The whole SMPS thing...

Too true Ron

TV CRT SMPS are probably meant to fail. Crappy design and all....but easy to repair.

I mean I have an Acer lappie here that has endured everything that has been thrown at it....but it is powered by a Delta Electronics SMPS..
I have spoken before about SMPS design being a "Dark Art".....

Well, both lappie and SMPS are both well after Nine Years now

We have power surges here and brownouts...customers bring their sets with blown SMPS's the next day for repair..

I am right here in the midst of this...yet my little sealed Delta Electronics SMPS supplying power to my lappie has never needed repair..

Sometimes I shake my head and just want to walk away....

The Guys that really know SMPS are the likes of Delta Electronics. Not Mickey Mouse me.

Regards,
tv

Nigel Goodwin said:

I was talking about CRT sets

Click to expand...

Hello Nigel

You are wearing my patience thin. From chucking CRT's away to suddenly being an expert as to what we are fixing here now

You are not here.

Please stop questioning all technical posts I make. I live the stuff I talk about. I do not make make it up to try and impress people.
I have absolutely nobody to impress.

Thank you,
tvtech

Power companies ...

As built, the station had over voltage and under voltage detectors that autostarted the generators and shifted the unit to generator power. And yet there still were occasions of non-usability. They added a recording device that monitored the three phases for over voltage, under voltage, frequency change, loss of 1 cycle, etc. The unit was at end of line for the power company so the power company's load shifting was always seen there.

All of those plus acts of GOD, lighting, etc. What I found in a lot of power supplies that were connected to the mains was the two diodes of the bridge that were tied to the AC return line were defective. The return line is what most people call ground. Consider the impulse of a lighting strike. That impulse is not distributed via the hot side of the AC power, but the return side. 150kA peak 5 microsecond pulse hit's close to a house can take out the compressors of your freezer, refrigerator, computer SMPS, television power supplies, et al. I've seen each of those faults.

I've known people who increased the inductance in their power line from their television by tying the cable into a series of knots, increasing the inductance of the cable with respect to an impulse. There are many ways disturbances can enter into a television, from power to RF.



Good luck on your troubleshooting.

Laptops ....

I've replaced the external power module for my laptop, and batteries for my laptop ... keep in mind that I've owned laptops for over two decades. My wife also has owned laptops.

With the external power modules being so inexpensive, very few people will bother to waste their time on component level repairs. The economics of repair is the deciding factor in most cases.

tvtech said:

Hello Nigel

You are wearing my patience thin. From chucking CRT's away to suddenly being an expert as to what we are fixing here now

Click to expand...

I've been fixing CRT sets since the early 70's, it's only 'recently' that they just get thrown away.

You are not here.

Please stop questioning all technical posts I make. I live the stuff I talk about. I do not make make it up to try and impress people.
I have absolutely nobody to impress.

Click to expand...

I'm simply expressing another professional point of view, rather than assuming yours is the only one possible - not criticising you in any way.

While I have not done any mains projects I have designed my own SMPS using discrete parts (like op-amps and transistors). Despite it being very simple it works incredibly well! It has negative feedback too so the output is regulated properly. Im sure though if I just connected it to a transformer with a rectifier it would work.

Robin

JoeJester said:

Power companies ...

As built, the station had over voltage and under voltage detectors that autostarted the generators and shifted the unit to generator power. And yet there still were occasions of non-usability. They added a recording device that monitored the three phases for over voltage, under voltage, frequency change, loss of 1 cycle, etc. The unit was at end of line for the power company so the power company's load shifting was always seen there.

All of those plus acts of GOD, lighting, etc. What I found in a lot of power supplies that were connected to the mains was the two diodes of the bridge that were tied to the AC return line were defective. The return line is what most people call ground. Consider the impulse of a lighting strike. That impulse is not distributed via the hot side of the AC power, but the return side. 150kA peak 5 microsecond pulse hit's close to a house can take out the compressors of your freezer, refrigerator, computer SMPS, television power supplies, et al. I've seen each of those faults.

I've known people who increased the inductance in their power line from their television by tying the cable into a series of knots, increasing the inductance of the cable with respect to an impulse. There are many ways disturbances can enter into a television, from power to RF.



Good luck on your troubleshooting.

Click to expand...

You always make sense Joe. Just thought I should say it
I know and understand what you are saying....

I believe you know loads more than you are willing to share here. For some or other reason you hold back.....maybe burnt in the past....

Song for you:

Never been burnt, mostly because I never made the issues personal, just stated the facts.

In fact, I did write one letter to the Commanding Officer of a support unit, stating that the Engineering Change Order they installed was asinine. Of course, my friend at that unit told me my name was mud with all the engineers, civilian and military, but none could contest what I said was wrong and why it wasn't asinine. I truly wanted to say f&^*ing stupid, but choose a better adjective in official correspondence that I signed.

I told someone who was the top person in the program that his description of how things ran was an utter fantasy There were a bunch of senior officers and three of the enlisted officer in charges sitting around a table socializing and a few problems were being discussed. The senior officer who received that letter I mentioned above was there. Every officer sitting at that table was a shipmate on one of the many previous units, so the talking was unvarnished, between them and I. If they didn't like what I said, they shouldn't have asked the question. It's been unvarnished between us since day one as shipmates.

That is the way it should be here. Going off on a rant erodes respect, as some will see with clarity the ranter. If the intercourse between professionals can not be unvarnished, cogent thoughts will be missed.

I tend to go with two simple rules: 1. Theory works. 2. In the unlikely event the theory doesn't work, then you are looking at the wrong theory. Refer to rule 1.

As far as things being "different" in the various locals, sure is. The populace is different and the interactions is different. One thing is constant ... electron theory doesn't change because of the locale. Neither does troubleshooting techniques. I've had people tell me "it doesn't work that way here" a lot of times. Not one of them has demonstrated where there was a different theory with a circuit because it was "here" and not "there".

Tread lightly and look for the value in everyone's comments. Rants decrease creditability as fast as being incorrect.

So, what is the isokeraunic level for your area? Here is the map From there you can estimate how many lightning strikes per square mile you will receive ... and from the population density, you can estimate your potential customers.

WOW Joe.

I understand and respect people like you. I am also not a kid born yesterday. I joke a lot...but I also listen.

I was in the South African Signal Corp in the "bad old days"...sworn to secrecy as far as our comms went. We had Signals equipment of note up there fighting the enemy now which is ruling us because of mass voting and "democrazy"..yes democrazy. Not democracy.

Hoppers were the best. Grinaker and I think maybe another out there ( Recal...) cant remember now...built these Masterpieces..

Every Evening at +- 6PM ....both units had to be synched...we could talk to from our HQ in enemy territory to base far, far away. 2 Hoppers working together and the enemy did not have a clue what is happening...I as the Signalman responsible for all this always had holes in my clothes..always.

I had to get our Hopper up and running...heavy but doable. Batteries always spilled acid on me though. No matter how careful I was. A Hopper used 2 big truck batteries for it's 24v supply.

Eventually I became a standing joke. Holy one or something like that.... I always looked like a Hobo.

But you know what....I loved every Minute of it. The satisfaction I got when I knew I had made comms possible for my CO on time every time was always all I cared about.

The smartly clothed hyenas giggling and watching me from a distance never worried me.

And to this day....I am the same. All this took place around 1981-1982 where I was still a kid of 18 to 19Years old.

I did build an SMPS once, just a project, one-off job. It worked too, for a bit, and then made one helluva bang - there where actual flames and everything!

This thread got me thinking so, just for a laugh, I've dug out the schematics forthe entire amplifer project that the SMPS was part of. Never worked propperly, needless to say!

On a more sereous note, I've found that a variac/isolating transformer combination with a switchable series lamp for current limiting has been a simple but invaluble tool for repairing off-line SMPS.

tvtech said:

OK. We have very valuable Members here. Some extremely good minds. Good as in the best on the Internet. Par Excellence. In other words people only reply to stuff they know. Properly.

So the whole SMPS thing.....have any of you actually built a SMPS that runs off Mains??.

And not only one...but a few??. I am talking maybe to production. I ask this because SMPS these days is being touted as "easy". Every Tom, Dick and Harry thinks they can do it..

Trying to stop a stuff up before it goes Viral...

Regards,
tvtech

Click to expand...

Hello there,

When i worked in the industry that's what i did. We designed mostly synthesized sine wave converters, from maybe 100 watts up to around 30 kilowatts, and some other smaller DC ones. That was back in the 1980's. Here are a few interesting facts about the devices and parts.

First, the line voltages ranged from 120vac up to 240vac, and three phase types 208vac line to line or line to neutral. Frequencies usually 50Hz, 60Hz, 400Hz, or variable.
Second, when i started with one company the available transistors were ONLY bipolar, no high power MOSFETS yet at that time, and they were very very big and heavy with all copper shell and maybe 5/8 inch threaded stud mount, they were slow, and they were 250 dollars for one piece. Some time later we got large plastic package transistors that bolted down and were 100 dollars for one, rated like 100 amps at maybe 250 volts.
Input and output requirements sometimes meant that no transformer was needed, but that was kinda rare.
In the synthesized sine models the switching frequency could not be too fast because the transistors were slow. Later things could go faster as the newer transistors rolled in. I got to design the first MOSFET converter, which was only something like 100 watts or so. These used mostly TTL chips but then later we went to an ASIC design.
The 30 kw three phase units were huge housed in giant metal cabinets. They were also loud when running. The output transformers weighed in at over 100 pounds each.
The inductors we used for the first non phase locked model were very large too, wired with #6 wire or something like that.
The capacitors used for the input power filtering were huge high quality electrolytics, rated at maybe 300vdc and 10000uf each, with many connected in parallel using thick copper buss bars with holes drilled to accommodate screws right into the top of the electrolytic caps.
I dont remember all the details now but these were some.

I also actually built some of my own DC ones, actually quite a few for my own purposes. Mostly low voltage like 4 to 15 volts.

Hi MrAl

You are such a kind and giving person. It takes a lot to share knowledge accurately on a Forum such as ETO where people know stuff but don't always talk.

You see, I have been here for maybe 5 Years now. And only now after all this time are some people sharing knowledge.

You remember Flyback that always asked questions...he has started helping here too now. He is a Diamond. I think all he really needed is for someone to tell him he knows what he is doing. Because he does.

He was wanting us to polish him....make him perfect...meanwhile, he knew the answers to most of his questions anyway. Just wanted confirmation.

Proud of you Flyback and all you have achieved.

Giving Technical advise is a very hard thing to do unless you know you are 100% spot on. Especially on the Net where people like to shoot you down.

So, that is why I believe we are sitting with more Gold here at ETO. Lately some members here who never get involved with stuff are chirping absolute Gems.
Out of the blue

And accurate advise too.

Love it,
tv

Excellence is an art won by training and habituation. We do not act rightly because we have virtue or excellence, but we rather have those because we have acted rightly. We are what we repeatedly do. Excellence, then, is not an act but a habit.
------Aristotle

on edit .... one more to whet your appitite ...

If anybody tells you in order to support his opinion that he is in
possession of proof and evidence and that he saw the thing with
his own eyes, you have to doubt him, even if he is an authority
accepted by great men, even if he is himself honest and virtuous.
Inquire well into what he wants to prove to you. Do not allow your
senses to be confused by his research and innovations. Think well,
search, examine, and try to understand the ways of nature which
he claims to know. Do not allow yourself to be influenced by the
sayings that something is obvious, whether a single man is saying
so or whether it is a common opinion, for the desire of power
leads men to shameful things, particularly in the case of divided
opinions.
-- Moses Maimonides (1135 - 1204), Medical Aphorisms

JoeJester said:

Excellence is an art won by training and habituation. We do not act rightly because we have virtue or excellence, but we rather have those because we have acted rightly. We are what we repeatedly do. Excellence, then, is not an act but a habit.
------Aristotle

on edit .... one more to whet your appitite ...

If anybody tells you in order to support his opinion that he is in
possession of proof and evidence and that he saw the thing with
his own eyes, you have to doubt him, even if he is an authority
accepted by great men, even if he is himself honest and virtuous.
Inquire well into what he wants to prove to you. Do not allow your
senses to be confused by his research and innovations. Think well,
search, examine, and try to understand the ways of nature which
he claims to know. Do not allow yourself to be influenced by the
sayings that something is obvious, whether a single man is saying
so or whether it is a common opinion, for the desire of power
leads men to shameful things, particularly in the case of divided
opinions.
-- Moses Maimonides (1135 - 1204), Medical Aphorisms

Click to expand...

Hi Joe

Do you ever let your guard down....even just a little??
Like joke a little bit maybe..

It won't cost you an arm and a leg here..

Regards,
tv

I am always in a humorous mood.

Unfortunately, without using emotes, the sarcasm, humor or even sea stories don't convey well in written english.

Imagine if you ran something thru a non greek or non roman translator and reran it from that other language back to english.... The messages might not resemble any thought you had originally posted.

Mathematics is a rich language. Have you considered using the appropriate operators to express your emotions? John