repair snapped DAT

October 19th, 2011

D120 broken DAT tape

We often get sent Digital Audio Tapes or DAT’s for transfer to .WAV computer files. As these recordings are already digital or ‘born digital’ the process should be straightforward. Our audio interface cards accept the SPDIF or AES digital audio stream from the DAT machine and record this as a WAV or BWAV file. This file can then be burnt as a CD or delivered digitally on a hard drive or removable media.

The big problems though come with the tape that these digital recordings are made on. The tape is only 3.81 mm wide and moves at a very slow 8.15 mm/sec. The tape is also very thin at 13 microns. The recording system and transport used is helical scan just like in video recording but with the very slow tape speed and small tape dimensions any defects or problems with the tape can result in many errors which may not be correctable by the error correcting system of the DAT machine.

One problem we’re starting to see more and more are tapes that snap. The tape pictured above was a D120 which was never recommended by the DAT machine manufacturers but was still often used for it’s extended recording time. This tape snapped without warning a quarter of the way through the recording. There were no outward signs or potential problems just a sudden clean break on a diagonal.

snapped dat tape

To recover this tape it could have been spliced with splicing tape of the correct width like in analogue recording but there is a high risk if not done perfectly of unrepairable damage to heads on the drum. Even with this type of repair some of the material would have been lost. A safer solution is to rehouse each spool in another shell this lets you recover as much as possible from the tape without the risk of head damage.

Whichever solution you decide the DAT shell must be disassembled. A small crosshead screwdriver needs to be used to remove all the case screws. There are two hidden ones, accessed by sliding part of the cassette shell down:

disassembling dat shell

You can now carefully lift both halves of the DAT shell apart, making a note of the tape path inside the shell. Be careful not to touch the tape with your bare skin as fingermarks and grease can cause head to tape contact problems and audio errors and dropouts.

 

 

 

Sony PCM 7030 DAT repair

October 14th, 2011

Sony PCM 7030 DAT machine

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.

Tape baking of unreleased Shoes for Industry studio master

October 5th, 2011

Shoes For Industry unreleased tape label

In amongst a batch of very mouldy quarter inch master tapes we were recently asked to look at was this unreleased recording by Shoes for Industry, the Bristol band on Fried Egg Records.

Like much late 1970’s and 80’s studio recordings, this was recorded on Ampex branded tape that suffers badly from binder hydrolysis or ‘sticky shed syndrome’ that must be addressed before the tape can be successfully played and digitised. This was in addition to the mould growth that was evident on the tape pack edges, and cardboard box. Storage in damp conditions and high humidity causes this type of mould and increases the breakdown of magnetic tape generally, sometimes to the point where de-lamination occurs, that is, the binder breaks away from the polyester structure of the tape. When this happens, which is luckily quite rarely, the magnetic information is damaged and mostly lost beyond repair.

Thankfully this tape, whilst it looked in poor condition was relatively straightforward to restore but time consuming. Careful hand winding, and mould cleaning is necessary as is awareness of the potential health effects of some mould spores so good ventilation and protective masks are necessary.

 

Tape mould cleaned and removed. Rare lost masters recovered and preserved for Druidcrest Ltd

September 30th, 2011

Punk Rock Classics tape label

We have recently worked on probably the worst looking tapes but with some of the best sounding music recordings we’ve seen for a while! A batch of 10.5″ NAB studio masters had bad tape mould growth.

Andy Leighton, owner of Bolex Brothers and music publisher of the Rocky Horror Show, found a batch of studio masters on quarter inch tape that had been growing mould for some of them over 30 years. All of these recordings had been made at the renowned Sound and Recording Mobile studios better known as SARM, later creative home of Trevor Horn.

First ever recording at SARM studios

 

Among these tapes was the first ever recording made at SARM in 1972 by Richard o’Brien, writer of the Rocky Horror Show, in addition to rare tracks by artists such as Kimi and Ritz.

When the tape mould was finally cleaned from the tapes and some of them baked for binder hydrolysis the quality of the recordings was very high and testament to the high quality available from analogue recording and even though tape can be vulnerable to physical problems it is also robust. If these had been tape based digital recordings, in the same condition, I doubt we’d have been able to achieve the same results.

Quarter inch reel to reel tape transfer of Jack Hawkins band archive

July 8th, 2011

We were contacted recently by Jack Hawkins, the renowned arranger and band leader to consult on and digitize personal quarter inch open reel recordings of his band.

In case you don’t know, The Jack Hawkins band are probably best known for their performance of the track 30-60-90 made famous in a club sequence in the 1971 film Get Carter starring Michael Caine.

Replace pinch roller on Sonifex NAB Cartridge machine

June 2nd, 2011

Once a common sight in Radio stations around the world, the NAB Cartridge machine or Fidelipac was used for short jingles and announcements, sometimes even for longer recordings. Using a similar sized cartridge to a domestic 8 track machine the NAB cartridge was different in that the pinch roller was not in the cartridge but would hinge up in the player and hold the tape against the capstan. Running at 7.5 inches per second (ips) compared to 3.75 ips in domestic cart machines the recording and reproduction quality good be very good but it was the ease of use and cueing ability offered by these machines that made them so useful in broadcasting.

We have Sonifex cart machines that while very well built do have rubber parts that will degrade over time and reduce the transport performance. Luckily we have some of the last remaining stock of new pinch rollers, motors and capstan drive belts.

The pinch roller in one of our machines had become quite hard and the rubber shiney over time. A pinch roller in this state may not hold the tape as securely and could also have flat spots both leading to increased wow and flutter and poor tape handling. These pinch rollers also have high quality cartridge bearings pressed into their shell. Over time these loose their lubrication, wear, become rough feeling and will also add to poor tape handling.

Older, fragile and valuable tape must be handled and used carefully. A ‘chewed’ tape caused by a poorly maintained tape transport in any tape machine, audio or video is a disaster and hard to recover from perfectly.

Sonifex NAB cart pinch rollers

Both halves of the cart machine case need to be removed to easily change the pinch roller. While the access is good and the machine, in this case a Sonifex microHS, had been designed for easy servicing the pinch roller is still a little fiddly to get to so I removed the transport from the main chassis.

Sonifex NAB cart machine microhs transport removed

To remove the pinch roller a small slightly hidden C clip must be removed you can see in the image above the slot machined into the roller shaft where it sits and holds the roller. This is hard to remove as the plastic bush on top of the roller stops you getting a small screwdriver in. I managed to remove the C clip with some fine circlip pliers. Be careful not to loose the clip if you don’t have spares, they fly away very easily!

Now the new roller can be placed on the shaft. It’s a good idea once all the transport is out to give everything a good clean with IPA.

Sonifex microHS new pinch roller

On this machine, the castan drive belt was quite slack so a new one was fitted, which is easy now the transport is removed. First though the capstan flywheel and motor pulley were cleaned of all the old rubber belt residue that tends to accumulate over time.

Sonifex NAB cart machine capstan flywheel

The last thing to do is check the pinch roller pressure. This is important to as to high or too low will increase wow and flutter, increase wear to the bearings and capstan surface and give poor tape handling. Due to the design of these NAB cart machines, the pinch pressure needs to be checked with a special cartridge. The pinch pressure is then adjusted from a screw pot on the top PCB seen outlined below in green.

NAB cartridge pinch pressure adjustment

That’s it, time to play carts again.

‘Celebrate What?’ St Pauls Carnival 1968, Bristol

May 27th, 2011

A documentary we transferred and created DVD access copies for its director recently. He only had a VHS copy of the 8mm original unfortunately but it’s still a great piece of history about St Pauls, the St Pauls Carnival and Bristol.

If anyone can recognise themselves or anyone else, please contact the director, Colin Thomas by email, ctbr03509@blueyonder.co.uk

Umatic transfer and video preservation of Bristol reggae band Black Roots

April 13th, 2011

2 u-matic video tapes were discovered of a Black Roots live performance in Bristol in the 1980’s. We were able to restore, digitise and make the umatic transfer of this recording as a high quality, uncompressed Quicktime file then encode and author a DVD for future release by Bristol Archive Records.

Some information supplied by the label:

Black Roots were Bristol’s premier Reggae band throughout the eighties and having gone their separate ways in the nineties they reformed last year and will be rekindling the magic with an intimate hometown gig at the Fleece on Friday September 9th, the show coincides with the release of “Black Roots – The Reggae Singles Anthology”, released on Bristol Archive Records in collaboration with Nubian Records, this release showcases all of the band’s singles released during their first decade and as an extra bonus the CD issue comes coupled with a DVD of the band’s 1986 video release “Celebration” recorded at the long gone Studio nightclub in Bristol. This show will be something special and likely sell out so book your tickets early and don’t miss out.

www.thefleece.co.uk

 

 

Kevin Mabbutt hat-trick against Manchester United EIAJ video reel restored and digitised

March 8th, 2011

We were very excited recently when Chris Bradfield from Soundscommercial uncovered a previously unseen batch of EIAJ half inch reel to reel video tapes. In the process of looking for 1976 footage for their event, Sprit of 76, we uncovered many other gems. One of these goals was the famous hat-trick scored by Kevin Mabbutt against Manchester United at Old Trafford in 1978. Mabbutt is one of only two players in Football League history even to have done this and this footage was never recorded anywhere else!

Unfortunately this large batch of valuable recordings had been stored in damp, unheated conditions and had suffered. The tape had deteriorated in several ways.

  • Mould growth was evident on some tapes
  • The oldest tapes from the early 1970’s were shedding oxide severely and had little lubrication left in the binder.
  • Binder hydrolysis, often called sticky shed was evident on other tapes.

Each issue needed a different process to treat the tape. The common assumption that ‘tape baking‘ will restore all unplayable tape is not true. It is just one solution to one of these issues and can cause more problems if used incorrectly. Deteriorated video tape is much less forgiving than audio tape when attempting transfer and must always be handled and processed with extreme care. Crinkled, curled, edge damaged tapes are next to impossible to restore back to their original condition and it’s common that more damage can occur when owners are desperate to transfer footage.

We were able to restore all the tapes to a playable condition and make uncompressed quicktime files of these.

Below is a clip from a later recording. We are not able, unfortunately, to show the Kevin Mabbutt clip yet.

NTSC umatic transfer of The Members – Solitary Confinement

February 28th, 2011


Unseen to 32 years, although there could possibly be other tapes in the vaults at Abbey Road.
This ntsc umatic transfer to uncompressed quicktime files was a damaged tape that at some point in it’s life had been ‘eaten’ by a greedy u-matic machine! The tape shell also had some plastic debris inside that needed removing before it was safe to attempt loading and migration.

reel to reel tape transfer of rim drive or capstan free recordings

February 22nd, 2011

The capstan drive tape recorder is (or was) very common and was used in a huge range of cassette tape audio, video and open reel machines from cheap domestic to very expensive broadcast tape machines.

Occasionally we receive quarter inch tapes, always be on small 3 inch spools, that reproduce on our capstan drive machines with terrible speed variation. They start off very fast then gradually slow down over the duration of the recording to around normal speed.

These reels must have been recorded on rim drive machines. These type of open reel tape recorders didn’t use a capstan and pinch roller to save space and more often cost. As there is no capstan, as the supply reel gets smaller the tape recording speed increases. When replayed on a rim drive machine the speed, while not likely to be ‘Studer stable’ will be pretty stable and the recording sound OK.

It’s not feasible or desirable for us to own unlimited machines of all types due to the time to service and repair them, find parts and storage space therefore we use a small range of carefully picked high quality tape machines that with care can replay most tapes, speeds and track formats. This is the problem with rim drive recordings and an analogue or digital solution must be found.

The tapes we received were 15 reels of family recordings from the Welsh Valleys. Others apparently had tried to transfer these tapes but gave up finding no material. This was easily solved as the tapes were wound the opposite way to normal so the oxide was facing out not in. This is the same as in audio cassettes. The original tape machine must have had it’s heads in a similar position to a cassette machine.

Major audio and video archive tape transfer and H264, MP4 video encoding for Archive for Mathematical Sciences and Philosophy

September 3rd, 2010

We’re very happy to be working with Mike Wright and the Archive for Mathematical Sciences and Philosophy on a large scale and ongoing transfer, restoration and online management programme.

akloster tape 2a Download whole video to your computer

Video time base corrector self destructing mains socket

August 27th, 2010

Filtered mains socket self destructs in CEL TBC

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.

tape repair and restoration

August 27th, 2010

Unspooled cassette tape in a bag as received by us

We often receive enquiries about audio and video tape that is not in the best condition having been stored in humid conditions, suffering from binder hydrolysis (sticky shed) or not wound on it’s reel well but we were surprised when we received this tape recently.

It literally is a bag of tape! It is a cassette tape that had at some point become unspooled, probably when the cassette shell was opened for a repair. We can and did restore the tape by respooling and reshelling before playing on one of our Nakamichi dual capstan cassette decks.

This is a time consuming job though as thin tape twists, turns and crinkles up very easily needing careful tension, customised winding systems and protection from contaminants such as dust, grease, etc that could cause more damage to an already compromised recording.

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

August 5th, 2010

For-a FA310P Switch Mode Power Supply

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.


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