Motorola 2N3055 info and counterfeit watch

Brolik · Jan 7, 2011

I recently bought a small lot of what are supposed to be Motorola 2N3055 transistors to use in my Nevey projects. As I dug into the info on these pieces I found it very difficult to find any solid info at all, especially anything that helped to decide if they were counterfeit or not. So I figured I would collect together what I had and see if any of you infinitely wise souls can help me to decide what I have.

Some history and counterfeit info for the Motorola 2N3055:

https://groups.google.com/group/aus.electronics/browse_thread/thread/cd8d118ea634f5f/64e020b503c07b4e?lnk=st&q=motorola+on+2N3055&rnum=1&hl=en#64e020b503c07b4e
http://www.diyaudio.com/forums/parts/2848-2n3055-mj21193-mj15004-pics-detecting-counterfeits.html

Some pics of my transistors. 2 different serial numbers, mostly the 7826 with a few 7713:

one from the top of each serial number:

one from the bottom of each serial number (same sides):

an outside and inside shot of 7826:

Any ideas about the legitmacy of these transistors? real of fake?

peterc · Jan 7, 2011

http://sound.westhost.com/counterfeit.htm

Brolik · Jan 7, 2011

Thanks Peter, I had found that link and forgot to post it. Still, I feel a little unsure about it as there are no pictures of the inside of a legitimate 2N3055.

JohnRoberts · Jan 7, 2011

They look pretty real to me but I'm no expert. If you have a real 3055 to compare them to, maybe run them up on a curve tracer and/or make some basic characterizations (hfe, vbe@ some nominal current, etc). If they measure the same they should work the same.

If you don't have a real 3055 to compare them too, that's a little harder. IIRC pretty slow ft parts (200khz?) not very spectacular specs.

JR

thermionic · Jan 7, 2011

Wouldn't one from ON Semiconductor be made from the same die used by Motorola originally? Can't see why you'd fake a 2N3055 - a glamorous part it ain't. I've seen them in power supplies mostly - only Neve and Studer (IIRC) used them in the path.

J

JohnRoberts · Jan 7, 2011

thermionic said:
Wouldn't one from ON Semiconductor be made from the same die used by Motorola originally? Can't see why you'd fake a 2N3055 - a glamorous part it ain't. I've seen them in power supplies mostly - only Neve and Studer (IIRC) used them in the path.

J

I don't know who's making what these days. IIRC motorola sold their last TO-3 factory (in Mexico) to some group from down there and this was while i was still working at Peavey (and using lots of TO-3s). So more than a decade ago.

There were aluminum to-3s coming from Japan (Hitachi) for power mosfets and the like, but all those are gone now too (I think).

If people are willing to pay a premium price for cheap, lousy, old, steel, power transistors, somebody in china will answer the call. I'm surprised you don't upen up conterfeits and find plastic power devices inside. ;D

If those old devices were actually doing something that useful, it should be worth modeling it to replicate the transfer function with some modern parts.

JR

PS: Looking at those photos make me flash back to my first technician job back in the 60's where I often had to grind the top off of blown T0-3s to determine the failure mode. Typically a melted base wire, or voltage punch throughs between collector/emitter, that would leave a small melt mark where the short occurred. The 3055s were robust so harder to kill, but too slow to use in a switching supply like I was working on. I don't miss the old days.

PRR · Jan 7, 2011

> made from the same die used by Motorola originally?

No. 1960 3055 is an RCA part. First attachment tells how primitive things were. Motorola had different primitive processes.

The 1967 3055 is different from a 1977 3055. They were originally hometaxial, slow but rugged. All the hometaxial process machinery was thrown in the alley when epitaxial and Planar were developed to be better for 99% of all applications.

I did not know this at the time. It does explain why some 1960s amps using 2N3055 without real reliability issues were much less reliable in the 1970s.

ON Semi sure is using the Mototola style-sheet for the datasheets.

Fake? Those glass seals went out of style years ago; a causual copycat would just blob some epoxy in the hole. However that die is far smaller than we got in the 1960s. That large round area isn't just for looks.... the larger device dies half-filled it.

You can weed-out modern 3055s by holding 57V at 2 Amps for a dozen mS. Real stone-age 3055 will take it, effete quiche-eater 3055 will die. You can also try for 0.8mHz or 2.5MHz fT, though hFE is hard enough to measure without adding MHz to the mix, and you must use the original rating conditions.

PRR · Jan 7, 2011

Got a BIG curve-tracer? Old-old 3055 has high plate resistance.

PRR · Jan 7, 2011

haima · Jan 7, 2011

PRR said:
You can weed-out modern 3055s by holding 57V at 2 Amps for a dozen mS. Real stone-age 3055 will take it, effete quiche-eater 3055 will die.

I like it ;D

dagoose · Jan 8, 2011

I must seriously confess that somewhere at the beginning of the 80ties i had quite a lot of 3055's and i didn't know what to do with 'm and so i started blowing them up just for fun.. :

I think i will be banned for that.. or will you guys forgive me.. please? :-*

tommypiper · Jan 9, 2011

PRR said:
You can weed-out modern 3055s by holding 57V at 2 Amps for a dozen mS.

How does one apply this test? How do you calculate and control such a precise period of time to apply the voltage? It's not like counting to ten then throwing the switch off... How do you determine and control it to 2 Amps?

It may seem obvious to some, but I've never encountered this type of test before... :-\

Brolik · Jan 10, 2011

@JR - I feel for ya. It was NOT easy getting the top off that bad boy.

@PRR - Thanks. As always incredibly informative, even beyond my understanding. The concept of trying to burn them out intrigues me, so I think I'll give it a whirl (esp. as I have no curve tracer). How about if its more than a dozen ms. though? How about a dozen dozen, or even several thousand?

JohnRoberts · Jan 10, 2011

Brolik said:
@JR - I feel for ya. It was NOT easy getting the top off that bad boy.

Not that hard at all as I recall... grab the to3 with a pair of pliers, and grind the top off on a grinding wheel.

My speculation is that it was mostly make work from the junior engineer I was working for to get me out of his hair and stopped asking him questions. Even I, a lowly technician could easily predict with a Simpson 260 from resistance/V-drop measurements (same thing on an old 260 low ohms scale) whether I would find a melted base lead, or punched through collector region.

After the junior engineer I was working for finished his co-op stretch and went back to school full time a few months later, I had picked up enough OJT to finish the project (building preproduction prototype switching power supplies for a NAVY project) by myself.

JR

peter purpose · Jan 11, 2011

Here is what I believe to be a genuine 7926 3055.....

joe-electro · Jan 11, 2011

If that's a real 2N3055 then the ones on Ebay now are genuine. Here's what they look like inside:

.

Weird how the die is in a different place on each of these.

Joe

peter purpose said:
Here is what I believe to be a genuine 7926 3055.....

Brolik · Jan 11, 2011

both of your examples (Peter and Joe) make it look like the heat plate under the chip itself has a gold/copper hue. Is that just the quality of your lighting? Mine is distinctly the same color as the rest.

joe-electro · Jan 11, 2011

It's just the lighting. On mine, the actual color is pretty much the same as the underlying metal plate.

Joe

Brolik said:
both of your examples (Peter and Joe) make it look like the heat plate under the chip itself has a gold/copper hue. Is that just the quality of your lighting? Mine is distinctly the same color as the rest.

Brolik · Jan 11, 2011

awesome. So I shall infer that these are real Motorolas eh? Woohoo! I'll compile any other resources I can find on these units. Transistor Meta anyone?

joe-electro · Jan 11, 2011

I think it's a little premature to declare these as authentic. The die size looks too small and too modern to me. It also looks like the wires are aluminum, which is suspect. On the other hand, there was a shortage of copper in the late seventies, due to some country being mad at the US over something or other, so that might explain the copious use of aluminum in these transistors. I think more research is in order, a transistor (or maybe broaden it to a semiconductor devices) meta is an excellent idea, and this is a great topic to get it started. Or maybe start another forum dedicated to devices!

Joe

Brolik said:
awesome. So I shall infer that these are real Motorolas eh? Woohoo! I'll compile any other resources I can find on these units. Transistor Meta anyone?

Motorola 2N3055 info and counterfeit watch

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