service to those coming after them.Regards,Jay_Diddy_B

author: rsjsouza
author_rank: Super Contributor
timestamp: August 05, 2016, 11:41:15 am
content: Quote from: Ian.M on August 05, 2016, 11:23:41 amThe TO-220 transistors I have disassembled (TIP31s, TIP 42s, TIP120s, TIC106Ds, TIC226Ds, etc.) had about this die size. I would expect a TO-92 to be a lot smaller (about the size of a LED substrate).

author: Ian.M
author_rank: Super Contributor
timestamp: August 05, 2016, 12:05:52 pm
content: I did a bit of scaling from the image to compare the die size to the mounting holes. The die is 2mm square, about double the size of the die from a a typical 5mm dia resin encapsulated LED. Jay_Diddy_B's die is 5.2mm square, 6.7 times the area.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: August 05, 2016, 02:06:58 pm
content: Quote from: Ian.M on August 05, 2016, 12:05:52 pmRemember we are dealing withArea.so 2 x 2 = 4versus5 x 5.5 = 27.5 (quickly measured from my original part)so the ratio of area 4 : 27.5 about 7xso the small die is about a 3A part.Regards,Jay_Diddy_B

author: M4trix
author_rank: Frequent Contributor
timestamp: August 05, 2016, 03:07:49 pm
content: Quote from: AntiProtonBoy on August 05, 2016, 07:14:41 am+1Sellers who sell this stuff have to be exposed in public ! Well, as I expected, a small die covered with glue. You don't even need to open the can. Just look at those wrong marking fonts and those rough edges all around the base plate.

author: ddelectrical
author_rank: Contributor
timestamp: August 05, 2016, 04:41:08 pm
content: Seller:http://www.ebay.co.uk/usr/huayi-componentsFake as a wedding cake.Rip off merchant.

author: M4trix
author_rank: Frequent Contributor
timestamp: August 05, 2016, 05:26:50 pm
content: Top rated seller, 99.6% positive feedback...

author: wraper
author_rank: Unknown
timestamp: August 05, 2016, 05:33:30 pm
content: Quote from: ddelectrical on August 05, 2016, 04:41:08 pmWhat I've seen right away, for sale 100% fake flux only:http://stores.ebay.co.uk/huayi-components/_i.html?_nkw=flux&submit=Search&_sid=1097190996

author: wraper
author_rank: Unknown
timestamp: August 05, 2016, 05:36:34 pm
content: Fake AD797http://www.ebay.co.uk/itm/5pcs-AD797BR-AD797-Ultralow-Distortion-Ultralow-Noise-Op-Amp-/251245225985

author: M4trix
author_rank: Frequent Contributor
timestamp: August 06, 2017, 11:57:45 pm
content: Quote from: wraper on August 05, 2016, 05:33:30 pmI had to bump this thread. Look at the labels. They didn't even care about the writing mistakes !http://www.ebay.co.uk/itm/100g-AMTECH-RMA-223-UV-Flux-Soldering-Paste-New-/251654570831?hash=item3a97c8034f