Hi Fred,
Yes, the MCM part is an older production part, but real. It's interesting to see really old parts being sold by MCM. Not what I would expect. I guess the real question is .. where did those older parts come from?
Hi David,
Yes, those designs could be very unstable. There is gain in the output stage in many of these designs. Bypass capacitors are critically important with these. Use non-inductive emitter resistors as well. You may even need to use base stoppers with some.
Hi Pete,
I've worked on quite a few similar amplifiers, and they all share the same tendency to oscillate. The stacked output stage is even more susceptible than a normal E-F stage.
-Chris
Yes, the MCM part is an older production part, but real. It's interesting to see really old parts being sold by MCM. Not what I would expect. I guess the real question is .. where did those older parts come from?
Hi David,
Yes, those designs could be very unstable. There is gain in the output stage in many of these designs. Bypass capacitors are critically important with these. Use non-inductive emitter resistors as well. You may even need to use base stoppers with some.
Hi Pete,
I've worked on quite a few similar amplifiers, and they all share the same tendency to oscillate. The stacked output stage is even more susceptible than a normal E-F stage.
-Chris
Perhaps I said it wrong, but what I meant to communicate is that if there is a problem with a product (ICs and CAPs do have a certain defective rate that we cannot control or test for), I would certainly prefer people to contact us directly and allow us to set it right before they assume that we are in the business of ripping people off and then make those statements on websites. We stock over 40,000 unique parts and on some items we process multiple receivings every month. I can't remain competitve and have enough staff to fully test and inspect every product that we receive. We have to rely on our supply chain and then verify where possible or if we have specific problems. Our buyer for these product categories has issued an alert to all of our suppliers of these products and we will begin inspecting receipts from the supplier of the items referenced herein for a period of time. Our tech support people and customer service people have been asked to relay any information they get back to our buyers quickly so that we can attempt to isolate any problem and rectify it.
MCM is part of Premier Farnell and therefore is a sister company of Newark, Farnell, etc. We are located in 23 countries throughout the world and we all have a lot of pride in serving our customers well. Even being as big as we are, we have had this problem in all divisions of the company. It's not an excuse, it's just a bit of a reality that this happens and we try to avoid it -- however, we also have to balance how much we can spend to root it out 100%. Part of our unique selling proposition at MCM is having hard-to-find parts. That means that we also work through brokers and agents to source things our customers need and this creates some adidtional challenges.
I appreciate being part of the discussion.
I don't believe that MCM is in the business of purposefully ripping people off, and I hope I never implied any such thing. I will say that they have been very responsive to me and my issue, and will be refunding me for the bad parts and even for a set of probes that melted while testing said bad parts. They have been proactive (they called me first!) and very apologetic.
I appreciate that they are stocking hard-to-find parts, and that this brings with it issues of authenticity (Chris, I suspect that many of these "old" parts are actually "re-manufactures" that are made by third parties, hopefully under license or some agreement with the OEM).
That said, does getting back the handful of dollars that is the cost of the parts come close to compensating me, and everyone else here, for all the time and effort (not to mention cost of other parts purchased for troubleshooting)? No, of course not. Not even close. And yes, as Pete pointed out, my input board is knackered from all de-soldering and re-soldering (see the attached pic of a repair I had to make to a worn-out trace on Q4, one of the bad parts).
Obviously, it's not reasonable to expect MCM to reimburse me for any of that. Nor could they reimburse me for the self-doubt and frustration that I experienced trying to figure out what could be wrong. Seems to me the solution has to come from avoiding the problem in the first place.
I would gladly pay a premium for a part that is 100% guaranteed tested and genuine. I bet other people would too. Doing those tests would also allow MCM to offer parts matching, a service many DIYers would appreciate greatly. I would also pay more for a guarantee that covered more than parts replacement. For example, Kryptonite bike locks have long had a warranty that, in the event of a theft when their lock was being used, would replace not just the lock but the stolen bicycle (up to a certain amount) as well. Could a similar warranty work for select electronic parts?
I'm sure there are other potential solutions, but I don't really know this business very well. Anyway, that's Mr Minix's job! All I do know for sure is that the current model doesn't work very well for consumers like me.
I appreciate that they are stocking hard-to-find parts, and that this brings with it issues of authenticity (Chris, I suspect that many of these "old" parts are actually "re-manufactures" that are made by third parties, hopefully under license or some agreement with the OEM).
That said, does getting back the handful of dollars that is the cost of the parts come close to compensating me, and everyone else here, for all the time and effort (not to mention cost of other parts purchased for troubleshooting)? No, of course not. Not even close. And yes, as Pete pointed out, my input board is knackered from all de-soldering and re-soldering (see the attached pic of a repair I had to make to a worn-out trace on Q4, one of the bad parts).
Obviously, it's not reasonable to expect MCM to reimburse me for any of that. Nor could they reimburse me for the self-doubt and frustration that I experienced trying to figure out what could be wrong. Seems to me the solution has to come from avoiding the problem in the first place.
I would gladly pay a premium for a part that is 100% guaranteed tested and genuine. I bet other people would too. Doing those tests would also allow MCM to offer parts matching, a service many DIYers would appreciate greatly. I would also pay more for a guarantee that covered more than parts replacement. For example, Kryptonite bike locks have long had a warranty that, in the event of a theft when their lock was being used, would replace not just the lock but the stolen bicycle (up to a certain amount) as well. Could a similar warranty work for select electronic parts?
I'm sure there are other potential solutions, but I don't really know this business very well. Anyway, that's Mr Minix's job! All I do know for sure is that the current model doesn't work very well for consumers like me.
Attachments
That is what the military do. You do get a complete audit trail and fully tested parts but is it worth the cost for what we do?, most likely not.
For example
N2369A JANTX2N2369A Military Transistor
Price: $22.20
Quantity in Basket: None
430 available for immediate delivery
Product code: T452PD
Volume Pricing
Quantity Price Each
1-9 $22.20
10-99 $20.20
100+ $18.20
Quantity:
View shipping costs
Military Transistors
NPN
TO-18 Package
Gold Plated Leads
Maximum Ratings:
Power Dissipation @ TA=25°C: 360mW
Power Dissipation @ TC=25°C: 1.2W
Collector-Base Voltage: 40V
Collector-Emitter Voltage: 15V
Emitter-Base Voltage: 4.5V
Operating & Storage Temperature: -65°C to 200°C
Specs:
DC Current Gain @ IC=10mA: 40 min ; 120 max
Output Capacitance: 4.0pF
Turn-on time: 12ns
turn-off time: 18ns
Manufactured by: Raytheon
Part Number: JANTX2369A
or
2N3716 JANTX2N3716 4A 80V Military Transistor
Price: $225.75
Quantity in Basket: None
7 available for immediate delivery
Product code: T458PD
Quantity:
View shipping costs
Knowing what I do now, I would pay $20 each for a matched, guaranteed pair of critical drivers or a diff. pair. However, $225 is a little steep (though now I know where that $350 military toilet seat in the 80's came from!). 
A full audit trail seems a bit much. Maybe there's a middle ground?
A full audit trail seems a bit much. Maybe there's a middle ground?
Interesting thread
This is quite interesting. A couple of you know I bought a Heathkit IT-18 beta tester and finally got it working.
Cutting to the chase, I have several Sanyo 2SD1047 transistors that I purchased from two sources, MCM and BDent. I purchased these sets last Fall and going back through them, the ones from MCM have a different silkscreen and measure below the specs on the datasheet. Specs say 100 to 200, they measure around 50. The BDent units I got in the fall measure around 120, so within spec.
But I just bought a dozen more from BDent. They look like the real mccoy, but they all measure around 65. What gives?
This is quite interesting. A couple of you know I bought a Heathkit IT-18 beta tester and finally got it working.
Cutting to the chase, I have several Sanyo 2SD1047 transistors that I purchased from two sources, MCM and BDent. I purchased these sets last Fall and going back through them, the ones from MCM have a different silkscreen and measure below the specs on the datasheet. Specs say 100 to 200, they measure around 50. The BDent units I got in the fall measure around 120, so within spec.
But I just bought a dozen more from BDent. They look like the real mccoy, but they all measure around 65. What gives?
This is quite interesting. A couple of you know I bought a Heathkit IT-18 beta tester and finally got it working.
Cutting to the chase, I have several Sanyo 2SD1047 transistors that I purchased from two sources, MCM and BDent. I purchased these sets last Fall and going back through them, the ones from MCM have a different silkscreen and measure below the specs on the datasheet. Specs say 100 to 200, they measure around 50. The BDent units I got in the fall measure around 120, so within spec.
But I just bought a dozen more from BDent. They look like the real mccoy, but they all measure around 65. What gives?
Is there any letters after the part number?
Whoops, sorry Davada. I left out one little piece of critical info. I bought all 'E' grades for hfe, which is 100 to 200. Some of the ones I have are measuring more like 'D' grades, which is 60 to 120.
For example, from my fall purchase, here is the coding on the trannies:
BDent - E 0C3
MCM - E 8J4
I know in email with BDent, they specify these are Sanyos.
For example, from my fall purchase, here is the coding on the trannies:
BDent - E 0C3
MCM - E 8J4
I know in email with BDent, they specify these are Sanyos.
Here is what is currently listed on MCMs site:
SANYO TRANSISTOR TO-3PB 160V 12A 100W BCE Transistor, Polarity: SI-N, Voltage: 160 V, Current: 12 A, Power: 100 W, Frequency: 15 MHz
I'm pretty positive at the time I was looking for Sanyo and not an alternative manufacturer, since these were slated for replacement in my Adcom 535 amp
SANYO TRANSISTOR TO-3PB 160V 12A 100W BCE Transistor, Polarity: SI-N, Voltage: 160 V, Current: 12 A, Power: 100 W, Frequency: 15 MHz
I'm pretty positive at the time I was looking for Sanyo and not an alternative manufacturer, since these were slated for replacement in my Adcom 535 amp
Hi Mr. Minix,
Please allow me to support your statements.
Your only option here is to buy from known 'safe" sources. This will cost more of course, but there are times when you simply can't be the least expensive vendor on the block. You can add value to your services.
There was a point in time when I was using over $80K a year in assorted parts. I had maybe 1 bad transistor in a couple years, and similar counts with ICs. My experience had taught me to buy from legit sources only. Parts from sources I didn't care to use had astronomically high defect rates, so there you go. It also helped that I tested all parts before I installed them - saved a lot of grief.
Look at it this way. If you buy directly from On Semi, or a distribution partner, they can be trusted as being a clean source. If your buyer elects to buy these same part numbers from another source without a chain of custody to the manufacturer, you have also assumed the role of insuring the quality for your customer. That is part of the decision to buy from other sources. An intangible. If you check the parts upon receipt, you have an opportunity to recoup your funds and return them, otherwise those parts are yours. The only way to recoup your money is to flush them out to unsuspecting buyers. That's really not cricket you know.
If your company is not willing to take on the role of incoming QC spot checks, then you can not afford to buy parts anywhere but the new part supply chain. It is as simple as that. I know, you didn't want to hear that said.
Purchasing discontinued part numbers is a high risk activity these days. It can be done with reduced risk as long as you choose your sources carefully and also do spot checks. I'm thinking transistors here. ICs are too complicated to check fully. A visual inspection against a knowledge of past appearance, case style and printing / logo. That will catch many right off.
I'm not trying to be hard on you at all. Just suggesting what I'd consider to be good business practices.
-Chris
Please allow me to support your statements.
Yes, absolutely correct.
Your only option here is to buy from known 'safe" sources. This will cost more of course, but there are times when you simply can't be the least expensive vendor on the block. You can add value to your services.
There was a point in time when I was using over $80K a year in assorted parts. I had maybe 1 bad transistor in a couple years, and similar counts with ICs. My experience had taught me to buy from legit sources only. Parts from sources I didn't care to use had astronomically high defect rates, so there you go. It also helped that I tested all parts before I installed them - saved a lot of grief.
What can I say? That's a perfectly reasonable request and the route that will generally make the consumer happier.
That's true on the face of things. However, I think it should be possible to spot check a few parts in-house. Your company should be checking during the receiving process, and you should have at least one real technician on staff who can check some of these things. Incoming quality assurance is something you can't really afford to be without these days.
I'm really sorry to hear this. If you read back some, I specifically pointed this trend as being responsible for the current pollution in the parts inventory. To be perfectly honest with you, you really can't afford to not do some kind of incoming inspection on parts procured outside the normal distribution channels. The one and only way you can save your reputation will be to stop those bad parts from exiting the building.
Look at it this way. If you buy directly from On Semi, or a distribution partner, they can be trusted as being a clean source. If your buyer elects to buy these same part numbers from another source without a chain of custody to the manufacturer, you have also assumed the role of insuring the quality for your customer. That is part of the decision to buy from other sources. An intangible. If you check the parts upon receipt, you have an opportunity to recoup your funds and return them, otherwise those parts are yours. The only way to recoup your money is to flush them out to unsuspecting buyers. That's really not cricket you know.
If your company is not willing to take on the role of incoming QC spot checks, then you can not afford to buy parts anywhere but the new part supply chain. It is as simple as that. I know, you didn't want to hear that said.
Your buyer(s) should already know what level of quality they are getting from each supplier. It's their job and profession for crying out loud. If your staff in this department, it's high time to pick up a seasoned professional with a good track record. He's the guy who can mentor the other people in that department. He may cost you more for salary, but what he can save you would pay his salary I bet. That's the person who will create a smooth running department and also knows how and where to second source parts. His own industry contacts will add value as well.
Purchasing discontinued part numbers is a high risk activity these days. It can be done with reduced risk as long as you choose your sources carefully and also do spot checks. I'm thinking transistors here. ICs are too complicated to check fully. A visual inspection against a knowledge of past appearance, case style and printing / logo. That will catch many right off.
I'm not trying to be hard on you at all. Just suggesting what I'd consider to be good business practices.
Yes, and that's why I'm a little surprised that you're not taking at least some minimal steps to protect your product, I am not suggesting a buying spree of new Agilent and Tektronix equipment in a lab. A smart guy and some basic equipment is what you need.
Well, yes. It's the only way to get those parts beyond buying old factory stock. That is not the problem though, it's forgetting to do the other half of the job (like checking these parts).
I am extremely pleased that you are. Please take my comments as constructive in nature.
-Chris
Hi Fred,
People are cheap most commonly. They will buy from the least expensive source. Just have a look at the audio industry if you need any proof.
Hi sonidos,
-Chris
This is normally not the case.
Yes. If not, the natural reaction would be to avoid this vendor. This is what the majority of people will do, rather than attempt to contact the place they bought them from.
Well, sadly they will not. Not even commercial customers will do this.
People are cheap most commonly. They will buy from the least expensive source. Just have a look at the audio industry if you need any proof.
Well, it's actually a bad business model for any customer. Never sell low or poor quality goods when they are advertised as high quality. A bad reputation is difficult to rebuild, it's easy to start fresh than to crawl back out of a very deep hole.
Hi sonidos,
There are those pesky gain range markings as you've been talking about. Then there is the situation where sources of these parts are drying up. Bdent may have bought from the same place that MCM did earlier in time. It would be rare for a part to fail to live up to it's data sheet. I must say that I'm a little concerned and suspicious of those parts.
-Chris
Chris,
I asked BDent and they said they buy factory direct from Sanyo. I was pretty happy at first because I bought a dozen of the 2SB817 too, which is the PNP power transistor. These were just great....all measuring from 145 to 160. So I really got deflated when I started measuring the NPNs.
What is weird is that the NPNs I bought in the fall should make a decent match with the PNPs I just got for the Adcom. But still, this is really disappointing.
I asked BDent and they said they buy factory direct from Sanyo. I was pretty happy at first because I bought a dozen of the 2SB817 too, which is the PNP power transistor. These were just great....all measuring from 145 to 160. So I really got deflated when I started measuring the NPNs.
What is weird is that the NPNs I bought in the fall should make a decent match with the PNPs I just got for the Adcom. But still, this is really disappointing.
ah, i once ordered 10x Sanken 2sc4883a for my amp project, and after i asked if they are really from sanken, i got assured they sell no fake stuff (dutch company). i only tested Hfe and they all are matched pretty well even, and further my sometimes paranoid mind can not find any clues as to them being fake. (not a type liable to be faked even)
em but: companies, managers (accountants): do not save on money! get high grade stuff and invest in skills
em but: companies, managers (accountants): do not save on money! get high grade stuff and invest in skills
This is quite interesting. A couple of you know I bought a Heathkit IT-18 beta tester and finally got it working.
Cutting to the chase, I have several Sanyo 2SD1047 transistors that I purchased from two sources, MCM and BDent. I purchased these sets last Fall and going back through them, the ones from MCM have a different silkscreen and measure below the specs on the datasheet. Specs say 100 to 200, they measure around 50. The BDent units I got in the fall measure around 120, so within spec.
But I just bought a dozen more from BDent. They look like the real mccoy, but they all measure around 65. What gives?
If you could show a pic of them I could identify the fake from it.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.