Posts Tagged ‘electronics’

Paper backed Soundmirror ‘magnetic ribbon’ – early domestic magnetic tape recorders

Monday, September 30th, 2013

The oldest tape we have received at the Great Bear is a spool of paper backed magnetic tape, c.1948-1950. Its pretty rare to be sent paper backed tape, and we have been on a bit of adventure trying to find more about its history. On our trail we found a tale of war, economics, industry and invention as we chased the story of the ‘magnetic ribbon’.

DSC02417 Paper backed Soundmirror magnetic ribbon   early domestic magnetic tape recorders

The first thing to recount is how the development of magnetic tape in the 1930s and 1940s is enmeshed with events in the Second World War. The Germans were pioneers of magnetic tape, and in 1935 AEG demonstrated the Magnetophon, the first ever tape recorder. The Germans continued to develop magnetic tape, but as the 1930s wore on and war declared, the fruits of technological invention were not widely shared – establishing sophisticated telecommunication systems was essential for the ‘war effort’ on both sides.

Towards the end of the war when the Allies liberated the towns and cities of Europe, they liberated its magnetic tape recording equipment too. Don Rushin writes in ‘The Magic of Magnetic Tape.’

‘By late 1944, the World War II Allies were aware of the magnetic recorder developed by German engineers, a recorder that used an iron-powder-coated paper tape, which achieved much better sound quality that was possible with phonograph discs. A young Signal Corps technician, Jack Mullin, became part of a scavenging team assigned to follow the retreating German army and to pick up items of electronic interest. He found parts of recorders used in the field, two working tape recorders and a library of tapes in the studios of Radio Frankfurt in Bad Bauheim.’

In the United States in WW2, significant resources were used to develop magnetic tape. ‘With money no object and the necessity of adequate recording devices for the military, developments moved at a brisker pace’, writes Mark Mooney.

vinAd46Brush1 Paper backed Soundmirror magnetic ribbon   early domestic magnetic tape recorders

This where our paper tape comes into the equation, courtesy of Polish-born inventor Semi J. Begun. Begun began working for the Brush Development Company in 1938, who were one of the companies contracted to develop magnetic tape for the US Navy during the war. In his position at Brush Begun invented the ‘Sound Mirror.’ Developed in 1939-1940 but released on the market in 1946, it was the first magnetic tape recorder to be sold commercially in the US post WW2.

As the post-war rush to capitalise on an emerging consumer market gathered apace, companies such as 3M developed their own magnetic tapes. Paper backed magnetic tape was superseded toward the end of the 1940s by plastic tape, making a short but significant appearance in the history of recording media.

This however is a story of magnetic tape in the US, and our tape was recorded in England, so the mystery of the paper tape has not been solved. Around the rim of the rusted spool it states that it is ‘Licensed by the Brush Development Co U.S.A’, ‘Made in England’, ‘Patents Pending’ and ‘Therimonic Products Ltd.’

Therimonic were the British company who acquired the license to build the Soundmirror in 1948. Barry M Jones, who has collected a wider history of the British tape recorder, home studio and studio recording industries writes, ‘[Soundmirror] was the first British-built domestic tape-recorder, whereas the first British built-and-designed tape recorder was the Wright & Weaire, which appeared a few weeks later. Production began in autumn 1948 but the quality of the paper tape meant it shedded oxide too readily and clogged the heads!’

Production of the Soundmirrors continued to late 1954 so it is possible to date the tape as being recorded some time between 1948 and 1958. The weight of the spool and the tape is surprisingly heavy, the tape incredibly fragile, marking its passage through time with signs of corrosion and wear. It is a beautiful object, as many of the tapes we get are, that is entwined with the social histories of media, invention, economy and everyday life.

How sustainable is digitisation?

Monday, July 8th, 2013

Often when we think about the reasons to digitise magnetic tape collections we are considering the future. We digitise to make material accessible so it can be used again, or to preserve it so subsequent generations can benefit or learn from it. But how sustainable is digitisation and digital technology? What is the ecological impact of the widespread and breathtakingly fast adoption of digital technologies since the late 1990s?

At an everyday, consumer level, the use of digital technologies comes with real human and environmental costs, as Professor Toby Miller and Professor Richard Maxwell demonstrate in a recent article in The Guardian. They argue that the very metaphors we use to describe digital media – ‘virtual,’ ‘cloud’, ‘streams’ and ‘mobiles’ – dangerously obscure the fact they come from materials, such as the minerals Tatalun, Tungsten, Tin and Gold, and cover up the exploitative labour conditions, and war torn situations from which they are extracted:

‘Suggestions that we live in a dematerialised world are not only exaggerated; they are doing more harm than good. One person’s cloud is another’s pollution, and one person’s mobile is another’s enslavement. From electronic waste to conflict minerals, the new media leave an indelible mark on bodies and the Earth they inhabit.’

The extent of violence and exploitation that lie at the end of the digital supply chain is hardly a secret. At a consumer level there seems to be very little resistance to the use of mobile digital devices, probably because our very social existence is dependent upon them in a culture where media is pervasive. It is not easy to opt out, and what would you do if you did?

e waste How sustainable is digitisation?

As heavy users of digital technologies we walk with our heads in the clouds, so to speak, unable to access the wider environmental impact of our actions. This impact is intensified by the pressure to continually upgrade our devices, as Dr Chris Priest writes,

‘the regularity with which you replace a device becomes more important in determining the overall footprint of the device. If we take a hypothetical device with a 50% use footprint, and replace it after two years rather than three, then it will increase our overall footprint by 25%. Of course, new devices might be becoming increasingly efficient and this could offset the increase to some extent. Though even if the new device used no power, it could not offset it completely.’

Yet these are speculations not empirical fact. It is hard to know concretely what the environmental consequences of becoming immediate adopters of the latest (fastest, smallest, bestest) digital technologies are. One thing is certain, new goods will appear and people will be told they can’t live without them. This is how an economy driven by innovation works.

Thinking about the uptake of digital technologies at an institutional level, it is clear that within a technological climate pre-disposed to the production of ‘digital waste’ and obsolescence, the mismanagement of energy resources in order to keep digital data ‘alive’ (that is useable, accessible) is a real possibility. One only need turn to the financial and technological waste produced from the BBC’s Digital Media Initiative (DMI) to confirm that the creation of technical systems devised to manage large digital archives are not moving at the same relentless speed as the neoliberal market.

Which begs the question: can there be an ecological solution to the problem of digitisation, and the use of digital technologies in an innovation/ obsolescence economy? Can digitisation ever be energy efficient, non-exploitative and flexible enough to cope with the technological changes that will inevitably happen? What would a sustainable and ethical approach to digital information management look like?

As our world gets increasingly networked these are pressing questions effecting everyone. And clearly understanding the wider impact of the use of technology on people and the earth is a serious issue, usually forgotten when scrolling through data feeds in a voracious, but often distracted, manner. These are admittedly big questions and we welcome comments, links and ideas on how to answer them.

As keen hoarders of mechanical waste from the analogue era who are passionate about making data accessible in digital form, we are contributing to a world that places unprecedented value on technological information.

Need this, however, always be at the expense of people and the world we share as currently it seems to be?

 

Repairing obsolete media – remembering how to fix things

Monday, June 17th, 2013

A recent news report on the BBC website about recycling and repairing ‘old’ technology resonates strongly with the work of Great Bear.

The story focused on the work of Restart Project, a charity organisation who are encouraging positive behavioural change by empowering people to use their electronics for longer. Their website states,

the time has come to move beyond the culture of incessant electronics upgrades and defeatism in the face of technical problems. We are preparing the ground for a future economy of maintenance and repair by reskilling, supporting repair entrepreneurs, and helping people of all walks of life to be more resilient.

We are all familiar with the pressure to adopt new technologies and throw away the old, but what are the consequences of living in such a disposable culture? The BBC report describes how ‘in developed nations people have lost the will to fix broken gadgets. A combination of convenience and cultural pressure leads people to buy new rather than repair.’

These tendencies have been theorised by French philosopher of technology Bernard Stiegler as the loss of knowledge of how to live (savoir-vivre). Here people lose not only basic skills (such as how to repair a broken electronic device), but are also increasingly reliant on the market apparatus to provide for them (for example, the latest new product when the ‘old’ one no longer works).

A lot of the work of Great Bear revolves around repairing consumer electronics from bygone eras. Our desks are awash with soldering irons, hot air rework stations, circuit boards, capacitors, automatic wire strippers and a whole host of other tools.

teac a3440 circuit board closeup Repairing obsolete media   remembering how to fix things

We have bookshelves full of operating manuals. These can help us navigate the machinery in the absence of a skilled engineer who has been trained how to fix a MII, U-Matic or D3 tape machine.

As providers of a digitisation service we know that maintaining obsolete machines appropriate to the transfer is the only way we can access tape-based media. But the knowledge and skills of how to do so are rapidly disappearing – unless of course they are actively remembered through practice.

The Restart Project offers a community-orientated counterpoint to the erosion of skills and knowledge tacitly promoted by the current consumer culture. Promoting values of maintenance and repair opens up the possibility for sustainable, rather than throwaway, uses of technology.

Even if the Restart Project doesn’t catch on as widely as it deserves to, Great Bear will continue to collect, maintain and repair old equipment until the very last tape head on earth is worn down.

Sony PCM 7030 DAT repair

Friday, October 14th, 2011

sony pcm 7030 Sony PCM 7030 DAT repair

We have several of these large, wonderful machines. It’s not often we need or want to get involved in DAT repair as generally they are not easy to service machines and many key transport parts are becoming unavailable. The Sony 7030 DAT though has been designed with easy servicing in mind. There’s alot of room in these things and each section is clearly marked and separated into distinct boards much like Sony Broadcast video machines.

These are timecode DAT machines and were once common in video post production houses and the more well funded recording studios. The problem with some of this well built kit though is exactly that it works too well and gets left on for long periods through it’s life and this can take a toll on certain components, especially electrolytic capacitors. Heat builds up in electronic circuits, especially in switch mode power supplies that larger broadcast items often use. Capacitors have a rated life at 85°C or 105°C at several thousand hours. With hotter environments, substandard parts and long operating hours these capacitors can soon outlive their original design life.

Our 7030 DAT had started behaving oddly and at first the display would flash on and off after a short while powered on. Another machine would power up for 30 secs then just die. Before delving into the enormous service volumes it’s always worth replacing the Switch Mode Power Supplies (SMPS). These like many broadcast machines use supplies that are sometimes generic made by other companies and which can be bought at Farnell or RS. We did it the harder was and desoldered all the old capacitors in the power supply and replaced these with high quality low ESR Panasonic ones which should give us another 6000 hours of running time. So far this machine has worked perfectly although you do need good soldering and desoldering technique on these boards. A powered air desoldering station is a good idea, much, much better than a hand solder pump.

Video time base corrector self destructing mains socket

Friday, August 27th, 2010

cel tetra power filter 477x1024 Video time base corrector self destructing mains socket

We have several time base correctors and frame synchronisers at our disposal. One recent addition is a new old stock (NOS) CEL Tetra. This is an early 1990’s motion adaptive Standards Converter for PAL, SECAM, NTSC 3.58 and NTSC 4.43 systems. A very flexible unit with composite, Y/C (S-Video), umatic DUB High Band/Low Band and component inputs and outputs.

Out unit still has it’s shipping caps over the BNC sockets and looks unused but after 5 minutes of power a cloud of white smoke billowed out of the cooling fan accompanied by a pungent smell. The Shaffner EMI mains filter had a nasty, sticky brown residue leaky out and all around the back of it. This is the second TBC that I’ve had this happen to. I’d assumed these units get left on for long periods when used in broadcast applications which would hasten their demise. According to their website, the mean time between failures (MTBF) of their recent products is around 2,000,000 hours! Our CEL TBC doesn’t look like it’s done more than 30 minutes so maybe there’s been some dodgy electrolytic fluid in these units just like the motherboard capacitor problems between 2000 and 2003.

Switch mode power supply (SMPSU) repair in For-a FA-310P time base corrector

Thursday, August 5th, 2010

for fa 310p power supply 614x1024 Switch mode power supply (SMPSU) repair in For a FA 310P time base corrector

We use time base correctors and frame synchronizers all the time in the transfer and digitising of analogue video tape.

One of our more flexible and high quality units had recently developed an annoying and very obvious fault on it’s video outputs. While the unit was working there were faint but distinct horizontal lines on the video. This phenomenon is often called a hum bar and can be caused by ground loops.

In this case we isolated the unit from the rest of our installation and using a separate power point the problem was still there. Looking at the unit itself it is a very deep and heavy 1U case with two 40mm cooling fans at the rear corners. It is quite old too and being designed for continuous studio use is likely to get hot and have been on for very long periods.

The video fault appeared to be AC ripple ‘riding’ on the DC power. It was time to look at the electrolytic capacitors in the power supply.

Although I could have tested each one, all these caps were old and only rated for 3000 hrs at 85 celcius so they all had to go! Here’s a list of them:

The only one hard to find was the large 400v dump one. Most units now are thinner and taller but eBay came to rescue here.

This shotgun approach worked beautifully and the fault had gone. While tracing the exact fault is always the best way, capacitor often get a hard life and will not last indefinitely, especially in switch mode power supplies.

Video Tape Transfer, Copy to DVD, DV or uncompressed AVI

Thursday, April 2nd, 2009

Over the last 12 months we’ve seen this side of our business grow and adapt to the range of transfer needs that individuals, businesses and media creation organisations have.

We are able to support a wide range analogue and digital, consumer and professional video formats from the late 1970’s onwards such as: Betamax, VHS, SVHS, VHS-C, Video 2000, 8mm, Hi8, uMatic, Betacam, miniDV, DVCAM, etc.

We offer straight video transfer to DVD and a higher quality transfer service to DV or  uncompressed AVI which can then be supplied on hard drive, edited, encoded to a very high quality DVD or supplied on digital tape.

We pride ourself on our positive, friendly service and are happy to give advice over the phone or by email. When you call us you won’t be stuck in a voicemail system or told we’re an internet company so don’t like speaking on the phone!

Feel free to contact us by phone or email.

Focusrite Saffire LE SPDIF problems

Monday, February 23rd, 2009
focusrite saffire le Focusrite Saffire LE SPDIF problems

Focusrite Saffire LE

I’ve owned one of these Saffire LE firewire interfaces for a few years now and it’s very useful as a backup to my RME interfaces especially when I need to record and transfer audio at another location as it’s small, light and portable. It’s a very good sounding interface and  it even is reported to work under Linux which I’ve tried but unfortunately not with Audacity as this that doesn’t use the Jack server.

I’ve had an ongoing issue with the SPDIF inputs though. Under Windows XP and MacOS X it refuses to record more than a few mninutes if locked to another digital unit such as DAT machine and the Saffire software reports the firewire interface has lost it’s connection. This has rendered all SPDIF transfers impossible to do correctly.

The support at Focusrite is very good, you can actually speak to someone! We tried using an external power supply unit (PSU), different firewire cables, checking the type of firewire interface in the Windows machine and upgrading the firmware under MacOS X but all to no avail. This is a repeatable issue under several different computers and OS’s.

service manuals on eBay

Friday, December 12th, 2008

Are you fed up of sifting through all the, often Public Domain, PDF Service Manuals listed on eBay?

Apart from the fact that as many of them are public domain they are freely available to download they get in my way on searches for interesting old stuff. Take a search on Studer tonight, over 500 results and over 400 of these for service manuals or Studer documents for their reel to reel and other audio products from the past all of which can be downloaded from Studer’s public FTP server!!

I know some may call it legitimate business but I feel sorry for anyone who’s paid over a tenner (£10 GBP) for one even if it’s supplied on a nice shiny CDR or printed on laser paper and bound in a plastic wallet!

So, for everyone who likes to understand how things work and fix their own old equipment and not just throw it away, here’s some of my ‘favourite’ manuals that aren’t so easily available on the internet – for FREE!:

Tascam 112 Mk 1 Service Manual

Tascam 238 8 track Service Manual

Tascam DA88 DTRS 8 track service manual

Teac C-3x Service Manual

Nakamichi 610 Preamp Service Manual

Arcam Delta 70 CD player Service Manual

Philips CD104 Service Manual

NAD 3020 Service Manual


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