Bad New Components?

[R.G.]

I just had a weird one. A fellow bought one of my PCBs to rebuild a Vox amp and wound up having a non-functioning reverb. We did some email back and forth with voltages and tests that will be very familiar to the people who have asked for fixit help her, and we found that one of his brand-new 2N5088 transistors was shorted base to emitter. He's a skilled solderer, so he didn't kill it.

I always rant and rave about not blaming the part for being faulty, about it being soldering, wiring or pinout problems, but sometimes it does happen.

This failure was remarkable to me because it's the first time I have found a real, true, no-fooling bad-when-new transistor since the middle 1980s.   

That puts it firmly into the category of the exception that proves (in the sense of "tests") the rule.

The race is not always to the swift, nor the contest to the strong - but that's the way to bet. 

This post brought to you by R.G.'s truth in blather policy.

[GiovannyS10]

Yes man, we think no but it can happen.  Not with me, but a friend already said me he was bought a new shorted transistor. And last week i trying to build a distortion and don't worked. I checked the layout 5 or 6 times and all right. On the end i rebuild it using other germanium diodes. Worked right. I think the problem was one of my new GE diodes.

We need to be attempt to not trow on trash good projects thinking its was own problem. The components can come shorted too.

Nice post! 

[midwayfair]

Someone's never ordered static sensitive parts from certain budget suppliers in recent years ...

[Mark Hammer]

One of the largely invisible aspects of production costs (at least to customers) is quality control.  The cost of parts not only reflects the materials and processes used to make them, but the labor and equipment costs of checking that the product is what you intended and claimed to make.  The customer buys not JUST your materials and fabrication process, but your assurance that the product IS the product.

I can't imagine that any manufacturer who sinks big money into production facilities and equipment doesn't care about quality control, since that's a pretty big and expensive gamble.  But I CAN imagine that a manufacturer might cross their fingers and cut back a bit on labor costs for quality control, as one of the cut-able corners.  I don't like to think it, but I can imagine it.

[analogguru]

Times when every single transistor was tested for specs are long gone - too expensive today.

It has been replaced by the so called "AQL-rate" (Acceptance Quality Limit):
https://qualityinspection.org/what-is-the-aql/

At the end of a production day a sample batch is taken and tested for the AQL-rate.  If the failure rate exceeds the limit the complete production run of the day will be dumped.  If it is within the set limit it will be sold - even if there could be a faulty part hidden between the good ones.

[bloxstompboxes]

I work in a primarily SMD production environment. Usually, the faulty parts I run accross are ICs. Trannies are 99.9% ok. The more complicated, or harder to rework a component is, the more likely it is at fault. Seems to be the nature of the game in my experience. Most of the issues I see are lifted leads, tombstoned, billboarded, or missing components altogether. I can't remember the last time I came accross a  bad trannie, resistor, cap, or inductor. Usually, if one of them is bad, it is due to it being cracked or damaged due to poor board handling.

[R.G.]

With all the different views mixed in, I want to be overly clear to beginners reading this:
===================================================

Your problems with a build are [still] almost certainly not a bad new component.

===================================================
This was the first one I've found in some decades, and I use a lot of components.
I just needed to point out that it's only extremely rare, not impossible.   

[disorder]

You know when you've been troubleshooting a while and eventually you say out loud "WELL I KNOW IT CAN'T BE THIS"... It's always good to remember that once in a blue moon, THAT will in fact end up being the cause of your issues.

I should also add I work in FA in a production setting for an audio company. Our products are very digital now and we use a lot of complex SMD IC and I see those fail everyday straight from the vendor. Almost always we can narrow them down to strict batches or date codes and can tell when the materials or methods at the fab plant started to drift. And yet, in nearly 10 years of DIY at home I have never seen it happen even when I moved over to SMD stuff.

[bloxstompboxes]

I should also add I work in FA in a production setting for an audio company. Our products are very digital now and we use a lot of complex SMD IC and I see those fail everyday straight from the vendor. Almost always we can narrow them down to strict batches or date codes and can tell when the materials or methods at the fab plant started to drift. And yet, in nearly 10 years of DIY at home I have never seen it happen even when I moved over to SMD stuff.

That's because at home, we never deal with the volumes we do at work.

[pinkjimiphoton]

With all the different views mixed in, I want to be overly clear to beginners reading this:
===================================================

Your problems with a build are [still] almost certainly not a bad new component.

===================================================
This was the first one I've found in some decades, and I use a lot of components.
I just needed to point out that it's only extremely rare, not impossible.   

love ya RG, you are the resident guru, but i have to humbly disagree.

i have had a LOT of things fail with brand new components the last few years... in particular, resistors. so far every thing i have built that didn't work has led back to what i call "internally decapitated" components, particularly tayda resistors. they seem to be solid, but on one side the lead is open, and often broken inside. this can lead to hours of debugging and replacing other stuff and nad scratching and choice words only electricians usually seem to know.

so...two things i've learned... check the components before installing.... only takes a couple seconds to prevent hours of trying to figure stuff out, and never ever EVER us solid conductor wire for anything that MAY ever be flexed.

have also encountered a lot of "bad" nte electros the last year or so...i agree with analog guru, QC is a thing of the past.

no issues with any transistors... yet. def not trying to be arguementative, but with newbs, which i still consider myself to be all these years later, a lot of times folks don't realize how easy it is to break a "standy uppy" resistor, or for solid core wire to break somewhere inside the coating.

thanks for the honesty sir. as always, you rock man.

[Jay]

Years ago at work we had contorl line telephone exchange custom built.  50V, all discrete components.  Didn't work.

After a lot of headscratching, pulling apart, measuring we found that the diodes were faulty. All of them - dozens and dozens.  Faulty in the sense that the band had been printed on the wrong end so they were all intalled the wrong way round!

[greaser_au]

Batch quality assurance is not a new thing.... At the factory I was seconded to QA for batch testing incoming assemblies from subcontractors over 30 years ago. The batch acceptance quantities were well defined even back then.

"Internally decapitated" components...  if the many assembly/building videos I've seen on youtube are any measure, the internal decapitation occurs at project assembly, not the factory. It is a pet hate of mine to see someone bending a component lead with all the stress being placed on the component body. The forming tool (pliers/bender) MUST always be used between the component body and the bend - that is:  hold the lead with the pliers next to the body and make the bend on the other side of the pliers with your fingers.  Most I have seen bend the lead with the pliers on the free end of the lead,  with the body side of the lead unsupported, a good recipe for component failure, either at assembly, or further down the track.

david

[pinkjimiphoton]

that's how i always do it dave.
in the bad batches i've gotten, i've taken them right off the string and found bad ones, no bending necessary.
that said, vertically installed resistors will do that pretty easily.
peace!

[greaser_au]

Jimi,

It's interesting (but very sad) that there are dead ones are coming off the bandolier...     I suppose the failure rate is reflected in the price... (BTW I happily use these!)

As for vertical mounted resistors,  it is good practice to keep the body end off the board by 1.5mm or  1/16". If the body is down hard against that board,  it will lever the lead out of the body with any amount of sideways pressure, the downside is that any downward pressure will push the pad off the board.   It was common to see the resistors being supplied with a kink in the 'short' lead to hold the body clear of the PCB  (and often the body paint extended down over the kink).

david

[Ice-9]

Hi Guys,
I built a simple booster and every component was faulty from new........ Only joking

Although I can say for many years I have not come across a faulty component, a couple of weeks ago I did have a suspected damaged DSP IC, so after checking all my anti static building area and tools for any problems I then have been talking with a person involved with the manufacturer of the DSP, still working through if damage was caused on my side or if any manufacture process changes may have altered which could result in the problem I had. Most likely but unproved as yet is that the issue would be static damage.

[pinkjimiphoton]

Jimi,

It's interesting (but very sad) that there are dead ones are coming off the bandolier...     I suppose the failure rate is reflected in the price... (BTW I happily use these!)

As for vertical mounted resistors,  it is good practice to keep the body end off the board by 1.5mm or  1/16". If the body is down hard against that board,  it will lever the lead out of the body with any amount of sideways pressure, the downside is that any downward pressure will push the pad off the board.   It was common to see the resistors being supplied with a kink in the 'short' lead to hold the body clear of the PCB  (and often the body paint extended down over the kink).

david

i do something si,ilar now, i put a little loop at the top with some needle nose and make sure the lead on standing resisters has a bit of stress relief,  but i've still encountered it right off the reel, too. it could be from pulling them out i suppose, but i've never had that problem with other manufacturers. still use the cheap ones tho . nte prices are ridiculous

[garcho]

I just had my first experience with a batch of faulty components. I ordered 50 LM386 from an unknown supplier on eBay, just to use as a VCC/2 (Vref) source. They were super cheap. 
The voltages were all over the place and all over the whole pinout, each one messed up, big time, in a different way. There wasn't one decent IC in all 50. I assumed I was measuring wrong, changed power supplies, breadboards, etc., until eventually I found one old 386, a TI from a previous Mouser order. 4.5V on the money. I rarely buy the cheap eBay crap, because I've learned my lesson years ago. So, I guess that means, shame on me.

[bloxstompboxes]

I just had my first experience with a batch of faulty components. I ordered 50 LM386 from an unknown supplier on eBay, just to use as a VCC/2 (Vref) source. They were super cheap. 
The voltages were all over the place and all over the whole pinout, each one messed up, big time, in a different way. There wasn't one decent IC in all 50. I assumed I was measuring wrong, changed power supplies, breadboards, etc., until eventually I found one old 386, a TI from a previous Mouser order. 4.5V on the money. I rarely buy the cheap eBay crap, because I've learned my lesson years ago. So, I guess that means, shame on me.

Tell me they weren't from e-vanc74 and cost $2.27. I bought mine in DEC and haven't used them yet. I was a little pissed since they were just tossed in a padded envelope. Surprisingly, only 2 of them had bent leads. But,either way, what should I expect for so low a price?

[wavley]

Years ago at work we had contorl line telephone exchange custom built.  50V, all discrete components.  Didn't work.

After a lot of headscratching, pulling apart, measuring we found that the diodes were faulty. All of them - dozens and dozens.  Faulty in the sense that the band had been printed on the wrong end so they were all intalled the wrong way round!

I recently (within the last couple of years) had that very thing happen when prototyping something at work.  A batch of SMD Zeners with the band on the wrong side, flipped them around and everything was great.