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.

Audio data recovery from external USB drive using ddrescue

June 30th, 2010

High resolution audio and video digital tape conversions can use large amounts of computer storage. 8 bit uncompressed Standard Definition (SD) PAL video runs at 70 GB per hour and 24 bit 96 kHz audio files at 2 GB per hour.

As a result of this many of our analogue to digital tape transfers require the use of external storage, usually USB 2.0 portable hard drives, to supply the copied digital transfers back to the customer. Some drives supplied by customers have not been of great quality and not designed to be sent about in the post. One such drive we had recently, a Sony Vaio branded 2.5″ USB drive wouldn’t copy certain directories of important files with the Mac OS Finder or the Windows Explorer. While most of the drive copied this certain folder always resulted in a crashed computer!

Thanks to GNU/Linux we have a bit more power and information at our disposal about hard drives and IDE or USB interfaces. It’s always best practice to copy as much information from the drive or mirror it before attempting any other types of data recovery or file system repair. Using the standard dd

Powerful tape conversion tools using SoX, LAME and Bash Scripting

June 29th, 2010

SoX running in the MacOS X Leopard Terminal.app

One of our recent and ongoing jobs is a very large, over 2000, NAB 10.5 inch reel to reel archive of quarter inch professional tape recordings.

To fit into the budget but maintain quality we needed to find a way to streamline our workflow in converting the high resolution 24 bit 96 Khz master .wav  files to CD quality (16 bit / 44 Khz) and MP3 (320 kbps) audio files.

Typically this would be done manually with 2 track audio software such as Audacity, Peak Audio Tools, Wavelab, etc with a Graphic User Interface (GUI). For such a large amount of individual files this is time consuming, expensive and unnecessary. While many audio editors have batch processing tools, Amadeus Pro being one of our favourites, they are still not as flexible as combining command line tools with a Bash script.

SoX is a powerful command line audio tool that can be used to edit, convert, process, record and play a wide range of digital audio files. It also has a very high quality resampling algorithm which we are using here.

Once the tape reels have been digitised they are split into individual .wav files which are then renamed with artist and track details using a php script that accesses a .csv file. These 24/96 resolution files are then converted to lower, CD resolution using SoX and to 320 kb/s MP3’s using LAME. The script also uses sed, the stream editor, to add the text _16_44.wav or _mp3.mp3 to the filename for ease of identification. The script finds all files with the suffix _24_96.wav in all the subdirectories of it’s working directory and processes these.

At the moment this script is running under Mac OS X 10.5.8 using the MacPorts project but will, in time, be moved to one of our Apple G4 servers running the PowerPC version of Debian GNU/Linux 5.05 ‘Lenny’.

HTC Desire in the toilet

June 1st, 2010

HTC Desire android mobile smart phone

Not our normal type of post but the new HTC Desire Android smart phone has been so useful with it’s open source applications, fast speed and wifi that I couldn’t believe I’d just put the phone in my shirt pocket and leant over the toilet!

Panicking, I fished it out and messed about trying to shut it down, when I should have just whipped the back off and the battery out. I did manage to get the battery out pretty quickly but not before I’d seen the screen start to make weird colours and odd lines. The thought of buying a new phone at full price was too much so I pulled out a handy bottle of Isopropyl alcohol (IPA) we use for cleaning tape and video record and repro heads. This is 99% pure IPA, not cheaper ‘rubbing alcohol’ that is often 70% IPA with 30% water. You really don’t want to make your phone any worse!

When I’d calmed down a bit I checked the moisture pads that show if the phone’s had water contact. These had gone pink confirming the toilet dunking so no warranty repairs here! Having little to lose I removed the 4 small torx head screws and the two even smaller crossheads screws under the rear cover. Two of the Torx screws have ‘void’ stickers over them so again once you undo them you’ve lost your warranty!

Now the bottom cover over the USB connecter can come up as can the inner cover which will reveal the wifi / bluetooth aerials. I didn’t remove the screen but ‘carefully’ poured IPA all over the bits that smelt of wee!

99% pure IPA will evaporate very quickly but any residual moisture should go before you can think about putting the battery and other cards back in. Many online sources recommend uncooked rice to absorb moisture but purpose made desiccants are best. I used several silica gel sachets in a freezer bag with the disassembled phone and left this overnight.

Thankfully this all worked, the phone starts, the screen works it’s alive!

The key points when you have this kind of phone disaster are:

  1. Get the phone out of the water / wee
  2. Get the battery out as soon as possible
  3. Remove all the SIM / memory cards
  4. Shake or carefully pat dry as much liquid as you can
  5. Any liquid contaminant that isn’t pure water and contains sugars or salts must be cleaned off
  6. If you try IPA make sure it’s high purity 99% is best

Finally, we’re tape transfer specialists not phone repair specialists so I offer no guarantee with all this but it did work for me.

Replace Tascam BR 20 Capstan Belt

May 10th, 2010

We have two of these excellent machines in addition to our Sony APR 5003 and Studer A80’s. The Tascam BR-20 was Tascam’s last and top of the range 1/4 inch reel to reel tape machine and available in two track stereo and stereo with centre timecode option.

The capstan drive in the BR20 is belt driven by a wide belt. Both belts in our machines looked OK but we’ve replaced all roller bearings, belts and pinch rollers in both of our machines anyway as a matter of course. These parts are still available from Teac UK via Acoustic Services on 01-844-347600.

Below is a simple explanation of how to change the capstan belt.

Tascam / Teac BR 20 rear panel removed

  1. Unplug machine from mains power and move to a strong stable base.
  2. Remove cross head screws from the rear panel and lift plate off. Depending on the type of plug in your country you may not be able to remove it completely.
  3. You’ll now be able to see the capstan motor and it’s control board attached to it.
  4. Remove the 4 cross head screws and gently lift the analogue audio output board away from the machine as in the picture above.
  5. We now need to remove the whole capstan motor assembly with the control board still attached. Remove the 4 cross head screws right at the front of the assembly, NOT the six nearest to you when looking at this image. 
  6. Carefully unclip the 4 cable connectors from the motor control board. The other connector cannot be removed from the board and must be removed where it connects to the other board.Tascam BR 20 capstan motor board with cables removed
  7. The whole assembly can now be lifted out from the machine. Be careful to not snag any cables and remember to unclip the black cable ties.
  8. You’ll now be able to unclip the control board from the assembly by carefully compressing the black clips with some needle nose pliers.
    Tascam BR 20 capstan motor board unclipped from assembly
  9. Now remove the six cross head screws holding the capstan motor assembly together. This is the only way to remove and refit the capstan belt. There’s not enough room to do it any other way!
  10. Now you can remove the old belt and capstan shaft. It’s a good idea to clean the capstan with IPA where the old belt has run and reapply a little grease to the bearing end of the capstan.
  11. Fit your new belt and reassembly is the reverse of dissasembly! Be careful though to not drop the screws into regions you can’t get them out of – luckily there aren’t that many on this machine but a long magnetic screwdriver is very useful.. just don’t get it anywhere near the headblock and heads!
    New Teac capstan belt for Tascam BR20 reel to reel tape machine

Tascam BR 20 reel to reel new in box (not for sale)

May 10th, 2010

Tascam Br 20 reel to reel tape machine box

This is something you don’t see everyday! An almost unused and boxed 1/4″ 2 track reel to reel tape machine, a Tascam BR20 one of their highest quality machines sometimes installed with a Timecode head for broadcast and editing applications.

This machine somehow turned up at an IT Recycling centre in Essex but is now in much safer hands transferring tapes, in particular a very large archive of library music on 10.5″ NAB reels owned by Mood Media Ltd.

As you can see this machine is in it’s original box, with packaging and first look at the heads show almost no head wear but some nasty oxide that took a while to clean off.

This machine needed little work to bring it back to spec, a new capstan belt, pinch roller, tape tension and speed setting and a full calibration.
The capstan belt change is the subject of another blog post here..

Tascam BR 20 reel to reel tape recorder

JVC PV-4800E 1/2 inch EIAJ colour portable video recorder

November 21st, 2009


A recent addition to our video arsenal is this rare 1976 vintage 1/2″ colour reel to reel machine.

This has needed some work to get it functioning well such as new belts, hardened grease cleaned off the mechanism, etc but is now able to transfer colour recordings made in this format of reel to reel video.

A more detailed article on the repair of this will appear soon as will information about our other reel to reel video machines, the Hitachi / Shibaden EIAJ machine, the Sony CV-2100 skip field VTR and the enormous Ampex VPR-2B 1″ video machine… and we’ve got two of these!

Thanks to Rich at www.labguysworld.com for the JVC service manuals.

Information Terminals M-300, cassette tape transport alignment gauge

November 21st, 2009

The regular service of analogue machines which will involve the mechanical alignment then electrical alignment / calibration is really important if you’re attempting to get optimum transfers and reduce any risk of damaging the potentially fragile tape.

While some of our machines are serviced by others we like to regularly check them and have gradually bought our regular servicing in house. Of course this needs specialised tools, test tapes and gauges, often totally unavailable new now.

On a lucky eBay day I happened to win one of these beauties, an Information Terminals M-300 gauge. This enables you to accurately set the tape guide height and also the head stroke. It is a universal gauge and can be used across many decks.

information_terminals_m300-boxed copy

Nakamichi tape deck owners have had a hard time doing this part of their servicing as the original Nakamichi gauges are very very rare now as is this.

A member of the naktalk mailing list though recently borrowed our gauge and has had it measured and will soon have a small batch CNC machined and made available. These remanufactured gauges will have a few small modifications to improve the design.

Thanks to Willy at www.willyhermansnervices.com many more tape deck transports will be able to be aligned correctly.

windows user interface button problems

October 27th, 2009

An odd, frustrating but very easy to fix problem appeared on a old Windows 2000 Professional system recently.

The check boxes, task menu arrows and window minimise, maximise and close graphics all changed and made some aspects of the OS more difficult than usual to use. The user thought a virus  or spyware had done this but after realising that these parts of the Windows user interface are characters from a TrueType symbol font, Martlett, the solution is trivial. As in print when a font is missing, software substitutes it with another one that usually always looks odd.

The font was installed but corrupt, using a copy of Martlett from another install fixed the problem immediately. MS has something to say about this here: http://support.microsoft.com/kb/134861

luxury bed and breakfast on Skye – thespoonsonskye.com

October 7th, 2009


A beautiful guesthouse and a beautiful site!

In conjuntion with Bremner Design, we’ve created another simple but powerful WordPress based site that is easy to use and can grow as their business grows. Developed and hosted by us on GNU  / Linux systems.

greatbear analogue and digital media have moved…

September 2nd, 2009

not far though – just upstairs to a much roomier space with better natural light.

Anyone who’s visited will know how much equipment we have and this move has meant quite alot of downtime as we’re taking the opportunity to re-rack, redesign and re-wire. Anyone with existing orders will have these processed as soon as possible but please bear with us for the next week or so….

Our revised address is:

greatbear analogue and digital media
Unit 26
The Coach House
2 Upper York Street
Bristol, BS2 8QN

0117 985 0500

To contact us by email, please use our contact form here…

U-matic transfer to DVD, Uncompressed Quicktime and Digi Beta

June 25th, 2009


We’ve been honored recently to have won a large contract to help in the digital migration of an extensive educational video archive by the transfer from U-matic archive copies to uncompressed video files.

While the archive had been stored in an suitable environment and rarely if at all played, they had not survived well. The Sony branded tapes from the 1970’s and 1980’s all exhibited binder hydrolysis or sticky shed syndrome. We were still able to get good transfers though using our range of umatic machines, particularly the Sony BVU-950P and For-A Time Base Corrector.

DVD video restoration / editing helps convict serial Bristol flytipper

May 19th, 2009

greatbear recently helped the Streetscene section of Bristol City Council in an investigation in a serial flytipper.

DVD footage of the flytipper had been taken by a member of the public of flytipping activity but this DVD had other unrelated footage on that needed removal. The DVD was also damaged and needed slow, repeated reading to rip the MPEG stream successfully.

Using MPEGstreamclip it was then straightforward to trim the stream, resave and create a new DVD with just the necessary footage.

See the BBC news article with the video, http://news.bbc.co.uk/1/hi/england/bristol/8029183.stm

www.rockblastingservices.com goes live

April 3rd, 2009


Rock Blasting Services ,a new site for an African based Blasting, Road cutting and Drilling company. This site is hosted by us and uses the WordPress Content Management System, bringing an appropriate combination of simplicity and flexibility to the project.

Microcassette Transfer to CD helps Crown Court case

April 3rd, 2009



We’ve recently been happy to be involved, with Mobray Woodwards Solicitors,  in the audio transfer of important evidence in a  local Crown Court case.

Even given the poor quality or the recordings, made on the slowest tape speed of 1.2 cm/s we were able to make transfers to CD which were clear and understandable with CD track markings for easy access to specific sections of the audio.

Microcassettes, until recently, were used regularly for voice recording in small, portable dictaphone type of machines. Their fidelity is not high but when used for voice it is usually acceptable.

Greatbear are able to transfer all formats and speed of microcassette in addition to 1/2 speed standard cassettes that were common for voice recording of interviews and meetings in the police service, inquests, etc.

For more information on high quality audio tape transfer and restoration please visit our transfer pages.


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