machine repair

Guest post: Refurbishment of Magnetic Recording Heads – Terry Summers

Below is a guest post written by Terry Summers from Summertone Ltd. We first encountered Terry because of his expertise refurbishing analogue magnetic tape heads.

As one of the few, if not only, specialist UK-based company working in this area, we wanted to know more about Terry’s work. We were keen to understand the secrets of magnetic tape refurbishment, and whether Terry accepted that obsolescence for analogue media was imminent, as many audiovisual archivists claim. Many thanks Terry for taking the time to write the article, we hope you enjoy it.

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a gap inspection being carried out on an Ampex, half inch, two track, stereo replay head.

a gap inspection being carried out on an Ampex, half inch, two track, stereo replay head

Before I opened Summertone Ltd. I was for very many years, the Managing Director and magnetic head designer for the head manufacturing company Branch & Appleby. This was a specialist company serving the audio recording industry with magnetic heads as a supplier to Original Equipment Manufacturers in the analogue tape and film industry and for replacement heads for other types. B & A was particularly strong in the magnetic head supply for recording on perforated film for the synchronisation and editing of film sound, being the supplier of heads to many OEM studio film equipment manufacturers. The range of analogue heads designed and made by B & A was legion, ranging from 32 track 2 inch to 8mm film heads. B & A also supplied heads for other purposes, magnetic card readers and bank note verifiers being examples.

To be able to refurbish a magnetic head, it is essential to understand the working, the manufacturing principals and the materials used in it’s manufacture.

That expertise is with Summertone and is the reason for its success. The various magnetic materials used (mumetals of various grades, vitrovacs, ferrites etc.) each require specialist equipment and methods of surface finish to obtain intimate contact with the recording medium. A fact that is frequently overlooked is that a refurbished magnetic head has a performance that is superior to when it was new! The reason is that the magnetic losses due to the gap depth are less. So refurbishment not only restores the head’s ability to contact the magnetic material correctly, having removed the uneven wear caused by the abrasive recording medium, but also gives the head an improved performance, essential for the reproduction of archive, sometimes damaged material.

Digital Changes

The audio industry has of course changed with the coming of the digital age, some say for the better, but others disagree. We refurbish analogue heads for studios and individuals that are dedicated to the recording and reproduction of sound with the full complement of all the harmonics that are lost with a digital frequency cut off. We cannot hear them, but they colour the overall sound picture that we hear. That is the reason for the continuation of the use and restoration of the abundance of analogue machines by our studio customers (and some private users also).

The magnetic head is the vital link with the medium and is essential that it is kept in tip-top condition.

There are also many archival organisations that require the services of head specialists. The British Film Institute for instance, prides itself with the fact that the preserved sound it achieves is in many cases superior to the original public performances. This is due to their keeping their magnetic/optical sound pickups in excellent order and then, after transfer, using modern digital techniques to manipulate and store the results. Summertone receives heads from all over the world for refurbishment and is proud and pleased to say that the percentage of heads that it receives for refurbishment that are not able to receive suitable treatment, is very small indeed.

The scarcity of machines can be a problem, but as the number of studios using analogue machines diminishes they tend to pass to dedicated companies and individuals who appreciate their importance and who go to great lengths to ensure they are kept in a working condition or used for spares, not thrown in the skip. We appreciate that this cannot go on for ever, but the indications at the present time are that there are many who have the expertise to help in the specialist areas needed to keep archive machines in good working order.

It is a fact that the older analogue machines seem to be so well designed and built that they have very few faults that cannot be rectified easily. For instance, last week we switched on a 1960s valve recorder that had not been run for very many years. It performed perfectly. Another just needed a simple capacitor replacement for it to also perform. The point we are making is that the older technology was, and still is, reliable and understandable, unlike many modern machines.

It is possible to build new tape head blocks from scratch, but that is really not economical due to cost. We can, and do, still have replacement heads made to my designs but only if it is justified to keep a valuable, scarce, rare format, machines functioning. There are heads around, both new and second hand that can be refurbished. These can be obtained by combining two machines both for mechanical parts and heads. Summertone also has a small stock of heads.

Obsolescence

I do not agree with the archivists who say that there is a 10-15 year span left to transfer material. Magnetic tape and film has stood the test of longevity without deterioration which is why it is still being used for digital archiving. More modern archive methods have been failing. With good maintenance, analogue machines have a good life left and spares are still able to be obtained and manufactured as they are understandable to good engineers. I am sorry to say that when Summertone closes, our expertise for magnetic heads will be lost as it has not been possible to transfer a lifetime of analogue experience to another, due partly to the lack of financial incentive.

Posted by debra in audio tape, audio technology, machines, equipment, 2 comments

Transfer Digital Betacam (DigiBeta) to Quicktime or AVI now, one day they will be obsolete

Even relatively recent born-digital formats like Digital Betacam (or DigiBeta, as it’s often referred to) should be viewed as a potentially obsolete format. This Standard Definition (SD) format while very popular for many years is not the preferred delivery format now the industry has embraced High Definition (HD).

When serviced these machines are very reliable and would be worked hard in a production environment. Designed to be serviced with little expense spared these were some of Sony’s most expensive decks and even if second hand values of machines have dropped recently, new spares have not. As with most video formats though as they become less popular the spares availability will become a problem as parts inventory dry up. One day and it may not be that far away a popular format like DigiBeta will become a threatened, obsolete format.

Digibeta_close up right angle

Digital Betacam recorders  were introduced in 1993, superseding the Betacam and Betacam SP, while costing significantly less, and being dramatically smaller than (!), the D-1.

We are particularly pleased with this machine because there are relatively low hours on its original head drum (1000 hours). The average headlife for this format is up to three times that or more, depending on the environment it was used in.

If the machine was used in a heavy production environment, for example, it would be constantly drawing in air to cool the electronics and, potentially, large amounts of dust and debris with it. This is one of the factors affecting head life.

Part of the service kit installed on the DigiBeta is designed to counter such damage because it allows you to replace the filters around the head drum area should they become clogged.

dvw-a510-digital-betacam-loading-gear

The big problem, as with so many of these machines, is acquiring relevant parts to ensure they can be serviced when they break down. Spare parts for DigiBeta machines can be expensive, costing several thousand pounds for a replacement head drum.

This machine has needed some work recently to keep it running smoothly. The loading gear had split which meant it couldn’t load tapes and gave reel motor errors. These were fixed easily by replacing the broken parts. After these repairs were completed the picture was still however displaying errors. This was because the bearing on the pinch roller was worn resulting in too much movement in the tape path. With the problem diagnosed a new pinch roller was installed and our new machine is working beautifully!

So send us your DigiBeta tapes!

Posted by debra in video tape, video technology, machines, equipment, 0 comments

Repairing obsolete media – remembering how to fix things

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

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 Greatbear 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.

OLYMPUS DIGITAL CAMERA

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, Greatbear will continue to collect, maintain and repair old equipment until the very last tape head on earth is worn down.

Posted by debra in audio tape, video tape, 1 comment

video tape obsolescence – spares supplies disappearing

Greatbear protects tape-based analogue and digital media from the wave of obsolescence faced by these formats. The speed of technological change in the 20th and 21st centuries has been, and continues to be, breathtaking. Consider the amount of tapes and machines that have been made since the invention of magnetic recording tape by Valdemar Poulson in 1894. Since then, the drive for efficiency and better quality has fueled the development of numerous formats which become eclipsed as each new product hits the market.

Close up of a V-MAG Head off an AMPEX 1" Machine

Close up of an individual V-MAG Head off an AMPEX 1″ Machine

Obsolescence for video tape is an issue for a number of reasons. Firstly the knowledge of how to repair older video machines is disappearing: as technology changes, people are no longer trained in the maintenance of such technology.

Another crucial issue is the lack of spare parts. For video tape machines, the most sought after parts are often drum heads. Video drum heads are difficult and expensive to make, they can’t be refurbished and there is no commercial market for them, which makes them rare and sought after.

The nature of recording an audio signal is different from recording a video signal. Because of this, video heads and the video tape transport had to be designed in a different way to audio heads. Audio drum heads are in fact easier to make and they can also be ‘relapped‘ (a sophisticated form of sanding down), so it is a fairly straightforward process to refurbish them.

Because of the specific problems facing video tape obsolescence we have to rely on ‘New Old Stock’, although sometimes it is possible to use parts from scrap machines. These are however less reliable because the drums heads are part of a mechanical process and if used extensively, they will inevitably be worn down.

Betacam Head Drum

Betacam Head Drum

One company – Video Magnetics Inc – remake video drum heads and specialise in the repair and alignment of Betacam SP, Digital Betacam, Betacam SX, DVCAM and DVC PRO recorders, cameras, camcorders and dockables. They do not however cover all the machines we use at Greatbear.

Luckily we are well stocked up with lots of spare parts, mainly through careful collecting with an eye to work in the future.

U-matic Head Drum

U-matic Head Drum

Posted by greatbear in video tape, 6 comments

V2000 bad Frako capacitor in Grundig 2×4 Video 2000

Video 2000 Frako X2 capacitor in Grundig 2x4

Yet again bad capacitors have reared their electrolytic fluid! This time in a Grundig Video 2000 video tape player, or V2000.

Pictured above is a X2 mains film cap in the power supply of the video machine, made by Frako. This brand of capacitors are German and used in many Studer audio tape machines too which commonly have similar smoking fun such as the B67 and sometimes the A80.

A nice satisfying repair though – all Frako film and electrolytic capacitors were desoldered and replaced with 105 degrees rated Panasonics. The circuit boards on these type of machines are also well made with thick tracks so there’s little risk of lifting solder pads with this type of repair.

Other than their ageing capacitors and some dry solder joint problems these Grundig machines are excellent although as with many older domestic formats the important proprietory spares like the V2000 upper head drums are very rare new now so keeping these machines running will get harder and more expensive over time.

It’s a good idea to digitise and transfer any video recordings on formats like Video 2000 to file based digital formats or at the very least DVD sooner rather than later.

Posted by greatbear in video tape, video technology, machines, equipment, 0 comments

Repair Teac A3440 4 track Multitrack Reel to Reel

The Teac A3440 is a classic reel to reel tape recorder from the late 1970s, early ’80s significant in that you could use it to make 4 track multitrack recordings at 15 inches per second, the professional tape recording speed. At the time there was precious little else around at the price to do this so this machine was perfect for small bands and studios who didn’t have the wallet busting amounts needed to buy a larger format 16 or 24 track recorder.

While the A3440 isn’t the last word in high quality analogue recording it has had some significant users in the past none less than Lee Perry who’d used the earlier but similar A3340 on his Heart of the Congos album.

the problems

This machine didn’t initially look heavily used, the heads had little wear but it hadn’t been used in a long while and there was a heavy build up of tape residue on the whole tape path. The capstan was very dirty and in these cases xylene is a more effective cleaner than IPA but don’t get it anywhere near plastic!

This A3340 powered up but the right hand tension arm was hanging at an odd angle and it wouldn’t play or wind.

Time to take it apart – the fake wood sides and rear panels get removed and it’s pretty easy to see what one of the problems is.

teac-a3440 sticky broken capstan belt

A very nasty ‘melted’ rubber capstan belt that took a fair while to scrape and clean off with IPA.

A new belt has purchased online – Teac parts in the UK are a big pain to get hold of through the official channels and I’ve given up contacting them unless I’m desperate for a part I can’t find anywhere else.

The other lack of drive was caused by broken micro switches. When the right hand tension arm is moved up, two micro switches behind the front panel switch power on for the capstan and reel motors. As this arm can get a los of use / abuse it’s common for the micro switches to crack. Both on this example were broken as was the small plastic piece that stops the arm moving too far down.

the repairs

To replace the capstan belt:-

  1. Remove both screws holding the capstan flywheel against the front panel.
  2. Make sure the flywheel is cleaned of all old belt debris.
  3. Make sure the motor wheel is cleaned of all old belt debris.
  4. Refit new belt over small motor wheel, then flywheel.
  5. Replace bracket remove in part 1, making sure you’ve cleaned off the old grease and regreased where the end of the capstan shaft can run.

Although not essential I took the opportunity to remove the whole capstan shaft, clean, check for wear and reoil before putting back. If you do this you will need to reset the endfloat though.

microswitches

teac a-3440 capstan motor micro switch

It’s not possible or worthwhile trying to repair the microswitches as the modern equivalent that fits perfectly is very cheap. Two were purchased from Farnell and replacement is just a case of:

  1. Unscrew and move away the control PCB to get more space
  2. Make a note of or photograph wiring connections for switches.
  3. Unscrew and carefully desolder the existing microswitches.
  4. Connect wires and solder the new switches in.

The arm end stop was repaired easily with strong super glue and after many hours is still holding.

is it working?

In a word, kind of! The belt and microswitches got the deck and transport moving. It will pull tape and make a noise which is great but an annoying intermittent problem started to appear after some initial testing.

When play or wind are selected, large solenoids clunk and release the reel brakes and move the pinch wheel. This was working BUT occassionally and only in play the right reel brake solenoid didn’t move, leaving the brake on, causing the tape speed to slow, back tension to increase and wow to go crazy!

See our next post for the repair of this problem…

Posted by greatbear in audio tape, audio technology, machines, equipment, 6 comments

8 track cassette capstan motor tascam 238 syncaset

We specialise in tape transfers, many of which are multitrack cassette tapes.

Tascam, Fostex and Yamaha sold cassette multitrack recorders in the golden days of home recording in the 1980s and ’90s. The 4 track format was especially popular but an 8 track format was also developed that squeezed even more out of the small tape width of the cassette.

We love these cassette formats and their accessibility helped start many musicians’ careers. Unfortunately one of the best 8 track machines, the Tascam 238 Syncaset also suffers from a common and frustrating problem that renders most of these machines useless over time, the dreaded direct drive capstan motor failure…

The 238 and other 8 track and high quality stereo tape decks, the 688 and 122 MkII and III, used a direct drive capstan motor for precise speed control and reduced speed variation or wow and flutter (w/f). The circuit that controls this motor fails in certain ways causing lack of speed control and in our case the capstan motor wizzing away at a crazy speed, not the 9.5 cm/sec that it should do.

This here is the culprit  – you can see the attempted repairs which didn’t ultimately work.

One common failure is that the surface mount electrolytic capacitors fail or their capacitance changes to such an extent to cause speed problems. These can be changed for standard through hole caps but you do need to be very careful as the tracks are damaged very easily – good tools are essential.

The other point of failure in the circuit is the BA6304F SO16 IC – we even changed this but the motor still didn’t turn!

There was some suggestion from previous repairers that the grease at the end of the capstan flywheel hardens over time. increasing the friction and causing problems with the circuit.

This can become frustrating quickly, especially when you have a large archive of cassettes to digitise.

When we can’t repair we reluctantly do the next best thing and buy the whole replacement part but this is another exercise in frustration. Teac parts and Teac UK don’t have any european supply of this capstan motor (part no. 53700075-01) anymore as of November 2011. Interestingly about 6 months ago they did at around £60 GBP, then about 3 months ago they had one left at £160 GBP!

Lots of emails later to Teac US, Teac Canada and Teac Japan there seem to be a nice stock still on shelves somewhere and at reasonable prices UNTIL you ask them to ship to the UK when you discover they can’t do this and I’d need to go through Teac UK!!! I’m pretty persistent but I gave up finally even though some of the support staff tried to be pretty helpful.

We find support for older machines from the original manufacturers is not good generally and unreasonably expensive when you can find it. This is similar across audio and video, semi-pro and professional products. Some companies are easier to deal with and have better parts situation than other but stockpiling machines, parts, manuals and obsolete knowledge is the best course of action.

What we finally did that worked and was a good solution was purchase 3 Tascam 122 Mk III stereo cassette decks which use the same but a later revision of the capstan motor, (part no. 53700121-00).One machine was donated for the cause and the capstan motor removed, modified and refitted in the 238. The 122 motor has a few factory extras, such as these resistors, shown here:

You also need to solder / desolder the speed pads, to change the motor speed from 4.8 cm/s to 9.6 cm/s that the 238 needs to run at.

It’s also a good idea once you’ve got the capstan motor apart to clean the old grease from the seat, check the end float which can be adjusted using the screw shown on the left and apply new grease to the capstan end.

Put it all back together – be careful to solder the wires to the motor to the correct pads – they’re different on the 122 and test… Ours worked almost perfectly.

As the transport hadn’t been used for a while the reel motor would intermittently stop as if sensing the tape end. This can sometimes be loose counter belts but on the 238 it’s a digitial counter. We cleaned up the leaf switches on the transport top and also sprayed a small amount of deoxit into the inside of the reel motor. A bit more use and it finally worked to spec…

For 4 track and 8 track multitrack cassette transfer, see our dedicated page, and please contact us for more information.

 

 

Posted by greatbear in audio tape, audio technology, machines, equipment, 8 comments

Sony PCM 7030 DAT repair

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 machine 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 way 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.

Posted by greatbear in audio tape, audio technology, machines, equipment, 4 comments

Replace pinch roller on Sonifex NAB Cartridge machine

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.

Posted by greatbear in audio tape, audio technology, machines, equipment, 8 comments

Video time base corrector self destructing mains socket

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 1990s 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), U-matic DUB High Band/Low Band and component inputs and outputs.

Out unit still has its 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 leaking 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.

Posted by greatbear in video tape, video technology, machines, equipment, 1 comment

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

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 its 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.

Posted by greatbear in video tape, video technology, machines, equipment, 1 comment

Replace Tascam BR 20 Capstan Belt

We have two of these excellent machines in addition to our Sony APR 5003s and Studer A80s. 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
Posted by greatbear in audio tape, audio technology, machines, equipment, 2 comments

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

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 its 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

Posted by greatbear in audio tape, audio technology, machines, equipment, 12 comments

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

jvc_pv_4800e_reel_to_reel_colour_video_recorder

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.

Posted by greatbear in video tape, video technology, machines, equipment, 0 comments

Information Terminals M-300, cassette tape transport alignment gauge

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 brought 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.

Posted by greatbear in audio tape, 7 comments