Lair Of The Multimedia Guru

July 14, 2018

Chinese worklight repair

A while ago i bought a quite cheap flashlight/”worklight” from aliexpress. Not the best quality but it worked.

About 3 days later its button started to work only intermittently. A few days later it basically didnt work anymore.
I wonder why these items have so many 5 star reviews.
Yesterday after putting some food in the oven in the morning i had some time while waiting for it.
After disassembly, it looks like this:

The button is a standard SMD button, i had some equivalent replacement.

After exchanging it, it works again. Lets see for how long …

Almost forgot, the failed button after gentle disassembly:

Filed under: Electronics,Off Topic — Michael @ 22:14

July 7, 2018

Copyright EU #3

The EU Parliament has rejected to fast track, (that is to pass it a few days ago) the controversial directive. IIUC it can now be modified by politicians and will be voted on again in September. Parliament debate and vote from 5th july 2018 (note this has subtitles if you do not understand the MEP who speaks in his native language).
If you care about this, you probably want to stay active and keep an eye on how this unfolds.
Also for those not seeing the problem, think about just sites like wikipedia and how exactly upload filtering (that costs money) or some link tax would work for them. Or how free software projects like FFmpeg could run a bug tracker where people upload small samples of media files which trigger bugs. Of course who and what this directive might affect depends on the very fine details how it is worded and also how the actual implementations in law in each European country will be worded.

Filed under: Off Topic — Michael @ 11:04

June 22, 2018

Copyright EU #2

2 days ago the EU JURI committee voted in favor of the controversial art 11 and 13 of the copyright directive. This was not totally unexpected. Next the whole EU parliament will vote on this so theres still a chance to talk to your representative, if you care. If that fails too, the next EU election is 2019, that is next year. The relative closeness of the next election may improve chances for politicians to care about what the consumers and companies they are supposed to represent want. Iam also still wondering who actually benefits from this law. I thought lawyers would but it seems even some lawyers don’t like it. If you speak german heres a video from a german lawyer about this.

Filed under: Off Topic — Michael @ 11:03

June 16, 2018

Copyright, EU

In 3 days, the EU JURI committee will vote on the copyright directive. If you live in the EU (and under a rock and are unaware of this). Then you may want to look at what this is about and potentially contact your representative member of parliament.

Below is some unrelated rant/chatter about copyright, please ignore if this doesn’t interest you.

Looking at the state of copyright and how it changed, over teh decades makes me a bit sad. Iam no lawyer and only know things roughly not detailedly but. The long term trend of more rules, more restrictions, heavier penalties. Its really a slap in the face of the consumer, the companies between and i would argue also the content creator.
Now why is all this which seems so great for content creators at the surface actually not. First, all the extra regulations we already have and the potential future ones we might get, require substantial resources, time, human, financial and technical to follow. They must come from somewhere and it is from money that is taken out of the consumer -> content creator chain. Do these laws produce more paying consumers than they add cost?

And then theres a completely separate thing. Why in a world of democracies, that is places ruled by the people do we pay those who restrict content and knowledge while we do not pay those who give content and knowledge away freely to everyone?
Hundreds of years ago it was impossible to give information/content/knowledge/music/films away for free to everyone. Because the paper for a book, the musicians turning written notes into audio all cost resources. It made sense to pass some money from the act of copying which was expensive to the content creator, the copyright owner. But today where the act of duplication is essentially free still doing this is simply insane. Its restricting who has access to basically public content without anyone having any real gain from it.

You could look at it like this also: Someone creates the worlds best operating system and gives it away for free to everyone, allowing everyone to change, adapt and improve it. Maybe billions of people use it daily, surely the governments who collect trillions of tax $ would pay him and the people who also worked on it something for the public service they did ?
OTOH, large and rich groups managing content/information/knowledge/designs/…, restrict it very heavily using every law, regulation and trick. And surely our politicians who represent us, the people of this planet would make laws that require these groups to make their content/information/knowledge/designs/… available for everyone before they could legally be allowed to collect payment?

Maybe the thoughts above, especially the 2nd are too extreme, too radical, i dont know. And no question this view is over simplified. But i cant see how the direction, in which the copyright law is moving, helps anyone except maybe lawyers. And at some point, heck maybe even lawyers will be against this…
Ironically, IMO even the movie industry would financially benefit from a change. There are surely many possibilities, one would be
Find out how many people watch/use public domain content (these statistics are already known) pay the content creator from taxes in a way thats related to how much her content is used.
With this there would be no need for any restrictions, and no motive for piracy. It would eliminate all copyright infringement of that content, all resources for dealing with regulations or violations. Thats alot of resources that are not wasted and thus there would be more left for the content creators.
Compare this to all the laws and regulations we have and which are planned, none of which will make any difference to piracy and copyright infringement.
Of course in reality its more complex than this, but personally from my view from under my rock, it seems the old style copyright is slowly being replaced by new systems even with all the apparent efforts from our politicans to prevent it.
For example i have not watched any “hollywood” movies since many years, in fact i also have not watched any “classical” TV. Simply because there are so many content creators today who happily give their content away for some ad based payment or for free. Basically unrestricted. One can watch what one wants, when one wants and how one wants. Also the breath of content to choose from is many orders of magnitude larger in the “basically free” segment than the restricted.

Filed under: Off Topic — Michael @ 23:44

November 26, 2017

DDR3 SO-DIMM in 2017 part2

After running into the row-hammer issue with new DDR3 SO-DIMMS for my notebook, ive tested all my used computers ram. I think i had tested at least some of it previously. These where DDR4 Micron Technology 16ATF1G64AZ-2G1A1 and CML16GX3M4A1600C9 from corsair. Both showed no issues on multiple passes of the row hammer test. Ive also now obtained new SO-DIMMS for my notebook, M471B1G73EB0-YK0 from Samsung and HMT41GS6AFR8A-PB from SK Hynix. Both as well have shown 0 issues in the row hammer test on multiple passes. So it seems that the issue is not as widespread in 2017-11 as looking at a set of 2 modules would have suggested. Ill return the faulty modules …
Iam a bit curious who the manufacturer of the chips on the faulty modules is but there are stickers over them and as i want to return them i dont want to peel these off. And in dmidecode they are just listed as “Corsair”. I guess if Corsair wants to make it hard to find out who made them, they will have to take the blame here.

Filed under: Hardware — Michael @ 2:51

November 19, 2017

DDR3 SO-DIMM in 2017

My notebook has 8gb ram and without swap occasionally that was not enough. So i thought hey trivial put more memory in. And while online resources disagreed on the maximum supported for my Acer Aspire V3-571G. It seems fine with 2 8gb sticks. But …
When running memtest (MemTest86 V7.4 actually, which was the first google pointed me to). It displayed after a while a note, “[Note] RAM may be vulnerable to high frequency row hammer bit flips”. After a short wtf moment, and a bit of research, this is a hardware bug that can be used to flip bits one normally has no access to and exploit an affected machine. I think i did actually read about it years ago but did not immediately connect the note message to it.
But what i find really disturbing is that we have november 2017 many years since its known. And these are newly bought sodimm modules (brand name in fact from corsair, CMSX16GX3M2B1600C9. Both of the 2 modules alone also are affected.
Un-voluntarily that also leads myself to the question, does anyone know of similar sodimm modules (can be slower i dont care) which do not have this issue? Or a way to increase the ram refresh rate on a notebook where this seems not available in BIOS? (I guess i could go read the chipset datasheets but maybe some tool already exists …)

Filed under: Hardware — Michael @ 18:45

November 5, 2017

Genetics history

Maybe a little off topic. But if one looks at DNA sequencing technology, in 2001 sequencing one humans genome cost 100 million USD, in 2015 it was down to slightly above 1000 USD. Today in 2017 you can buy a new DNA sequencer the size of a mobile phone for 1000 USD. Considering this, humankind today basically has the technology to sequence every human genome.
If someone asked me 10 years ago, what one can do about inherited genetic diseases or any thing else genetic. I would have said, wait 200 years till we have molecular-nano-technology and hope WW3 doesn’t happen. But in 2015 Chinese researchers edited human genes in embryos with some success. But still thats basically individual cells in a lab not an adult made of 1013 cells. But in fact similar methods have already been used and demonstrated to also work with individual organs in vivo in adult mice (not sure who did this first or when, but google finds quite a few things). And what i read few days ago according to interim results, non human primates, editing over 20% of liver cells successfully after a single dose and no adverse events with multiple dosing.
Now one wonders a bit, if one extrapolates this, where this tech will be in 5, 10 or 20 years. I think the next decades will be very interesting in this area.

Filed under: Off Topic — Michael @ 0:41

October 7, 2017

Samsung CLP-365 Laser printer paper feeder repair

About 3 months ago my cheap/small color laser printer stopped eating. It tried but most of the time it just failed and very soon it completely stopped working, giving a generic paper stuck kind of error so i had to take it apart and fix it as i needed it. I am writing this 3 month after fixing it, as i didnt had time before, but maybe its still useful for someone.
I have the suspicion all printers of this design will fail this way.

Disassembly

The printer is held together with screws and little plastic hooks, below are some pictures of my disassembly of it. The part we need to get to, is a small steel part which is moved by a solenoid.





Below is the part that causes the problem, the sticky foam thing on it has become slightly sticky on the wrong side and is also squished. The device still works if the solenoid is pulsed with sufficient power.

Repair

This is very trivial, remove the decaying black foam thingy and replace it with something that is non sticky on one side and
has dimensions somewhat similar to the original. I used very strong double sided tape to get the thickness and covered in chinese “blue” painters tape from my 3d printer to make it non sticky on one side. If you can, test that the solenoid works before reassembly.

Reassembly

Just undo the disassembly in reverse order, weave all the wires back in as they where before.


3 Months since the repair above, my printer still works and had 0 paper feed failures (unless it run out of paper).

Filed under: Hardware — Michael @ 18:12

June 24, 2017

Stepper motor vibration damper lifetime

When i installed the vibration dampers a few months ago on my 3D printer. I wondered how long the metal to rubber connection would last. One or 2 days ago my extruder started to skip. After checking it and the hot-end for clogging, i found the vibration damper was no longer in good shape. about 50% of the rubber had separated from the metal.
Thus the lifetime of that one was about 2 months with low to moderate use.

Somewhat expecting this i already had a bag of replacements and replaced it. Lets see if this is a one time failure or if this repeats. Opening the arm of the extruder when not in use should reduce the stress on the part though. But until i see a repetition of this failure mode ill leave things as they are. So as to exclude that this is a one off faulty part.

Low cost 3D printers (in 2017) are “fun”, theres “always” something that needs adjusting or fixing.

Filed under: 3D printer — Michael @ 0:04

April 23, 2017

Tevo tarantula and flex filaments

The extruder of the tarantula is capable of printing flexible filaments. But its not good at that.
What worked best with the original extruder was to push the bowden tube up to the gear of the cold-end and to disable retracts.
With that it was possible to print stuff at 15mm/sec with some success. 30mm/sec did not work for me, at that speed the filament found a path of less resistance than the intended. That was with 0.4mm nozzle 0.2mm layer height.

To solve that, the cold-end of the extruder needs to be replaced. Looking at thingiverse i found several printable extruders that looked like they should be better. The one i printed and tried first was the RSE-2 extruder. Which worked a lot better but required hacks to make it fit. It needed a spacer, to not hit the x carriage, required a separate piece of smaller diameter PTFE tubing, M5 coupling instead of the M6 i had from the original extruder and was not really well mountable with the 2 screw based vibration damper i had.
So i modified the RSE-2 extruder to correct all the issues i did run into. Printed it, printed it again with correct settings ;). And replaced it.

And with that, my tarantula can print flex filament (TPE88 to be precise) at 50mm/sec at 0.2mm layer height, 0.4mm nozzle, Example print:

100mm/sec at 0.1mm layer height with 0.4 nozzle works too but makes not much sense as the higher speed adds too much artifacts and 100mm/sec at 0.2mm is beyond what the hotend of the tarantula can melt, so i did not try that. Also it seems retracts work fine though were disabled in the example shown above, the 100mm/sec test i did had retracts enabled.

The modified RSE2 extruder is available on thingiverse, if you want to print it. It works with MK8 drive gears as well as UM2 Knurled drive gears. The MK8 seems to work better of the 2 in terms of extrusion error per backpressure. and both provide 40-50% more force than the original tevo tarantula one with the same stepper and driver. Some cheap ones from aliexpress:

Filed under: 3D printer — Michael @ 1:28
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