MCM just put $77.92 back into my bank account for the bad transistors I ordered from them, which was my LAST order from them. I also noticed that MCM is tied to Newark Electronics some how, so add that vendor to the ever growing list.
Craig
Craig
Hi Fred,
Yes, if you got good readings from testing a transistor, you also know the pin-out. There are some J-Fets (most actually) that work fine with the source and drain swapped. It's always handy to look the part up if there is any questions about pin-out. With J-Fets you can identify the gate with certainty, same with the base on a BJT, by using the diode test on your multimeter. You also know the polarity of the device if you have figured out which lead on the meter is positive in diode test. This is useful to know when you are troubleshooting something.
Hi Steve,
B&K made the 520 and 530 transistor testers that were supposed to identify transistor leads. They even have a fancy colour coded set of leads and a nifty lever that is supposed to tell you what terminal is connected to what colour. You can not trust those testers at all. I have both models in my stable of testers. The IT-18 wins hands down, even though it doesn't test J-Fets. Don't ask me how much the 530 cost me, but I'll tell you it was more than a good tube tester.
Hi David,
Yeah, MCM was never a trustworthy place unless you were buying plate resistors or some other commodity that was not worth cloning. An ohmmeter would quickly point these fakes out if the appearance didn't first.
Hi Craig,
I have purchased just about every type of part from Newark over the years. The only things I don't care for is their higher shipping and extra transit day when compared to Digikey. I have never had a defective part (or copy) delivered to me from Newark. You have to watch that you don't jump to conclusions.
There is a plant in China that is making some of the old transistor numbers that have been discontinued everywhere else. They are not fakes, or renumbered parts because the company logo is clearly marked on the cases. Whether or not these are good parts is an entirely different question. It is entirely possible that Farnell / MCM are selling these parts. They will look different, the markings will be different but these are legitimate parts. They may (or may not) match the original performance of the devices they replace.
So Craig, did you notice a company name or trade mark on those transistors?
-Chris
Yes, if you got good readings from testing a transistor, you also know the pin-out. There are some J-Fets (most actually) that work fine with the source and drain swapped. It's always handy to look the part up if there is any questions about pin-out. With J-Fets you can identify the gate with certainty, same with the base on a BJT, by using the diode test on your multimeter. You also know the polarity of the device if you have figured out which lead on the meter is positive in diode test. This is useful to know when you are troubleshooting something.
Hi Steve,
B&K made the 520 and 530 transistor testers that were supposed to identify transistor leads. They even have a fancy colour coded set of leads and a nifty lever that is supposed to tell you what terminal is connected to what colour. You can not trust those testers at all. I have both models in my stable of testers. The IT-18 wins hands down, even though it doesn't test J-Fets. Don't ask me how much the 530 cost me, but I'll tell you it was more than a good tube tester.
Hi David,
Yeah, MCM was never a trustworthy place unless you were buying plate resistors or some other commodity that was not worth cloning. An ohmmeter would quickly point these fakes out if the appearance didn't first.
Hi Craig,
I'm going to have to disagree with you on this. Newark is "A Premier Farnell Company" as far as this notation at the top, right corner of their home page. I suspect that MCM was purchased by the same umbrella company. They are two different operations.
I have purchased just about every type of part from Newark over the years. The only things I don't care for is their higher shipping and extra transit day when compared to Digikey. I have never had a defective part (or copy) delivered to me from Newark. You have to watch that you don't jump to conclusions.
There is a plant in China that is making some of the old transistor numbers that have been discontinued everywhere else. They are not fakes, or renumbered parts because the company logo is clearly marked on the cases. Whether or not these are good parts is an entirely different question. It is entirely possible that Farnell / MCM are selling these parts. They will look different, the markings will be different but these are legitimate parts. They may (or may not) match the original performance of the devices they replace.
So Craig, did you notice a company name or trade mark on those transistors?
-Chris
Chris
I searched for 2SA1494s on the Newark site for which they had two listed, one was from MCM. How they are connected I don't know. The transistors looked OK from the outside but were very different on the inside, maybe they changed the design. Going to try a different vendor, B and D Electronics, they "assured" me that the transistors will be original Sanken. We'll see. I've never had this problem before, been dealing with MCM for at least 20 years.
Craig
I searched for 2SA1494s on the Newark site for which they had two listed, one was from MCM. How they are connected I don't know. The transistors looked OK from the outside but were very different on the inside, maybe they changed the design. Going to try a different vendor, B and D Electronics, they "assured" me that the transistors will be original Sanken. We'll see. I've never had this problem before, been dealing with MCM for at least 20 years.
Craig
Hi Craig,
I just lost a longish post.
In a nutshell, order Fairchild or On Semi equivalent parts. You will know for sure what they are. Buy only from authorized distributors / dealers.
I have seen "MCM" branded parts at Newark, but I refuse to buy them.
-Chris
I just lost a longish post.
In a nutshell, order Fairchild or On Semi equivalent parts. You will know for sure what they are. Buy only from authorized distributors / dealers.
I have seen "MCM" branded parts at Newark, but I refuse to buy them.
-Chris
quote:
In the past, MCM has sold counterfeit ON Semiconductor parts.
I will second that as I have been burned bad buying transistors from them.
Never been burned by anything I purchased from Mouser. I buy everything from them now.
In the past, MCM has sold counterfeit ON Semiconductor parts.
I will second that as I have been burned bad buying transistors from them.
Never been burned by anything I purchased from Mouser. I buy everything from them now.
Hi djk, 6BG6GA,
You know, I'm not trying to defend MCM at all. Just overcompensating for my own distrust and trying not to talk them down since I have no personal experience with them. I am so shocked that MCM was stupid enough to sell counterfeit On Semi parts just blows me away! If they were an authorized distributor, they sure won't be now!
As shocked as I am that a large retailer dealt in forgeries, I'm also wondering about the timing of these events. Maybe that's why Farnell was able to buy them in the first place? My god, was that ever a stupid move on MCM's part! I'm having trouble understanding how this could possibly have seemed like a good idea in a small world.
Okay, so MCM should be frozen out as far as a supplier then. Once they have done this once, it'll be easier for them to cross that line again in the future. Wow.
On the other hand, Newark has never sold me anything over a great many years that wasn't as it was described. Some pricing can be cheaper than other vendors and you pretty much have to look at price break points to figure out where to buy. I know some stores are pretty much aimed at onesy-twosy type business, while other vendors give decent breaks at 10 pieces. Newark should be a pretty solid place to buy, and more attractive for Canadian customers than Mouser is. I think they still want $20 to ship to Canada. Of course, that's much better than they were a couple years ago. Digikey is still the most friendly place to buy from for Canadians.
I guess MCM does not deserve to be in business then, they've lost the trust.
-Chris
You're kidding!!
You know, I'm not trying to defend MCM at all. Just overcompensating for my own distrust and trying not to talk them down since I have no personal experience with them. I am so shocked that MCM was stupid enough to sell counterfeit On Semi parts just blows me away! If they were an authorized distributor, they sure won't be now!
As shocked as I am that a large retailer dealt in forgeries, I'm also wondering about the timing of these events. Maybe that's why Farnell was able to buy them in the first place? My god, was that ever a stupid move on MCM's part! I'm having trouble understanding how this could possibly have seemed like a good idea in a small world.
Okay, so MCM should be frozen out as far as a supplier then. Once they have done this once, it'll be easier for them to cross that line again in the future. Wow.
On the other hand, Newark has never sold me anything over a great many years that wasn't as it was described. Some pricing can be cheaper than other vendors and you pretty much have to look at price break points to figure out where to buy. I know some stores are pretty much aimed at onesy-twosy type business, while other vendors give decent breaks at 10 pieces. Newark should be a pretty solid place to buy, and more attractive for Canadian customers than Mouser is. I think they still want $20 to ship to Canada. Of course, that's much better than they were a couple years ago. Digikey is still the most friendly place to buy from for Canadians.
I guess MCM does not deserve to be in business then, they've lost the trust.
-Chris
Looks like I'm the next victim of MCM counterfeits. I did the high voltage breakdown test Pete recommended on the MCM 2912 I had installed to replace Q4 (160v C to E, B open) and measured 5.46 amps! (119.6 volts across a 21.9ohm resistor). I did the same test on a 2912 from B&D and measured 0.
If this entire saga is due to a counterfeit, I will have learned a very valuable lesson, and I will be very, very unhappy with MCM.
I'm going to proceed slowly, as recommended. I'm going to reinstall Q4 using the B&D part this time, replace R16 and then test Q3 and Q4 to make sure they are working properly as current sources at full voltage (as Pete recommended in post #530).
While I'm at it, I'm going to swap out the MCM-supplied Q7 with a replacement from B & D. And I'll go through and make sure I don't have any other MCM-supplied tr's on the board. Sheesh. Someone needs to tell Newark to stop selling MCM, or their rep will get dragged down too!
If this entire saga is due to a counterfeit, I will have learned a very valuable lesson, and I will be very, very unhappy with MCM.
I'm going to proceed slowly, as recommended. I'm going to reinstall Q4 using the B&D part this time, replace R16 and then test Q3 and Q4 to make sure they are working properly as current sources at full voltage (as Pete recommended in post #530).
While I'm at it, I'm going to swap out the MCM-supplied Q7 with a replacement from B & D. And I'll go through and make sure I don't have any other MCM-supplied tr's on the board. Sheesh. Someone needs to tell Newark to stop selling MCM, or their rep will get dragged down too!
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Q4 is a NPN transistor. I hope you meant you did a C to E, B open, (CEO). That is C to positive rail and E to negative rail.
David.
Yep, that's exactly how I did it, measuring Lceo. Sorry if that was vague before. I edited the post.
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I've never ordered from MCM. I got most of my part from Main electronics in Vancouver.
Main electronics has absorbed the stock from about fifty different shops that have closed there doors over 30 years. So I was able to get OEM stock, albeit rather old stock.
I think by now it is rather depleted so I wouldn't outright trust them anymore.
However, Q4 being bad explains the problems you've been having.
David.
Main electronics has absorbed the stock from about fifty different shops that have closed there doors over 30 years. So I was able to get OEM stock, albeit rather old stock.
I think by now it is rather depleted so I wouldn't outright trust them anymore.
However, Q4 being bad explains the problems you've been having.
David.
Hi Fred,
I've always heard about fakes, but I've never been burned myself. Sorry to hear about your experience here.
By all means, call Newark back and relate the story to them. They should remove everything branded "MCM" without delay. To tell you the truth, I have been tempted to try some of these "MCM" parts out, but only because Newark carried them. I figured they had to be okay. My little voice saved me.
-Chris
I've always heard about fakes, but I've never been burned myself. Sorry to hear about your experience here.
By all means, call Newark back and relate the story to them. They should remove everything branded "MCM" without delay. To tell you the truth, I have been tempted to try some of these "MCM" parts out, but only because Newark carried them. I figured they had to be okay. My little voice saved me.
-Chris
Yeah, I'll call Newark. But first I'll call MCM and ask them for at least a refund. I'll be polite, but firm. At least I'll start out polite and see what that gets me... 😀
Sometimes the little voice is very helpful.
Hi Fred,
Yes. I always get much further by remaining calm. Having all your facts in a row also helps.
It's really too bad you can never get more than the value of the part for your trouble. Especially since this is not an odd defect, but rather a systematic rip-off. My own impression is that someone knowingly is allowing these out. If not, then "due diligence" has not been followed.
I'm the last guy to recommend damages exceeding a part(s) and shipping, but in this case I feel there is neglect on their part. A class action suit would be the right medicine here. For those who know me, this suggestion is out of my normal character.
-Chris
Yes. I always get much further by remaining calm. Having all your facts in a row also helps.
It's really too bad you can never get more than the value of the part for your trouble. Especially since this is not an odd defect, but rather a systematic rip-off. My own impression is that someone knowingly is allowing these out. If not, then "due diligence" has not been followed.
I'm the last guy to recommend damages exceeding a part(s) and shipping, but in this case I feel there is neglect on their part. A class action suit would be the right medicine here. For those who know me, this suggestion is out of my normal character.
-Chris
As you have it now is fine, I'd use the 100 ohm current limiters at the fuse holders.
P1 min resistance of course.
"I guess MCM does not deserve to be in business then, they've lost the trust."
The details are at the Leach site.
MCM sold a transistor represented to be an ON Semiconductor device, a device that ON had discontinued, and was not even the correct polarity.
The details are at the Leach site.
MCM sold a transistor represented to be an ON Semiconductor device, a device that ON had discontinued, and was not even the correct polarity.
Hi Chris,
You asked about a On Semi part number I mentioned a while back NJL0281G and one you mentioned I think it was MJL0281A which you said was discontinued.
I came across another DIY post that listed the meaning of On Semi's prefixes. The prefixes apparently represent the case style packaging. So I'm thinking maybe On Semi just repackaged the MJL0281A.
David.
You asked about a On Semi part number I mentioned a while back NJL0281G and one you mentioned I think it was MJL0281A which you said was discontinued.
I came across another DIY post that listed the meaning of On Semi's prefixes. The prefixes apparently represent the case style packaging. So I'm thinking maybe On Semi just repackaged the MJL0281A.
David.
Thanks Pete! I thought so, but I don't trust my assumptions yet.
Okay then, here are the results:
Test set up as follows:
Q4C---1kohm---(+) supply
and Q3C---1kohm---(-) supply
Measured voltage drop across each of the 1kohm resistors as follows:
@25vdc on the supply: 4.46ma (+ side); 1.84ma (- side)
@50vdc: 4.83ma (+); 1.88ma (-)
@80vdc: 5.24ma (+); 1.93ma (-)
Obviously I was able to go full voltage without smoking R16 again or noting any oscillation. Current draw at the variac was less than .1a. All seems well so far...
Next baby step?