|Class D Switching Power Amplifiers and Power D/A conversion|
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|18th March 2005, 12:35 PM||#1|
Join Date: Feb 2004
Location: Recife - Brasil Northeast
Class D factories, there are decent people there.
As i came here and i attacked 41Hz.com , and i could see that
they are honest and taking care of the accident, i have to came here to say you that.
Problem is going to solution, the movement of 41 Hz.com in direction of some fair agreement is already made.
This show us, decense of those Management people.
I will thank you Mr. Sy , if you can attach this message to the closed thread.
Very fast in the trigger Mr. SY, yeah!...this is your job!
|18th March 2005, 05:50 PM||#3|
I don't think SY locked that thread, it wasn't "quite" there yet, he did make a good point though.
As someone already noted, most modules are like that. Look at the UCD "data sheets" on Hypex.nl, note #1 "Reversing polarity will damage the amplifier beyond repair", they should perhaps not use fine print for that but.... it's there.
In this case they at least give you that warning, and I think in lieu of protection, that's all that's required.
You had said your friend was at this sort of thing for a loooong time, which might explain the mistake. As someone who hasnt' done alot of it, that's the sort of thing I would have made sure I got right, checked, rechecked, and repeat X2.
Anyway one thing really caught my eye as a total rip off, I believe you mentioned 41hz modules had some sort of "gold" PCB, I would have gotten on them about that for sure, and I suspect others may have as well. So I just checked their site and they aren't using gold "whew".
"The PCBs are double sided, double weight copper with component prints on both sides."
Also the module makers cannot possibly account for every single mistake anyone could ever make. Something like reverse polarity ..... sure it's common enough, but how required is it really, just give a nice warning not to do it or else, and make sure the terminals are very clearly marked on the module itself.
If they started trying to add protection against every circumstance, no one could possibly afford them. Someone might think submersing it in a fish tank is a great idea... (is a bubbler cheaper than a fan?....hmmmmmm...)
What they all seem to have in common though is their willingness to keep the customers happy. I really admire that as good business practice. The alternative to that is they all become like B&0 with their ICEpower modules and not sell them to the average person, where we can then look foward to having to spend $10K+ on it because someone who "is" qualified bought it cheap and slapped it in a box for you, and charged an extra 9 grand.
All you have to do is plug it in right.
|18th March 2005, 10:05 PM||#4|
Join Date: Feb 2004
Location: Recife - Brasil Northeast
Had some points that turn me deep nervous with them.
But i am not nervous anymore.
Mr. Mateus received some mail with the suggestion to use some heat pistol to dessolder SMD and check for some fail.
Not so common retired people, old people, to have that equipment, the hot air dessolder or some kind of sophisticated pump of air.
This made me think they are trying to have a good conversation with my friend, but not going directly to the point.
He has 70 years old, and deep experience related human relations and the people that lived with him always the top culture level, not only in Portugal, but also in Marrocos and in New York.
This man fixed more amplifiers, Video tapes, Video cassetes and general appliances than one 35 years old man could see in all his life....he fixed those amplifiers, this is more near relation with the hardware than to see, or to hear.
He has more than 100 audio amplifiers done inside his home, but of course, made much more than that...i constructed around 3.5 thousand, i think he could make a big amount too.
See that my 3500 amplifiers did not left me out of the shame of inversion....i made it, and i repeat that mistake, and made it again, and again, and again.....was last year, when i received AKSA modules.... and Hugh turning crazy to keep his English education but beeing hot alike pepper, as thousands were made and worked since the first power on....but mine kits not!...and i was repeating to Hugh.
- What a hell Hugh, i am not an idiot!, i constructed 3237 equipments since today....i know what i am doing.... this amp is burning fuses, and it is all checked hundred times....HUNDRED TIMES CHECKED... this is the point to have some conversation with you, my friend forsure.
Always i used, since young boy, early fifties, a red wire to positive...a black wire to negative....and more recently, something alike yesterday in my mind, people started to make things simetrical to avoid off set voltage...to avoid to use output condenser to block DC current.
And i elected the blue wire as negative always wire.
And doing a lot of things....always those colors there.....and i did not check with the meter the polarity of my Red wire...of course is positive.... more than fourty years positive!!!!....but i forgot that i had some electrolitic condenser leakage in my bench supply....when i substitute the condenser...hehe.... i made the color invertion....and discussing with hugh.
This "thing" is not working Hugh!!!!
and he telling me daily:
Carlos, check it again and again..... thousands working Carlos!!!, some mistery in your side!
At same time, Mateus constructing the published AKSA design, the one published in solid state forum...or other older than that....cannot remember if Rodd Elliot board or not.
And Mateus saying that had problems to adjust bias....and Hugh lost many hair nervous with that....but keeping himself calm and helping daily, and beeing patient....thank's Hugh...a good guy you are.
He saying...impossible!...bias is easy to adjust, of set is microvolts!... this is the first time Carlos!!!
Well, i was inverting polarity...and Mateus another mistake, as i assemble more 2 pairs and no problem to bias or any other.
I inverted....for a week, and i did not check polarity..... 40 years beeing positive the Red wire...but that week was not positive!
And hugh monitoring.... check this, check that....and nothing, till i realise my stupid mistake...... i delayed a lot to say Hugh the true, so ashamed i was....my 3 thousand amplifiers had not value to me...i made the child most common foolish...the beginner mistake.... some absurd to someone alike me, full of International degrees in electronics, in practice repair.... a damn shame on me.
And i measuring 9 volts from base to emitter..... why not explode...and not openned the junction...what a hell...this is impossible....and not hot...not shorted!, not hot the transistor....the voltage i was measuring was some small oscilation of first stage that could work inverted because some condenser charged.... the analogue instrument was rectifying the AC voltage of the oscilation and showing me as enormous DC voltage..... 600 milivolts was expected there..... 9 volts and i did not realise with that ENORMOUS evidence, that was inverted!
If we are humble, we can accept that those things happen to everyone.... i am here to say that...Mateus and many others.
Invert polarities is very normal, this is happening everyday, everywhere.
So, if Mateus inverted, he failed....and if the Board he was assembling did not considered that possibility, both failed!
If both failed....some agreement must happen.
But conversation going and returning, Mateus shy to say he wanna a new chip....and people saying he must use good tools, check twice and many things, hot air dessoldering....and not happening related to fix the amplifier....nothing able to result amplifier fixed, as short circuit inside chips cannot be fixed with hot air pistols...and Mateus not telling directly to them what he wanted.
By this reason i start some figth, i must confess that i was to much hard with 41 Hz guys...but now is too late, my time machine is not working!...already done.
Forsure, come on man!..... protection are two cheap diodes!
Kits are made for all guys, starting top Enginneers to first time soldering beginners.... people can make a lot of mistakes, cannot avoid the zilion possibilities...but that possibility, some invertion, is the one is most dangerous and more easy to happen.
The possibility of Ion radiation that arrived here in our planet, having the cause in "Orion", of course cannot be predicted...but invertion.... 50 percent chances man!....and calculate when you have three wires!
They are a factory to sell kits to users, not specified the man graduation....the condition is have the money and pay, capacity to read instructions were you can read:
"Carefull with invertions"
And fuses are there to burn if you invert, diodes will drain and fuses burned will interrupt....very small current fuses and chip died.... so...no protection....or.... protection failed.
Well, i am talking too much...and they are in contact to find a solution to that problem.
Yes class D for sure, people can believe hat invertion is not some possibility to take into account....yes, you are not defending that this is not to Kit industries worried about.
Hugh Dean put diode there.
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