On Sat, 16 Dec 2017 03:01:23 GMT, Steve Wilson <no@spam.com> wrote:>John Larkin <jjlarkin@highland_snip_technology.com> wrote: > >> On Sat, 16 Dec 2017 00:37:35 GMT, Steve Wilson <no@spam.com> wrote: > >>>It seems you are taking a lot for granted. I'm not so trusting. > >> If you divert your energy into sidetracks like this, you won't >> survive. Put your energy into designing and selling and supporting >> products. In the very rare case that you have a part problem, fix it. > >I am planning on fixing it before there is a problem. > >> We trust a bunch of suppliers to do things right. *They* test every >> part. > >How? You are telling me they take each part out of the reel and test it? To >what tolerance? And then they put each part back? And put the top tape back >on?Don't be silly. They make the parts, trim/bin/test them, and then they put them on the reel.> >Maybe the manufacturers do that before they put the part in the reel. But >they don't give you any information on the distribution. They don't tell >you what their test limits are.The guaranteed limits are on the data sheet. Sometimes they include histograms.> >> Really, we are professionals, building and shipping in volume. Our >> field reliability is superb. We get awards. I don't think you have >> standing to lecture us on this. > >You are a very small company and have got away with things like this since >the beginning. Very few large companies could afford to operate this way.We sell a million dollars in a good month. We sell to the biggest aerospace and semiconductor companies on the planet. Our stuff is way better than the things they make themselves.> >I have grown companies from nothing to multimillion dollar business twice. >I am planning on doing it again.Burning holes in tape packaging to test resistors and caps is not an efficient way to do that.> >But setting up a business takes a lot of planning. I'm hoping to prevent a >lot of mistakes I made before. Incoming inspection was a big one. I don't >think it would take as much as you seem to believe to do a proper job.Parts are amazingly reliable these days, orders of magnitude better than the nasty old days of early 74xx plastic chips. If you test millions of resistors and caps you'll probably never find one out of tolerance, much less DOA. Really. [1]> >And that's only one of dozens of details I need to take care of.Skip that one; it's a waste of time. [1] well, excepting NTC capacitors. Tempcos are all over the place, but at least the same in a reel. PCBs are probably the worst things that we buy. -- John Larkin Highland Technology, Inc lunatic fringe electronics
Low MOSFET IDSS current
Started by ●December 9, 2017
Reply by ●December 16, 20172017-12-16
Reply by ●December 16, 20172017-12-16
pcdhobbs@gmail.com wrote:>>>>> An *authorized distributor* sent you 16-pin DIPs marked '74HC7474'? >>>>> Do tell.>>>>This was before your time. Things were a bit looser then. >>> I've been in the biz longer than HCMOS has been around. Thanks for >>> playing though.>>Yes, but that was at IBM.> Nope, long before that, and the whole issue is irrelevant to your *ahem* > misremembering the 74HC7474 thing and then doubling down when > challenged.> Steve, if you have anything specific to back up your contentions about > the alleged misbehaviour of top-shelf distributors, I'd genuinely be > glad to hear about it, because I depend on them. If not, you really > should just fold your tent on this one.As I said, it was a long time ago. Back in the 80's. There was no ebay. The only surplus vendor was Holtek. They had some interesting stuff, but we didn't buy much from them. The only other place to buy semiconductors and components was national distributors. They screwed us royally sending us junk. Things were very much different then. Pretty much absolute chaos as far as parts quality goes. We spent a lot of time trying to recover from bad shipments. Nowadays, you probably don't have to worry about getting too many bad parts from modern vendors. So stop worrying.> Cheers> Phil Hobbs
Reply by ●December 16, 20172017-12-16
John Larkin <jjlarkin@highlandtechnology.com> wrote:> On Sat, 16 Dec 2017 03:01:23 GMT, Steve Wilson <no@spam.com> wrote:>>And that's only one of dozens of details I need to take care of.> Skip that one; it's a waste of time.The more I think of it, a better place to do the test is at the pick and place, just before the component is placed on the pcb. Then I will get a record of the value of each component and the location. It would take only a bit of software to convert the location to a reference designation. An earlier poster mentioned another machine that does this, but he didn't know if they actually measured the value.
Reply by ●December 16, 20172017-12-16
Steve Wilson <no@spam.com> wrote:> pcdhobbs@gmail.com wrote: > >>>>>> An *authorized distributor* sent you 16-pin DIPs marked '74HC7474'? >>>>>> Do tell.> As I said, it was a long time ago. Back in the 80's. There was no ebay. > The only surplus vendor was Holtek. They had some interesting stuff, but > we didn't buy much from them.Make that Halted http://halted.com/ Halted was a fun place to visit. Junk piled everywhere on the floor. Then they moved into fancy digs with everything organized on tables so it wasn't as interesting. So I stopped going. Also, I got the part wrong. It was a plain 7474. We didn't use 74HC anywhere in the company at the time.
Reply by ●December 16, 20172017-12-16
On Sat, 16 Dec 2017 13:10:53 GMT, Steve Wilson <no@spam.com> wrote:>Steve Wilson <no@spam.com> wrote: > >> pcdhobbs@gmail.com wrote: >> >>>>>>> An *authorized distributor* sent you 16-pin DIPs marked '74HC7474'? >>>>>>> Do tell. > >> As I said, it was a long time ago. Back in the 80's. There was no ebay. >> The only surplus vendor was Holtek. They had some interesting stuff, but >> we didn't buy much from them. > >Make that Halted > >http://halted.com/Anyone who would even think of buying production components from a junk dealer deserves what they get. They sell floor sweepings, and anything else that looks like a part. Did you buy production hardware from PolyPacks and RadioShack, too? <yeesh!>> >Halted was a fun place to visit. Junk piled everywhere on the floor. Then >they moved into fancy digs with everything organized on tables so it wasn't >as interesting. So I stopped going. > >Also, I got the part wrong. It was a plain 7474. We didn't use 74HC anywhere >in the company at the time.So it was marked "747474"? This is getting ridiculous.
Reply by ●December 16, 20172017-12-16
On Sat, 16 Dec 2017 13:04:42 GMT, Steve Wilson <no@spam.com> wrote:>John Larkin <jjlarkin@highlandtechnology.com> wrote: > >> On Sat, 16 Dec 2017 03:01:23 GMT, Steve Wilson <no@spam.com> wrote: > >>>And that's only one of dozens of details I need to take care of. > >> Skip that one; it's a waste of time. > >The more I think of it, a better place to do the test is at the pick and >place, just before the component is placed on the pcb. Then I will get a >record of the value of each component and the location. It would take only a >bit of software to convert the location to a reference designation.And a machine that can test every component. ...and the money to pay for such a machine and time it adds to production. And if the reel is bad, you shut down production until you can get more parts? Sure sounds like a great idea! <good grief!>> >An earlier poster mentioned another machine that does this, but he didn't >know if they actually measured the value.
Reply by ●December 16, 20172017-12-16
On Sat, 16 Dec 2017 13:04:42 GMT, Steve Wilson <no@spam.com> wrote:>John Larkin <jjlarkin@highlandtechnology.com> wrote: > >> On Sat, 16 Dec 2017 03:01:23 GMT, Steve Wilson <no@spam.com> wrote: > >>>And that's only one of dozens of details I need to take care of. > >> Skip that one; it's a waste of time. > >The more I think of it, a better place to do the test is at the pick and >place, just before the component is placed on the pcb. Then I will get a >record of the value of each component and the location. It would take only a >bit of software to convert the location to a reference designation. > >An earlier poster mentioned another machine that does this, but he didn't >know if they actually measured the value.Our Universal machine does optical inspection, not electrical, on every part. The more real problem isn't DOAs, it's parts damaged in process, or by electrical abuse. Lead-free temperature profiles are bad, as is water washing (for some parts) or solvent wash (for others). We've recently had problems with presumably sealed relays. The conclusion: never get them near water. We ran a couple of these boards https://www.dropbox.com/s/2avvklzwtzc8rz4/P951_E1.JPG?raw=1 (and then threw them away) through various soldering and cleaning cycles. We have setups that can measure contact resistance and leakage on almost every contact on the board. -- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by ●December 16, 20172017-12-16
On Sat, 16 Dec 2017 13:10:53 GMT, Steve Wilson <no@spam.com> wrote:>Steve Wilson <no@spam.com> wrote: > >> pcdhobbs@gmail.com wrote: >> >>>>>>> An *authorized distributor* sent you 16-pin DIPs marked '74HC7474'? >>>>>>> Do tell. > >> As I said, it was a long time ago. Back in the 80's. There was no ebay. >> The only surplus vendor was Holtek. They had some interesting stuff, but >> we didn't buy much from them. > >Make that Halted > >http://halted.com/ > >Halted was a fun place to visit. Junk piled everywhere on the floor. Then >they moved into fancy digs with everything organized on tables so it wasn't >as interesting. So I stopped going. > >Also, I got the part wrong. It was a plain 7474. We didn't use 74HC anywhere >in the company at the time.There was Halted and Haltek. That always confused me. There was even an electronic surplus place on Market Street in San Francisco. The real estate boom killed most of them. -- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by ●December 16, 20172017-12-16
On Sat, 16 Dec 2017 09:19:16 -0500, krw@notreal.com wrote:>On Sat, 16 Dec 2017 13:10:53 GMT, Steve Wilson <no@spam.com> wrote: > >>Steve Wilson <no@spam.com> wrote: >> >>> pcdhobbs@gmail.com wrote: >>> >>>>>>>> An *authorized distributor* sent you 16-pin DIPs marked '74HC7474'? >>>>>>>> Do tell. >> >>> As I said, it was a long time ago. Back in the 80's. There was no ebay. >>> The only surplus vendor was Holtek. They had some interesting stuff, but >>> we didn't buy much from them. >> >>Make that Halted >> >>http://halted.com/ > >Anyone who would even think of buying production components from a >junk dealer deserves what they get. They sell floor sweepings, and >anything else that looks like a part. Did you buy production hardware >from PolyPacks and RadioShack, too? <yeesh!> >> >>Halted was a fun place to visit. Junk piled everywhere on the floor. Then >>they moved into fancy digs with everything organized on tables so it wasn't >>as interesting. So I stopped going. >> >>Also, I got the part wrong. It was a plain 7474. We didn't use 74HC anywhere >>in the company at the time. > >So it was marked "747474"? This is getting ridiculous.The surplus houses were good for test equipment, cables, hardware, weird stuff for engineering and prototypes, not parts for production. I got started in picosecond electronics with flea market and junk store equipment and parts, when I was living on unemployment. I also bought broken microwave and fast-pulse gear to take apart and study. All this was under $200: https://www.dropbox.com/s/mvq9f52bswroqz6/1S2-547.jpg?raw=1 The Foothill Flea Market was great. Kids would empty their dad's garage into a pickup and haul it there to get rid of. Lots of old HP stuff. https://www.dropbox.com/s/sweqdp925irzvgy/training0.jpg?raw=1 There was a set of girlie-nudie HP postcards that the sales people gave away; I should have bought them. -- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by ●December 16, 20172017-12-16
John Larkin <jjlarkin@highlandtechnology.com> wrote:> The more real problem isn't DOAs, it's parts damaged in process, or by > electrical abuse.This is very alarming. I'm thinking of ordinary components - resistors, capacitors, diodes, maybe inductors. Do any of these show up bad in your testing? If so, how do you know where the parts were damaged? What are the symptoms - out of tolerance, open, shorted, etc? How many other bad parts are on the board that didn't get detected? How can pick and place damage a part?
