Chinese-Made Stereo Has a Meltdown
Engineer Andy Morris recently discovered an unwelcome feature among several Chinese-made stereo sets he owns: Shoddy work, leading to scorched pinkies.
Andy bought this Emerson model ES50 stereo new and to his dismay after 9 months of fairly light CD use (no teenagers in the house, presumably), the CD player literally melted.
Although the resulting product is likely the result of a series of bad-tradeoffs, Andy describes the key design flaw that resulted in the player’s quick demise and some scorched pinkies (his) : “The voltage regulator output transistor was mounted on the copper side of the PC board with a small amount of copper (almost none) used as the heat sink. It was required to drop 10 volts at 500mA, dissipating 5 watts of power. It failed and shorted out, applying 18 volts instead of 8 volts to the CD circuit, essentially frying the CD player. The voltage regulator circuit is similar to the one shown here except for no Q1, D1, D2 and a different zener diode.”
Click here to see Andy’s redesign of the circuit and transformer, though his warning to the wise: Stick with quality brands like Sony and Panasonic. He says:
“First, I replaced the transistor and put it on a decent heat sink, and I replaced the CD mechanism with an identical one from a junk CD player I had on hand for parts. That got it working, but a lot of heat would still build up inside the set. After about one hour of use, the CD player would start skipping and then stop playing altogether.
I figure that the CD servo chip was slightly damaged, by the 18 volts, making it more sensitive to temperature than it originally was. I’m amazed that it didn’t blow out completely. In any case, the stereo set got quite warm after an hour or so of use. I nearly scorched my finger on the voltage regulator heat sink, so I decided to do something about it.
In this set with a similar problem, I replaced a large dropping resistor and a 7808 voltage regulator with the switch-mode down converter circuit from a cell-phone car charger, readjusted to 8 volts output. Since it has a completely self-contained edgewise CD player, with a built-in 5 volt regulator, this fix worked well in that set. It did not interfere with the radio, because the circuit is turned off when the radio is in use. I tried this fix in the Emerson ES50 set, and got an error message when starting the CD player.
I thought of using an SCR pre-regulator that I have already published on the web but I felt that the high in-rush current when the SCR fires would interfere with the sensitive CD player circuit. I had to come up with something better. I thought of a circuit that Dave Johnson had created , where the output capacitor was charged on the rising slope of the rectified sine wave, instead of the falling side as in the SCR circuit. I designed a switch mode pre-regulator , using Dave’s idea, and that fixed the problem. The set still gets pretty warm, but now I can play the CD player for hours without problems.
The pre-regulator circuit is an after-the-fact fix. In a good design, the power transformer should have had a tap or an extra winding for the CD player.
Although the stereo set no longer stops playing, it still gets quite warm, due to the fact that the CD player uses 4 watts of power and the power transformer is poorly designed. All this is in a very compact package with very little ventilation.
Now, let’s talk about the power transformer — take a close look at the figures above. The compact design called for a “low profile” power transformer. Most people might miss it, but a transformer designer should have known better. To implement the low profile design, the designer just squashed the transformer down and spread it out sideways to get the required wattage. Note that this doubled the length of the wire needed in the transformer windings, doubling the IR loss in the transformer. Every low profile power transformer I have seen has the windings rotated 90 degrees from what you see here, so that the size of the coils is kept small, minimizing IR loss.
I have another compact stereo, the Emerson model MS3110 shown above that had little use, but that I wanted to see how well it was designed. It had the same overheating problem and so I installed the interference-free switch-mode pre-regulator circuit into it. The circuit shown shown above in this post is the voltage regulator from this stereo set. By the way, when installing the pre-regulator circuit into sets with this type of voltage regulator (which also acts as a power switch for the CD player), the best way is to disconnect the collector of Q2 and connect it to the 10 volt output of the pre-regulator circuit. You should leave the zener diode circuit alone, unless that circuit is also poorly designed as the circuit was in this case. View circuit
R1 and R2 are both tiny SMT resistors that can’t be more than ¼ watt parts, yet they’re dissipating almost twice that. You don’t need all this current through those resistors, anyway. I changed R1 to 4K7 and R2 to 1K.
Another thing; what the hell are diodes D1 and D2 for? They just waste power, seriously lowering the gain of the Darlington amplifier (Q1 and Q2). This requires one to push much more current through R2. I disconnected D1 and D2 with no negative performance effects.
In this set, I measured about 19 volts on the main power supply. The data sheet for the audio amp IC sets the absolute maximum allowable voltage at 20 volts. The recommended max is 15 volts. When I get my hands on a 7815 or an LM317, I’ll fix that problem.
Note that all these stereo sets were made in China and they all have about 10 watts of audio power. I have seen similar stereo sets at flea markets and garage sales with different brand names and slightly different styling. I would recommend sticking with quality brands like Sony or Panasonic. Please note however, that I saw a small stereo set very similar to the Emerson ES50 at a flea market with a JVC name on it. It also had a faulty CD player. JVC wouldn’t make a piece of crap like that, but they obviously resold it. They probably didn’t know at the time about the poor quality.
Many Japanese companies (like Sony, for example) are having products made in China for cheap labor, but they’re designed in Japan and subject to Japanese quality control.”
Richard in NJ commented:
I've seen dozens of instances of poorly constructed electronic and electromechanical components, counterfeit components and even used components passed off as new comming from China. It has become so bad that I now must spend 3-6 hours a week with our QA/QC Incomming Inspection guys doing random case-lot sampling and inspection of product to be certain it's not junk. I've been in this business since 1973 and if there's a "Made in China" label on the shipping carton I consider that a warning label. If Vhina can save a penny and get away with not telling you, thus sacrificing product integrity, they will do it. Trust me. I have the grey hairs to prove it.
Andrew commented:
A few years ago, while returning a half-dozen shoddy Chinese-made "Lights of America" fluorescent shop lights to Home Depot because they wouldn't start reliably when the temperature in my garage dropped below 50F, I happened to talk to a store associate who worked in the electrical department part-time to help pay the bills. His regular job was at Underwriters Laboratories nearby, an he told me there's a chronic problem with fake UL certification labels being applied to imported Chinese electrical and electronic devices. Moral: If it runs on electricity and is made in China, leave it on the store shelf.
Louis commented:
Isn't part of the problem that U.S. companies locate factories in China so they can exploit workers, ignore environmental regulation (what little exists), and avoid taxes?
You simply can't put all the blame on the Chinese. Look what happened in the U.S with the banks, mortgage lenders, GM and Chrysler. Not exactly a quality product, not to mention that they became "government subsidized."
Isn't China still a Communist nation? Most favored trading partner? Is Reagan turning in his grave?
robrob commented:
Can you say chinese drywall? Sure, I knew you could. Do you think the Chinese are going to pay the billions of dollars it is going to cost to rip out the hazardous drywall out of the hundred of thousands of homes it was installed in?
Accidental Beta User commented:
Many posters have said that the solution to not getting cheap products is simply not to buy them are right to an extent, but except in some cases that's not practical for an individual. The other 99.999% of customers who want to buy crap for next-to-free turns quality products into a boutique product that costs three times what it should. There are no economies of scale for that type product any more. If most people looked to buy quality products, they would be the norm and would certainly cost substantially more than the crap common today, but much less than what good stuff costs today.
Mike commented:
Just a side note. Emerson bought the (profitable)computer company I was working for in WI, shut it down and moved production to the Philippines. They are very open with the fact that their shareholders are their main concern, not customers or employees.
srlahousse commented:
I've done a good deal of business related travel in China and have seen the full quality spectrum in factories from dirt floors to fully automated behemoths that are world class. As the Chinese market matures they will start developing their own domestic brands independant from the private-label reverse-engineered manufacturing that constitutes the current majority. I know of several companies in clean tech that are coming to market with some very cutting edge products, within 5 years there will be some Chinese brands that will be considered among the best.
Rick commented:
As stated previously, we vote with what we buy.
If nobody buys it nobody will want to build it.
I'm a product manager and I watch what the customer wants not only with what they say but with what they buy. If there is little sales then we discontinue it, they just voted.
Nobody is forcing the people to buy it.
I have personally not bought something just because the quality appeared to be low and wanted to hold out until I found it in the higher quality I desired.
Sometimes I just have to go without and not have that immediate satisfaction of owning something.
DaveP commented:
Re KAMullins's comment about oats - yeah, I've recently had to make a decision about buying oats, and decided to get better ones than previously.
The microwave oven I bought back in the early 1980s (a Kenmore) lasted almost 20 years - through two moves, 15 years of family life, and a lot of meals. When it finally died a couple of years ago, I bought a newfangled "high-tech" inverter-based replacement from a well-respected manufacturer... and it quit yesterday morning.
Upon doing some research, I've concluded that there just don't seem to be any high-quality consumer-grade microwave ovens available on the market. Every brand seems to be plagued with reports of DOA, short lifetimes (sometimes weeks or months, or just after the warranty expires :-), poor customer service, poor build quality. With few exceptions the ovens are actually built in China. Competition for the lowest retail price seems to have triggered the "bad drives out the good" syndrome.
Researching the models available locally left me with no confidence that they'd still be working in a couple of years... and it offends my sense of value to just keep buying "disposable" appliances. I guess I'm tired of being offered oats that have clearly been through the horse already.
I decided to try something different this time. I've ordered a "light commercial use" microwave oven (Amana ALD10T) similar to what my company has in our lunch/break room. It comes at more than twice the cost of the most-expensive consumer-grade microwave at Costco, but I expect its lifetime will be a lot better than a "built to sell cheap" consumer model (it comes with a 3-year warranty). I'll probably end off spending less in the long run this way.
Cheap is often very expensive.
Stiggle commented:
Quality Costs...
How much do you want to spend?
Fix-IT commented:
Many years ago "Made in Japan" implied "Junk". Now, "Made in China" has taken over this distinction - BIG TIME!!!
Rich S commented:
Quality costs! There was a time when Emerson meant quality butnow I wouldn't give it the time of day. You get what you pay for!
drifter57 commented:
I read below of someone wary of the Chinese building cars. I think I would worry more about their proposed passenger aircraft.
Frank commented:
Another reader posted it: Like this is some kind of discovery ??? Must of been slow month, Karen; this is old news. For quite some time China has been taking our jobs and technology, selling us their crap, and buying our country and government with the money they make from us in the first place! What a set up! The big question is: why haven't you and your kind been squawking about this louder and more frequently???
Sbkenn commented:
I have had several Chinese products for evaluation, electronic and mechanical, and have thrown them all in the bin, with the exception of some LED strips which are fine ... even taking 24V when they were meant for 12 ! They ran quite hot, so I switched them to 12 rather than further risk of combustion.
MotoMan commented:
Albiet if you want good products is probalbly an understatement. The Major concern here is public saftey luckily no one was killed in these cases but im sure there are and will be an unlucky few that will loose homes possessions and even thier lives. We as a country must stop buying and supportting this influx of cheap deadly products from china. And as as much as i hate to say it we are to blame, supporting giant importers of this equip such as Wal-mart and bargain houses that specialize in cheap goods.
JOHNNY69 - Milwaukee commented:
Question:
What is the diffrence between a photo camera made in China, and one made in the U.S.?
Answer: U.S. camera goes "Click" when taking a picture. Chinese camera goes "Crick"!
AtomJack commented:
Indeed, quality costs. I see this all the time. I used to buy glasses cases, made in...China. There is nowhere else that I have found to buy one produced in. They fall apart, in as little as 2 weeks- the hinges crack off, the liner cracks, or falls out, etc. The problem people have is that they only look at the purchase price (and, yes, shop at Wally World). There is an expectation in this country that a quality product will be got for a low price. Based on the comments, it's generally true that the posters understand that this is not the case. But think about this: if you sell enough schlock, you will make your money. If people don't return, this is fine, the new corporate logo will fool the sheeple into buying the next bad system. It's terrible. The Chinese will end up owning the US of A at this rate. They sell:
1. Melamine in food (including your candy)
2. Lead in paint.
3. Ethylene glycol in cough syrup.
4. Drywall containing gypsum with a high sulfur content that is causing premature failure of wiring and plumbing in new housing.
It is a problem that is hard to control.
My solution for the glasses case? I made my own out of Bolivian rosewood. A comparable product would cost $60 USD on the open market, but I'll never have to buy another.
Mohan commented:
Hi Karen,
The reason that they are producing such shoddy products is because there's a market for such shoddy products BUT when the product falls apart then we start blaming the makers of the shoddy products.
Hey - let's face it - it takes 2 hands to clap, if we stop buying these shoddy products then all makers of shoddy products would vanish - yes poof!!!!
- Henry
Jon commented:
What are the engineers at Emerson doing while this goes on? Oh wait, they all lost their jobs and Emerson just private labels someone elses cheap designs. Sadly, that has been the pattern with many previously good names.
A realist commented:
The Chinese are selling what the customer wants - that's good old American capitalism. If you don't want cheap junk, don't buy cheap junk.
If enough people don't buy cheap junk, the manufacturers will make a better product.
Is anyone really surprised by this?
Bailie commented:
What we see as quality the chinese see as wasted effort. Lets hope their weapons financed by this stuff is of the same quality.
John commented:
You all quick to blame chinese for the faulty products they manufactured. How about Emerson, Walmart, or any other big box retailers that sells the low cost products without testing them and put their big name on the front?
Brad Wood commented:
The saddest thing for me is that at least for a while, cheap lousy products drive out decent ones. Yet it seems the people making the purchasing decisions at retailers for the most part just don't get it---they can't imagine that someone would be willing to pay for quality/reliability. They all have a mantra about quality (Dell used to say Quality is a given, when Harman would cite their outstanding record for same on powered speakers, for example) which is to pass over it quickly while haggling on price.
The price pressure passes through the supply chain, and the manufacturers in the far east often just don't know how to say NO! We can't make money on that! Lately whole factories have been closing, with tooling inside that belongs to the majors---as the impression is given that price is inelastic.
In addition, good design is difficult to teach and more difficult to learn, a fact that penetrates slowly into the brains of top management. Lately a number of consumer electronics companies are making plans to send the design effort to the far east (!). You think you've seen problems now....
Steve Jacob commented:
So their engineers make less than a grocery store bagger not that they aren't smart but that's all figured into the cost of the product. With the design completed in 1 week and just the minimum number of components to get the thing working you are able to purchase a $30 stereo that cost $15 to manufacture and deliver to Wal-Mart. I sure hope they never get serious about building cars!
sara commented:
Like this is some kind of discovery ???
Just take a walk up and down the aisles of your local big box retailer.
"Furniture" made out of MDF, cardboard, and staples (?!) Bicycles with critical fasteners that may hold tight the first time, but which - with any regular re-servicing - will fail. Oh - and the most important factor ? - hordes of consumers glad to spend their unemployment check on this low-cost junk.
It's a whole new definition of the word "junkies", but the behavior is (IMHO) the same.
pgdion commented:
"recently discovered an unwelcome feature among several Chinese-made stereo sets he owns: Shoddy work ..." - Recently discovered??? That's like the trade mark of Chinese manufacturing.
Paul Robinson commented:
I think there should be a change to the UL /NEBS specifications which calls for longer duration tests eg ; 1 hour , 8 hour rating 1 day , 1 week , 1 month, 1 year. If Design rules are so poor then legislation to weed this rubbish out is the only way. This is a fire risk and a safety/overcurrent/over temp trip should have taken it out in my personal view
tucsonics commented:
Many Emerson and Sylvania brands are made by Eastech. They used to build for Philips and a very good quality. NO ONE wants to have problems with their cheap gear. I have bought nothgin but the major brands who have tight quality control. Sony, Toshiba, Pioneer are three that I have had little or no quality problems with.
William Ketel commented:
What has been done to get a UL certification on the transformer is simple. Unfortunately, even an absolute piece of trash transformer that will fail in just a few hours can be UL certified. To get the certification all that is needed is to assure that the transformer can not start a fire or deliver a shock. So it gets a thick plastic bobbin and steel side covers. To avoid any chance of starting a fire they all get a very cheap thermal fuse embedded in the winding. The result is that the first time the transformer gets really hot, the fuse opens and a fire is prevented. Of course the product no longer works, but that is of really no concern to those who sold it, or those who built it. And of course there is the reality that making a transformer that is reliable will cost a bit more than one that is not very reliable. As for the "lower-form-factor" transformer, I believe that at least one company has been producing a reliable version of them for quite a few years. Check SIGNAL brand transformers. They wind up being less expensive because of never having to replace or repair them. At least, if you get the real ones and not the Chinese made knock-off copies, which look sinilar but are of a much lower quality.
Matt commented:
Why would you buy Emerson in the first place? Notoriously cheap and low end (crappy) electronics.
John commented:
We should have laws that require all importers to certify that the products they bring into this country meet health and safety standards at their own expense (which would be passed to the customer). The government should have an agency do surprise inspections also at the importers expense (which would be passed on to the customer). This expense would be so small that the customer would likely not notice it or the difference would not be enough to make higher cost sources significantly more attractive. This would have been especially helpful in the cases of stinky drywall and toys with lead based paints.
Since our government appears to be for sale to the highest bidder and appears not care about our health or safety, this will likely never happen.
A big issue with consumer audio is that such products have become so cheap that repairs are not economical. Since few of these items are really repairable (by the average consumer), we have no way to know whose product is good and whose is bad until after we buy. They also change so fast they do not get much of a chance to have a reliability/durability record. You can buy junk just as easily at a higher price as at a lower price.
dagohoy commented:
That is the cost of trading with China. We complain of the quality and the consequences, but we got excited with the price, not even giving a thought of the green house gases that were emitted because of the coal powered generators and bringing unprecedented climatic upheavals in Asia and in the USA.
DaveW commented:
Chris: And how do we know that the transformer is actually ULC certified? Stickers are easy to print. Even stamped logos are not that expensive.
KAMullins commented:
Quality is like buying oats. You pay a little more for good oats. If you want the ones that have been run through the horse already, then they are a little cheaper...
anatech commented:
Hi Karen,
The transformer is supposed to be ULC certified here. The manufacturer may make a stock model and normally has little idea what the end product looks like. So they are off the hook.
It's the company that ordered these designed as they are that are at fault, as well as the folks at ULC laboratories. They certified these (it has a sticker, right?).
As for poor design, this has been going on for over 30 years in the consumer electronics field. Nothing new there. I have seen terrible mistakes in design made by all manufacturers, including Sony (big time)and Panasonic. Be aware that anything made in China will never be as good as it was in Japan or North America.
If you want good, be prepared to pay for it. We all voted with our dollars, and this is what we voted for.
-Chris
