Emitter resistors. These devices have suspiciously high Vce at high currents.
This forces sharing at low voltage/high current but is ineffective at high voltage/low current, hence the poor SOA above 30V, which basically becomes the single die case
Just got some more fakes from ASWO.
The 2SA1941 are definite fakes and have been tested to not meet Vceo(br) specifications, the 2SC5198 perform better voltage-wise but are likely fake too.
B-E capacitances are around 4.15nF for the 2SC5198 (3.84nF on a genuine), 1-1.5nF range for the 2SA1941 (3.51 on a genuine).
Paul
The 2SA1941 are definite fakes and have been tested to not meet Vceo(br) specifications, the 2SC5198 perform better voltage-wise but are likely fake too.
B-E capacitances are around 4.15nF for the 2SC5198 (3.84nF on a genuine), 1-1.5nF range for the 2SA1941 (3.51 on a genuine).
Paul
Anyone know where to get these? Honeywell Chart Recorder Rectifiers (4)- DB103G Rectifier! | eBay
Price is bit steep with shipping, since I only need one. Also is this suitable replacement? 1A DIL Bridge Rectifiers Pack 10 200V, 400V, 1000V Select type from menu | eBay
Price is bit steep with shipping, since I only need one. Also is this suitable replacement? 1A DIL Bridge Rectifiers Pack 10 200V, 400V, 1000V Select type from menu | eBay
Don't wire in 4 diodes! That's a messy repair that is often hard on the PCB traces. There isn't any reason to get exactly the right part. They are very common, so pick up a few.
Many parts distributors have a minimum order of $25. I'm sure you can find enough other stuff to make the order worthwhile.
-Chris
Many parts distributors have a minimum order of $25. I'm sure you can find enough other stuff to make the order worthwhile.
-Chris
Maybe this is something of help to get false transistor or mosfets discovered.
M328 LCD Transistor Tester Meter DIY Kit Square PWM Signal Generator F1Y2 | eBay
M328 LCD Transistor Tester Meter DIY Kit Square PWM Signal Generator F1Y2 | eBay
Hi everyone (Sorry for the bad english, but at least i'm trying hehehe)
Here my attemp to find some real TO-3 transistors here in Brazil, each one was buyed from different stores.
The MJ4502 is the heaviest from then, the "Malaysian" ones seem's like fake.
The MJ4502 have a thicker tab and the terminals have a finished and round tip
The other have a "cuted" end
Was too easy remove the cap from de 2N3055 and 2N3773, but as showed in the photo, was very difficult remove the cap from MJ4502
Is it very difficult to find 2N3055 or is it that the new ones from ST really are with the painted cover?
What are the minimum size of the die ? those of the photos are between 1.6 mm and 1.9 mm and the MJ4502 is about 4.5 mm
.
Here my attemp to find some real TO-3 transistors here in Brazil, each one was buyed from different stores.
The MJ4502 is the heaviest from then, the "Malaysian" ones seem's like fake.
The MJ4502 have a thicker tab and the terminals have a finished and round tip
An externally hosted image should be here but it was not working when we last tested it.
The other have a "cuted" end
An externally hosted image should be here but it was not working when we last tested it.
Was too easy remove the cap from de 2N3055 and 2N3773, but as showed in the photo, was very difficult remove the cap from MJ4502
Is it very difficult to find 2N3055 or is it that the new ones from ST really are with the painted cover?
What are the minimum size of the die ? those of the photos are between 1.6 mm and 1.9 mm and the MJ4502 is about 4.5 mm
.
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The 2n3773 is fake.
That die is about 20% of the size it should be.
There should be a copper slug similar to the 4502 at the end. You should be able to see the copper on the outside.
The copper slug in Toshiba from circa 1980 is even bigger than the MJ4502 shown.
The MJ4502 looks it might be genuine.
That die is about 20% of the size it should be.
There should be a copper slug similar to the 4502 at the end. You should be able to see the copper on the outside.
The copper slug in Toshiba from circa 1980 is even bigger than the MJ4502 shown.
The MJ4502 looks it might be genuine.
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All false except last motorola one, the wire to the die are sooo thin, needs to be as last one, and die is much to small, the 3055 are also not oke.
Unless you grind or attempt to machine the beryllium oxide you should be safe. Just handling those parts is perfectly safe.
How is the "M328 LCD Transistor Tester Meter" going to help you here beyond equipment a person might have already. I have one and find it compares well with the other 6 transistor testers I have. The only thing it does better is in comparison to some B&K testers. The M328 does a better job of identifying the proper leads. Beyond that, my HP LCR meter is the most effective instrument I have for detecting fakes - past the eyeball of course! I also have a 500 VDC power supply which is good at separating some fakes. In that case, the test is most assuredly destructive.
-Chris
How is the "M328 LCD Transistor Tester Meter" going to help you here beyond equipment a person might have already. I have one and find it compares well with the other 6 transistor testers I have. The only thing it does better is in comparison to some B&K testers. The M328 does a better job of identifying the proper leads. Beyond that, my HP LCR meter is the most effective instrument I have for detecting fakes - past the eyeball of course! I also have a 500 VDC power supply which is good at separating some fakes. In that case, the test is most assuredly destructive.
-Chris
Thank you so much guys !
I think MJ4502 is really genuine, i'll try buy more of them this weekend in the same store (physical store).
Now I really want some original 2N3055, it's very hard to find them.. Always this painted gray cap labeled as "ST"...
I know, the 2N3055 as an audio output device is not a "top quality", but most vintage receivers in Brazil had 2N3055 for amplifiers up to 45 W per channel.
I think MJ4502 is really genuine, i'll try buy more of them this weekend in the same store (physical store).
Now I really want some original 2N3055, it's very hard to find them.. Always this painted gray cap labeled as "ST"...
I know, the 2N3055 as an audio output device is not a "top quality", but most vintage receivers in Brazil had 2N3055 for amplifiers up to 45 W per channel.
Hi Rafael,
The 2N3055 was designed as a power supply pass transistor. It is pretty crappy for output transistors. Just because they did it cheap and nasty back then doesn't mean you should. Honestly, try to get some good output transistors and use them. If you can get the new On-Semi parts (who now make 2S and KS series parts), you're way ahead of the game.
Any of the MJW parts are great - as most of them are from On-Semi. I can't even see any reason even think of the 2N3055. Forget they ever existed, they weren't very good.
-Chris
The 2N3055 was designed as a power supply pass transistor. It is pretty crappy for output transistors. Just because they did it cheap and nasty back then doesn't mean you should. Honestly, try to get some good output transistors and use them. If you can get the new On-Semi parts (who now make 2S and KS series parts), you're way ahead of the game.
Any of the MJW parts are great - as most of them are from On-Semi. I can't even see any reason even think of the 2N3055. Forget they ever existed, they weren't very good.
-Chris