alt Hacker NewsLooks like he made his own service manual for this piece of gear and it has the manufacturer's logo on it without their consent.
Which he prepared for the client in decent presentation quality.
One of the most admirable things to do, above and beyond most repair professionals, looks like Mark really is a cut above and it shows.
The top instrument companies have always recognized the advantage of partnering with the rare individual who can service their complex and unique products, and have been the most willing to provide schematics and discounted parts in order to make as many into authorized service centers as possible. To enable field calibration and service, or bench work without having to send their own people or ship the unit back to the main repair depot.
The lesser outfits, not so much.
If you've got money-making instruments to sell, you really don't want to work against someone who has the talent to fix defects without even having any factory documentation. That's hard to come by, they could be your best ally. Imagine what could happen with full factory support.
And Mark prepared his own documentation! How much more respectable can you get?
Posting it on Youtube is the only real mistake, unfortunate but true.
Obviously, Youtube is not a respectable enough place, oh well, who knew?
From the commentary it does look like the circuits are not more innovative than the "generic" guidelines published by the component manufacturers to encourage engineers to adopt their semiconductors for various intended purposes.
When these analog devices were first emerging, some of these data sheets were widely published back when some of the example circuits were still under patent. There was every expectation that if you copied one of them, you would have to license it before you could legitimately include it with your own product. For these preamp components, patents have all expired now so that's not a consideration any more. However it's possible that somebody 30 or 40 years ago might have drawn up a PCB of a completely generic circuit that exactly conforms to an example public-domain schematic, no longer under patent by decades, but that pattern on the PCB could easily still be under copyright for decades to come.
You create your own original artwork, you own it, even if the circuit is exactly the same.
Thus I would say the patterns on the PCBs are only legitimate to reproduce in much less than their entirety, like passages from a book. That could be a pitfall, but I don't think more than a few relevant excerpts were casually shown in the video.
Replies
Xe re-created xyr own formal full design document for the product, showing the precise PCB shapes and the positions of the components, holes, and ports. Xe boasted about doing so, and published the document, leafing through it page by page and pointing out in a couple of places where the diagrams matched the physical product, in a YouTube video.
To understand this, one has to not miss (as so many unfortunately have) where Louis Rossman read out a part of an e-mail to MendItMark where it was stated by Tom Evans Audio Design that these are registered designs.
There is a third right in U.K. intellectual property law, a third right that the Copyright, Designs, and Patent Act 1988 grants in addition to copyrights and patents. It's there in the Act title: design right.
Design right grants exclusive right to its owner to make "a design document recording the design" and subsists in "the shape or configuration (whether internal or external) of the whole or part of an article".
* https://www.legislation.gov.uk/ukpga/1988/48/part/III
Copyright and patent are beside the point. Tom Evans went after MendItMark on design right grounds, which is not really that surprising given that it is Tom Evans Audio Design and the WWW blurb at https://www.audiodesign.co.uk/ explains that Tom Evans does design work.
There are hundreds of registered printed circuit board designs, and audio amplifier designs, that one can find on DesignView (the EUIPO search tool), to compare and thus see exactly how MendItMark's ring-bound 12 page document records the design of the product; and that is just registered designs. (Although Tom Evans claimed that these are registered, xe would still have design right even if they were not, as xe gains the right from having manufactured products to xyr design.)
The sad thing is that MendItMark would have been able to lambast the poor design with total impunity if xe hadn't done what §226 of the CDPA names primary infringement of design right . As it stands, Tom Evans seems to have a very strong leg to stand on, from the black and white of the statute.
Whilst MendItMark doesn't even have the possibility of claiming that xe did this for educational reasons, as xe not only monetized the video (which makes it a publication for commercial purposes) xe stated in the video right after showing the document that this stuff was part of xyr £400 a pop (currently discounted to £250 as I type this) training course.
Also note that YouTube's terms and conditions don't say merely not to infringe copyright. They say not to infringe other people's intellectual property rights, and design right is such a property right in the U.K., where both Tom Evans (1 bloke in Wales) and MendItMark (1 bloke in England) are located.
The only remotely creative aspect of the preamp was the use of discrete voltage regulators for almost every component in the audio path. It has a comical number of voltage regulator ICs.