pucho812
Well-known member
why is it manufactures insist on using underrated(low temp) electrolytics... does it really save that much money in the long run? 
cheap capacitors
- Thread starter pucho812
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owel
Well-known member
I guess if you're building hundreds of thousands or millions of unit. And if the part won't see high temp, why specify it?
exactly.owel said:
Add to that, its better to use the same part mulitple times in your systems (even if they are only just good enough) than to specify multiple different parts.
/R
pucho812
Well-known member
I understand both statements. but wouldn't it make sense to plan for worst case scenario? what's a few extra cents on the dollar? well in this economy maybe it's everything...
also maybe under normal conditions it's not an issue...
also maybe under normal conditions it's not an issue...
okgb
Well-known member
Well , you know it's well proven
some Countries [ companies ] WILL
go to great lengths to save a dime
some Countries [ companies ] WILL
go to great lengths to save a dime
sahib
Well-known member
pucho812 said:
Few extra cents x say 50 capacitors on each unit x 10,000 or 20,000 units adds up to a lot of bucks. If you have, say a modest 10 different product in your range then bucks rises even more.
In terms of reliability, no manufacturer designs (or get designed) anything beyond the warranty period, unless they give life time warranty. Every drop of juice is squeezed out of the design until no more savings can be made. For example the great majority of hi-fi amplifiers will never be used at maximum power, so the power transformers are generally under specified or right on the edge and no more. Power supply stages are worse. That is why the PCBs around the rectifiers are always baked.
There is something called the returns ratio, particularly in consumer electronics, the percentage of the batch which will fail before the warranty period and returned. This is built within the overall costs. This is one of the reasons why they don't repair returned products anymore (the other being the surface mount hence low cost). Whereas in the very old days they used to. If your amp failed the retailer would send it back to the manufacturer for a repair. In fact it is not in really very old days. I remember in 1986 a friend of mine had a new hi-fi set and the power amp transformer started buzzing. They told him it would take four to six weeks for the repair. I added neoprene washers to the fixing screws and it was all up and running in half an hour.
All economy I am afraid.
livingnote
Well-known member
http://www.youtube.com/watch?v=1_rD1LeECDE
Quality Management is the first thing that puzzled me when my economist friend started talking
shop. I always thought they were increasing quality and making sure it's good every time, turns
out QMS is all about reducing quality until you hit the line.
You assume a fictitious customer who has a target of 5 years and you build a unit that generally
lasts about that long, then you have fulfilled the "Customer Satisfaction Guarantee" and so are:
"Top Quality conforming to International Standards." (Which the marketing departments then
of course babel into "We sell something good")
It's amazing how you can make prices drop when going turnkey commercial - say, if you have a
relay card and one of the 60 relays drops out (the ones us types pay 3.50-5€ for, right?), it's
cheaper to replace the entire card than to actually diagnose it and then resolder one relay.
Like - you can get your card for 29.90€, with 60 relays, resitors, caps, headers, the whole smash,
PCB double-sided, HAL, soldermask'ed, and all robo-assembled. And looks totally sexy...to begin with...
Quality Management is the first thing that puzzled me when my economist friend started talking
shop. I always thought they were increasing quality and making sure it's good every time, turns
out QMS is all about reducing quality until you hit the line.
You assume a fictitious customer who has a target of 5 years and you build a unit that generally
lasts about that long, then you have fulfilled the "Customer Satisfaction Guarantee" and so are:
"Top Quality conforming to International Standards." (Which the marketing departments then
of course babel into "We sell something good")
It's amazing how you can make prices drop when going turnkey commercial - say, if you have a
relay card and one of the 60 relays drops out (the ones us types pay 3.50-5€ for, right?), it's
cheaper to replace the entire card than to actually diagnose it and then resolder one relay.
Like - you can get your card for 29.90€, with 60 relays, resitors, caps, headers, the whole smash,
PCB double-sided, HAL, soldermask'ed, and all robo-assembled. And looks totally sexy...to begin with...
+1
We had a Drawmer MX60 channel strip in the studio some few years back. I don't know what the cool kids think of those boxes, but we didn't have much gear (or cash) at the time, and we liked it a lot.
Over time (3 or 4 years) we began to like it less and less, and after some time I popped the lid and many of the 'lytics had bulged up and leaked, including all the output caps. Sadly the melty multi-layer PCB and skinny copper traces don't like being desoldered at all - what a mess! Cheap = expensive!
I'd expected more from Drawmer - I accept that it was their lower end stuff, but customers move up and it leaves a bad taste.
In an ideal world, if we are to expect parts to have a finite life, then it would be nice if they were 'service' parts, and engineered accordingly - i.e. replaceable by an OK tech with OK gear. It's one of the reasons I like older gear.
We had a Drawmer MX60 channel strip in the studio some few years back. I don't know what the cool kids think of those boxes, but we didn't have much gear (or cash) at the time, and we liked it a lot.
Over time (3 or 4 years) we began to like it less and less, and after some time I popped the lid and many of the 'lytics had bulged up and leaked, including all the output caps. Sadly the melty multi-layer PCB and skinny copper traces don't like being desoldered at all - what a mess! Cheap = expensive!
I'd expected more from Drawmer - I accept that it was their lower end stuff, but customers move up and it leaves a bad taste.
In an ideal world, if we are to expect parts to have a finite life, then it would be nice if they were 'service' parts, and engineered accordingly - i.e. replaceable by an OK tech with OK gear. It's one of the reasons I like older gear.
pucho812
Well-known member
It's just annoying. I pulled apart several digital reverb and delay units at work today all that were not functioning properly. All had similar problems of blow electrolytics in the psu. All were purchased new and are less then a year old... Should not have to recap a unit after less them 6 months in service of normal conditions.
i popped open a manley or summit unit a few years back (can't remember which)
and was suprised to see so many bulging 85 degree caps in such a nice and
well respected tube unit.
shit not lasting long is not a way to build a stellar reputation.
i guess if it sounds great for the first few years, it's all good?
and was suprised to see so many bulging 85 degree caps in such a nice and
well respected tube unit.
shit not lasting long is not a way to build a stellar reputation.
i guess if it sounds great for the first few years, it's all good?
Having been involved in exactly these type of decisions for a decent sized manufacturer I have a few comments.
Yes there are economies in using the same parts in multiple places rather than bringing in multiple parts. In practice this generally means parts being used that are better (more uF or higher voltage) than needed if unique parts were specified for every node.
Products are not designed to fall apart one day past warranty, the science isn't that precise. Generally there are only a handful of weak links in a given design that will dominate effective service life, and even then reliability engineering is a bit of a seat of the pants exercise, where there is a dynamic tension between engineering wanting to keep using old proven parts, and purchasing trying to save money by bringing in newer cheaper parts (after passing engineering imposed hurdles to prove they don't suck). In an ideal world these newer cheaper parts are also more reliable, and that has generally been my experience but there are always gotch'as and vendors who lose the recipe after making good parts for years.
Regarding sizing power transformers for audio amps, that could make a chapter in the book all by itself. In general these transformers are more taxed by UL testing parameter than in actual audio use, as it should be. Another quirk about audio amps that is becoming a distant memory as simple class AB fades into historical obscurity, is that FTC regulations required a long 1/3 power preconditioning cycle before power is measured. For those reading along at home, 1/3 power is the worst case for heat sink dissipation in simple class AB so a serious heat load. Another little known fact is transformers put out more power when cold than hot, because wire resistance actually increases with hear rise,,, long story short, the FTC rules forced amps to be over designed for actual use. Modern multi rail amps are dialed in to run relatively cool at 1/3 power mooting the FTC preconditioning test.
Another tidbit about transformers in audio application is that dynamic music does not make a well defined or consistent load. Also clip limiting and amp protection circuitry can reduce stress on the transformer vs an unprotected amp channel or theoretical calculations. I recall being told by a new engineer that the transformer being used in a new version of a popular 300W topbox mixer/amp was inadequate. Since we were shipping thousands of channels of month using this exact transformer and power amp, with near zero service complaints. There was nothing wrong with the young engineers math, but sometimes the real world is easier than the test bench not harder.
I recall when we decided we wanted to increase our warranty guarantee from 3 years to 5 years at my old day job. We did a thorough review of what our actual warranty experience really was model by model. We found we were already fine at 5 years, with the exception of one amp in my product mix that had a previously undiscovered design flaw. It was a low volume seller, so service didn't notice that the claims history was out of whack and flag it for engineering review, they generally respond to how big the stack of repairs is.
Curiously when I told the engineering director for the power amp division what parts were failing, he looked at the schematic and immediately found the mistake... a simple value change later and that amp was rock solid too.
I have been out of this high volume manufacturing mix for several years, and I would be apprehensive these days about offshore contract manufacturing where the contract manufacturer is allowed to source the parts and profit from saving money. Most of the chinese assembly contracts I dealt with, we specified every part.. But then was then,, I don't know how it goes now.
JR
Yes there are economies in using the same parts in multiple places rather than bringing in multiple parts. In practice this generally means parts being used that are better (more uF or higher voltage) than needed if unique parts were specified for every node.
Products are not designed to fall apart one day past warranty, the science isn't that precise. Generally there are only a handful of weak links in a given design that will dominate effective service life, and even then reliability engineering is a bit of a seat of the pants exercise, where there is a dynamic tension between engineering wanting to keep using old proven parts, and purchasing trying to save money by bringing in newer cheaper parts (after passing engineering imposed hurdles to prove they don't suck). In an ideal world these newer cheaper parts are also more reliable, and that has generally been my experience but there are always gotch'as and vendors who lose the recipe after making good parts for years.
Regarding sizing power transformers for audio amps, that could make a chapter in the book all by itself. In general these transformers are more taxed by UL testing parameter than in actual audio use, as it should be. Another quirk about audio amps that is becoming a distant memory as simple class AB fades into historical obscurity, is that FTC regulations required a long 1/3 power preconditioning cycle before power is measured. For those reading along at home, 1/3 power is the worst case for heat sink dissipation in simple class AB so a serious heat load. Another little known fact is transformers put out more power when cold than hot, because wire resistance actually increases with hear rise,,, long story short, the FTC rules forced amps to be over designed for actual use. Modern multi rail amps are dialed in to run relatively cool at 1/3 power mooting the FTC preconditioning test.
Another tidbit about transformers in audio application is that dynamic music does not make a well defined or consistent load. Also clip limiting and amp protection circuitry can reduce stress on the transformer vs an unprotected amp channel or theoretical calculations. I recall being told by a new engineer that the transformer being used in a new version of a popular 300W topbox mixer/amp was inadequate. Since we were shipping thousands of channels of month using this exact transformer and power amp, with near zero service complaints. There was nothing wrong with the young engineers math, but sometimes the real world is easier than the test bench not harder.
I recall when we decided we wanted to increase our warranty guarantee from 3 years to 5 years at my old day job. We did a thorough review of what our actual warranty experience really was model by model. We found we were already fine at 5 years, with the exception of one amp in my product mix that had a previously undiscovered design flaw. It was a low volume seller, so service didn't notice that the claims history was out of whack and flag it for engineering review, they generally respond to how big the stack of repairs is.
Curiously when I told the engineering director for the power amp division what parts were failing, he looked at the schematic and immediately found the mistake... a simple value change later and that amp was rock solid too.
I have been out of this high volume manufacturing mix for several years, and I would be apprehensive these days about offshore contract manufacturing where the contract manufacturer is allowed to source the parts and profit from saving money. Most of the chinese assembly contracts I dealt with, we specified every part.. But then was then,, I don't know how it goes now.
JR
livingnote
Well-known member
I remember repairing my Technics reciever, back then it was the "Creme de la 5.1" and my dad was
all about "better buy quality" & co, woke up inside the box with these sub-pertinax boards and just
godawful, and even more fun was that even the most basic stuff would fail if you put any mechanical
strain on the PCB. This happened to each and every one, even stupid parts like "power supply to light
bulbs", just...well...I bet your average repairman will do it twice and turn into Mr. "better buy new"
right on sight.
And yeah - with you on the reliability eng thing, not like you can really control something like that.
There's just el holder of los purse strings going "why bother". And you go "Well...I care, is why!"
And you get "I understand you, but can you find a workaround for that? My superior was talking
about the budget and it did not sound good". And you go "did it ever?"
I have experienced some outright destructive things on Swiss Electrolux refrigerators, though:
Specifically, the handle on the inside freezer compartment. It's not like you can't design an injection
molded part for stability, but in Switzerland, the fridge is always a built-in kitchen part, so whenever
somebody moves, the landlord makes them pay the 130 swiss francs (about a hundred bucks) to
replace the stupid 0.50$ injection part *they* broke after all.
And he just kinda shakes his head and says "happens every time".
all about "better buy quality" & co, woke up inside the box with these sub-pertinax boards and just
godawful, and even more fun was that even the most basic stuff would fail if you put any mechanical
strain on the PCB. This happened to each and every one, even stupid parts like "power supply to light
bulbs", just...well...I bet your average repairman will do it twice and turn into Mr. "better buy new"
right on sight.
And yeah - with you on the reliability eng thing, not like you can really control something like that.
There's just el holder of los purse strings going "why bother". And you go "Well...I care, is why!"
And you get "I understand you, but can you find a workaround for that? My superior was talking
about the budget and it did not sound good". And you go "did it ever?"
I have experienced some outright destructive things on Swiss Electrolux refrigerators, though:
Specifically, the handle on the inside freezer compartment. It's not like you can't design an injection
molded part for stability, but in Switzerland, the fridge is always a built-in kitchen part, so whenever
somebody moves, the landlord makes them pay the 130 swiss francs (about a hundred bucks) to
replace the stupid 0.50$ injection part *they* broke after all.
And he just kinda shakes his head and says "happens every time".
livingnote
Well-known member
Wow. What's you take on the vibration thing?
Oh btw...
Oh btw...
okgb
Well-known member
An M.I. store guy was telling me the other day
about being able to purchase " levels of quality "
from the chinese where the levels had increasing
percentages of expected failure rates right from the box
But that it was cheap enough companies would simply
buy them & sort them
30% rejection rate at a 40% off price kinda
and it would seem some companies don't even sort them
about being able to purchase " levels of quality "
from the chinese where the levels had increasing
percentages of expected failure rates right from the box
But that it was cheap enough companies would simply
buy them & sort them
30% rejection rate at a 40% off price kinda
and it would seem some companies don't even sort them
okgb said:
Do you know how to tell when a salesman is lying to you? His lips are moving. ;D
I have actually worked with Chinese contract manufacturer's. They don't engineer the products, they just assemble them, with the parts you tell them to use... If you don't manage the full process, don't expect them to make the same choices you would. If you buy a chinese designed product (I never did), they also market them by the features they contain, not reject rates.
Nobody in their right mind builds product expecting any percentage of a production run to not work. The economics of repairing or discarding even a modest percentage of a production run is onerous. The parts cost is the major expense and throwing away 99 parts in a unit because one part is bad, is a very bad trade. To support an even modest number of rejects would increase the cost of the rest significantly. It is way cheaper to just use parts that work in the first place.
A situation like the store guy is describing could occur after the fact, where some distributor has already paid for a container of crap and needs to blow it out. I did hear a story once from a Chinese associate about another company in the same industry who shall remain nameless, who specified such cheap parts that there were problems with a high failure rate at final test. The customer got into a pissing contest with the contract manufacturer who wanted to be paid for building the product with the parts the customer specified. They ended up parting ways. We had nothing but good experience with that very same contract manufacturer, but we specified the same exact parts as we used in our US builds. In any factory around the world, you only get what you manage. If you don't get that, you stop working with them.
JR
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