Use of primitive tools

Sorta correct - theres a large lot of electronics (digital) devoted to getting the software decoded digital signal onto the screen, either LCD or plasma. Has to map and address the screen in an X-Y plane - most of this is build into the panel at manufacture, so replacement is costly . With plasmas, its the high power/high voltage driver boards that die, with LCD its the back light inverters....haven't had a chance to pull one of the newer LED backlight panels to pieces yet....

The real issue with digital TV's is you cannot look at the screen and get some idea of where the fault is, unlike analogue. They either work, or they don't. No schematics available, fix by board replacement. Totally uneconomic (except as a "interesting problem") to reverse engineer to component level.

But thats true of most modern goods, except for Old Farts like us who will spend a day machining a 10c part to fix a $20 machine....its not economic, but we do it becaause it annoys the hell out of us that "spare parts" is nowadays an oxymoron.

And back in the Old Days - why, I remember when I had to walk 10 miles to school, barefoot, through the snow with nothing but a pointy stick to protect myself from wolves. And this was after I had got up at 5am to milk the cows and do my chores, breaking ice in the well to draw up water for my mother. And if I hadn't taken a bundle of firewood with me for the school heater, I was whipped and made to go out in a raging blizzard and find some.....

And you tell the young people this, and they don't believe you.

Andrew VK3BFA.

You had me right up till the end - there's no wolves in Oz.

And they have a reason to not believe you when you get a critical fact wrong, people start tugging on the other threads to find any other loose ones - and soon the whole thing unravels. ;-)

Now then...

The Manufacturers of all electronics should be REQUIRED to release full schematics into the public domain when the unit is out of production and no longer supported, and the replacement circuit boards are no longer available. Because old gear sometimes must be repaired when there are no new replacements available for them, and you need the old gear to read the old media.

When the museums and media conversion companies need to keep (for example) old LaserDisc units, or 9-track computer tape drives, or Colorado computer backup cart drives, or 4-track or 8-track carts, or

8" Floppies, or AMPEX 2" helical-scan videotape players, or 3/4" open-reel videotape, or U-Matic or Betamax videotapes... And you are fast running out of working units... THEN it pays to do component level repairs.

And without the board schematics and the realignment procedures, and the Super Seekrit conversion list of proprietary chip numbers to the industry-standard chips they had relabeled, it can be almost impossible to fix the unit - unless you were the engineer who built it in the first place.

...AND you can remember what the hell you were thinking forty years ago when you were building it, which can be the bigger problem.

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I should have said dingoes - I was using literary license to make it readable in a different cultural context.....

Spot the deliberate mistake....

Agreed - now, if we can get the World Government (sorry Gunner) to legislate this, we would have a chance....

Bloody Hell Bruce - I have trouble remembering what I did 6 months ago

- I open up a chassis, recognise it as something I have worked on before, but.......its gone........never used to make notes as my memory 20 years ago was fine - now, alas have to ask the nice lady in the bank for my account numbers as I have a brain fart and cant remember...

BUT - the REALLY NICE old gear had beautiful manuals , old HP , Tek test gear, even till the 70's radio gear - again, its the Old Fart syndrome, we remember (I think) when such things as manuals and spare parts were routine. And if there was a problem, you contacted a service engineer in the relevant company who would be only too willing to assist....(now,its a call centre in India running a script on their PC screen...)

Sometimes work in a local TV repair shop, 3rd world environment as the margins are so slim - they have a Chinese tech, red hot. He is able to ring up the Chinese factory and really pay out on them until they email us the schematic we want....dont know what he says to them, but its very impressive in spite of my not speaking any Chinese...

Andrew VK3BFA.

The digital radios I worked on sometimes had hardware Matched Filters between the A/D converter and the DSP.

The too-far-ahead-of-its-time color ink jet printer used custom ASICs to remap linear images onto the multiple ink jets. These functions could be done in either hardware or software, the choice sometimes depending on the skills available on the development team. Twice I was temporarily promoted from lab tech to custom IC designer to help.

When circuits include a PIC or other programmable device the schematic isn't enough. Little stubs of circuity stick out of it with no hint of when or how they are active. Once a member of the original design team leaves some faults in the product can become impossible to diagnose and repair even in-house.

Companies don't release unpatented "trade secrets" hidden in the software.

Devices like these are an extreme example.

compiler includes a randomizer so that for instance it won't repeat a compilation that assigns a critical clock signal to an excessively long path. This means that the very same schematic may work perfectly one time its compiled and not the next. I spent quite a while driving between my CAD room and the radio site, through the snow and wolves, trying to get every function working.

If you want to pursue this line ask Microsoft to release operating systems into the public domain after they stop supporting them.

How is all this a Primitive Tool???

jsw

[snip]

A subcontractor had exactly this problem in the 1990s. Drove them nuts because while the compiler was randomizing paths and pinouts, the artwork on the prototype board strangely didn't automatically rearrange itself to follow.

Completely stopped integration until the engineer broke the undocumented proprietary CAD file format and figured out how to force the pinouts to remain stable.

I don't see how randomizing paths and pinouts helps their sales or protects anybody's intellectual property. I bet this comes under the heading of "don't ascribe to malice that which can be adequately explained by incompetence".

Joe Gwinn

Auto-routing is something like chess, a pattern-recognition problems that a human can sometimes do better than a machine. As I understand it randomizing prevents the tightest routing channels from filling up and blocking completion the same way each time. The PADS autorouter I used in the 90's would jam in ways I could easily see how to fix by moving components, since I could evaluate the effect of lengthening their interconnections.

I never met another PC board layout person who understood the circuit, let alone had designed it, so the tool had to be able to fix its problems automatically.

Xilinx explained their randomizing algorithm in the thermodynamic terms of metastability, the peaks and valleys of activation energy, which I followed from knowing chemistry but won't try to explain here.

jsw

You forgot, It was UP-Hill both ways. ...lew...

On a cool spring day I was sent down to stoke the wood furnace just after lunch, by 2 PM we were sent outside because the classroom was too hot to stay inside. I never got asked to stoke the furnace again! Gerry :-)} London, Canada

That makes sense.

This is OK for the paths between the in and out pins, but not for the pinout.

I do understand. They are using simulated annealing in hope of finding the global optimum without becoming stuck in some local optimum.

Joe Gwinn

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Not only that -- but Tektronix, at least, had a sense of humour. Look in the schematics for something from the period of the 454 and you will find, somewhere in there, a joke. In one of them, there was a railroad train running along the ground rail on one page, complete with puffs of smoke and steam. :-)

I forget what the other devices had, but there was one schematic for each device which had an "Easter egg" like that.

Enjoy, DoN.