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When Things Go Wrong

Article from Sound On Sound, November 1991

Day-to-day use takes its toll on recording equipment, so proper maintenance and servicing is essential to get the best from your studio toys. David Mellor takes a look behind the scenes of Fostex's service department.

Inside an E16.
The engineer is painting to an indicator that shows how many hours the capstan has been running since the machine was new.

Firstly, a big 'thank you' to Fostex UK for admitting that their equipment occasionally — very occasionally — may develop a fault. This is true of all equipment of course but it's not something one is normally encouraged to think about at the point of $ale. But to a professional user, and there are many people out there making a living with Fostex equipment, it is not only important that equipment should be reliable; repairs should also be very quick and easy should the unthinkable happen. After all, if you lose a day's work in a pro studio, you lose a day's pay. The reason I have picked the service department of Fostex UK for examination is that I am the proud owner of a Fostex E16 multitrack (and intend to remain so for several years to come) and even though I treat it with a degree of tender love and affection that makes my girlfriend envious, after around 18 months of use it developed a slight but annoying wow. Doubtless had I chosen Tascam equipment (the MSR16 wasn't around when I bought the Fostex, so I didn't have any real choice in the matter) then it would have given as good a performance, and their service department would have been equally willing to feature in these pages.

For most of us, the experience of having faulty equipment, most often domestic equipment, is unpleasant, annoying, expensive and time consuming. There are plenty of horror stories about the subject, such as the one about the man who took his television to a local repair shop with a minor fault and was told that his set was irreparable. Not content without a second opinion, he took it to the town's registered dealer for that particular make. It turned out that the local Mr. Fixit had removed a perfectly good circuit board from the set and replaced it with one of a completely different type, which of course didn't work. He had obviously been unable to mend the set and had decided to make the most of the opportunity by pinching good components to add to his stock of spares. The situation was fortunately resolved by a couple of phone calls to people in high places, and a satisfactory settlement was made.

The story is by no means typical, but anyone who ever had their car fixed at a garage will always wonder whether the hefty bill is fully justified by the actual work done. Sometimes you may pay someone for their knowledge rather than the time they took on a task. I bought a secondhand car a few months ago, but it wasn't until I installed my stereo that I found the radio reception was really dreadful. The aerial on the roof was obviously faulty, but I didn't have the time or the inclination to start ripping out all the internal trim to check the cable, or to fit a new aerial if that was the problem. I took the vehicle to a car radio specialist and explained what was wrong. When I picked up the car later that day I found the reception much improved, and asked what the problem had been. I was told that the aerial on the roof was for the car phone that had been fitted by the previous owner (my car is the only place I get any peace and quiet, so I can do without such distractions!). The radio aerial was actually the element of the heated rear windscreen, and the aerial amplifier had become disconnected somehow. I had paid £30 for this chap to connect a plug and socket together! But since I hadn't known what the problem was myself, I wouldn't have been able to fix it in a month of Sundays, so I consider it money well spent.


Coming back to the story of the Fostex E16, I had noticed during a mammoth mixing session for CD last year that time and again the piano tracks were not quite up to scratch. There wasn't really any noticeable fault, but they just didn't sound 'clean' enough and I had to go back to the original samples and play them live into the mix using my sequencer. Pianos have always been a problem for tape recorders, which have so many moving parts that the pitch of any instrument can never be entirely stable. This problem is particularly apparent on piano because the sound is very sharp and clear and entirely free of vibrato effects. Gradually, the problem on my E16 got worse and became audible as a distinct wow at a frequency of around 10Hz. I carefully cleaned all the parts that I thought might need cleaning — to no avail. I needed professional help.

At this stage I had three options: I could go to an independent maintenance person, contact my local dealer, or go to Fostex UK direct. I chose the third option because I thought it would be best to go straight to the top, and I have to admit that I thought it would be a useful exercise to see how their service department might shape up. My first contact at Fostex UK was with their Chief Service Engineer, Winston Douglas. I explained that I wanted to bring my E16 to Fostex's headquarters and ask a few questions about how to care for equipment of this type, and also see for myself how a service department operates.


Winston Douglas explains the set up of Fostex UK's service department and its day to day operations: "The service department basically consists of two engineers plus myself, and I'm also an engineer. Our duties include quality control, checking of new equipment coming into the UK, servicing and supplying spare parts to our dealers and customers.

"Day to day servicing first of all consists of customers such as our dealers ringing us up and saying that they have a machine which is faulty and asking if can they send it back to us. We then issue them with an authorisation number and ask a few questions, such as what's wrong with the machine, and the serial number. We also give them instructions on how to send it because one of the most important things is that the machine gets back here to us in good order. Most people tend to throw their cartons away when they buy the machine, but we insist that they should try to keep them. They should break the boxes down flat, save the polystyrene and put it in the loft or shed somewhere because you never know if you will need it.

"All the information about the repair is entered into the computer. This includes the fault description, what we did to the machine, the parts we used and how long it took to do the repair. This information is very useful to us for future reference."

Adjusting the print coil of my E16.

So, if you are unlucky enough for your Fostex equipment to develop a fault, what should you do about it?

"Come to us directly," advises Winston, "I don't believe in having a dealer servicing network; it may be cheaper for the customer because he doesn't have to send the machine to London but one of the problems dealer servicing causes is that there isn't enough feedback. Until you get experienced on a new machine and the faults it is likely to have, you can't really be as efficient as you need to be. One of the reasons why we have a big service department here is so that we can offer a level of service and back up such that our customers don't need to go anywhere else."

Obviously the idea of concentrating a lot of experience into one major service centre, rather than spreading that experience far and wide across the country makes a lot of sense. Over a period of time, Fostex UK's service department will learn what the likely faults are in any particular machine, and also how best to set about fixing them. There is also the benefit of having a close link with the manufacturing arm of Fostex who can use the knowledge gained to improve their future products.

So, if you take Winston's advice and decide to send your machine back to Fostex UK, how should you pack it. I'll bet you threw the box away, just like I always do, I'm ashamed to have to say. (The cost per square foot of a flat in London is too high to devote to packing material that may only be used once in a blue moon). Winston's advice on packing without the original box is to do as good a job as you can at packing the machine in a big enough box, then put that box in a larger box with additional packing material. That way, any bumps and knocks should be completely absorbed.


I was recently working for a friend of mine in a budget studio where the multitrack was in an unbelievably bad state (come on Tony, book somewhere decent next time!) and obviously in need of care and attention, although it still managed to record almost well enough, even though it handled the tape very roughly. So why didn't they get it fixed so that it wouldn't continue to earn the studio black marks? The answer is that most people, myself included, have a certain amount of inertia when it comes to having repairs done. We always expect it to take a long time and be inordinately expensive. But it truth, the cost caused by putting up with faults is even greater in the long run, in terms of poor recordings and perhaps dissatisfied customers. But, as Winston explains, a quick repair job is not always a good repair job. The turnaround of Fostex UK's service department is as fast as it can be, consistent with producing a reliable result.

"Usually we try to work within about four to five days. I think that's quite reasonable. With regard to E16s and G16s that people are using professionally, people tend to want to bring the machine into us and ask us if we can do something while they wait. We can do that, but I don't like doing it because if you bring the machine in and ask us to fix the fault on the spot we will only repair what you ask us to repair. But from our experience we can often see other things that need doing: the bearings might be noisy and perhaps we should change them; the belt might be slipping which means it's worn and it should be changed; the head might be worn and could do with a relap. So we tend to say to customers, 'Please leave the machine with us so we can repair the fault you asked for and then soak test it for at least a day, and then at the end of that day we'll know it works fine'. For a customer to bring it in and take it out straight away, we can do that but in the process of rushing that repair we might miss something.

"We normally give estimates over the phone. First we check everything and form an opinion on what ideally needs doing to a machine additional to the original fault. I sit down and calculate the cost of the parts and labour and then I phone the customer and give him two estimates. The first is for the fault that we have been asked to repair, I say that we can repair the fault and that the machine will work OK but we have noticed that some other things need some attention. It is to the customer's benefit that he has a machine in perfect working order, but we also give two estimates as a protection for ourselves, so we can say that we pointed out something that needed doing but the customer declined."

Winston Douglas, head of the Fostex service department.

An estimate, of course, is provided so that the customer has a chance to find out whether he can afford the repair or not. If the customer decides not to have the repair carried out then there is a standard charge of £20 plus carriage plus VAT, which seems quite reasonable in the circumstances.


From the user's point of view, there isn't much more to looking after your equipment than to keep it clean and to regularly check its correct functioning, which is probably something you learnt at an early age anyway. But when it comes to hi-tech audio gear, it's as well to have the advice of an expert, someone who knows what can happen if you don't follow the correct procedures.

"Some of the things we have seen in the machines that come into our department are unbelievable. These are sophisticated machines and many we see have been very badly treated. All tape machines should be cleaned before and after each session or each use, there is absolutely no harm in cleaning the machines. People have hi-fis and they don't bother to clean them, but many of these machines are being used to make money, and it can be expensive when they go wrong due to lack of care. Even things like the Fostex multi-trackers (cassette based multitrack machines) need looking after. They are comparatively cheap to buy, but when you come to change the head you are looking at a head cost of £60 plus, and the labour might be two hours at £20 an hour. So we are talking about £100 to change the head. If you are going to use the machine for fun then you have got to understand that you have got to keep it clean. Pinch rollers must be regularly cleaned with a rubber cleaner, once a week or so. Heads should be cleaned before each session and demagnetised once a week or every two weeks."

"Some of the things we have seen in the machines that come into our department are unbelievable. These are sophisticated machines and many we see have been very badly treated."

Demagnetisation is apparently not such a necessity as it used to be because steps are now taken at the design stage to make sure that current can't accidentally be sent into the head, when you switch off for example. But if you leave a tape on the machine, then the magnetism on the tape will transfer itself overnight to the head, and demagnetisation will be necessary. Once again, it does no harm to demagnetise, but be sure never to switch off the demagnetiser close to the machine or it will generate an impulse which may magnetise a head or guide so strongly that you'll need a more powerful demagnetiser to take care of it.

"What happens if you don't clean the head is that the oxide stays on the head and builds up. It won't stay on uniformly, it will probably accumulate into a lump and this will prevent the head from wearing evenly as it should. When you do get round to cleaning the head then the wear pattern will be uneven and you will probably never get a good response from the head on all the tracks after that. Tape guides must also be cleaned because if you get oxide build up on the guides they become so caked that they also wear unevenly. Another thing to bear in mind is that lumps of metal oxide can damage the tape by scratching it and gouging out particles of tape. You won't damage the machine if the pinch roller isn't cleaned, unless of course you have a lump embedded in it which will cause indentations in the tape, but it should really be clean. You can see that it gets shiny very quickly if it's not cleaned and this increases the risk of slippage. The heads should be cleaned with head cleaner — isopropyl alcohol — and the pinch roller with rubber cleaner. Don't use head cleaner on the pinch roller or vice versa. They normally come as a kit anyway."


It probably comes as a relief to know that all you need do is to keep your gear spotless, and that in modern equipment there is nothing for the user to service or lubricate. But as time passes, wear is bound to occur even in the best kept machine. This raises the question of what sort of life span can we expect from modern hi-tech gear? The most sensitive components are the ones where rubbing of metal against metal or metal against tape takes place:

The test set up. Clockwise from top left; distortion meter, signal generator, wow and flutter meter, oscilloscope.

"If we take the E16 as an example, the first casualty I would say is usually the head, the bearings second. The guides are not so important, they need to be worn down quite a lot before they become a problem, but when they are worn they can have sharp edges that scrape oxide off the tape. What we can do is either replace the guides or just turn them around, and that saves buying more guides. We always do that when the heads are replaced, because if the heads are worn then the guides are worn too. The brakes are very good on these machines because they have dynamic braking. The brakes will only come on once the machine has stopped. But they do get dirty, and you'll notice the stiffness this causes when you lace the tape up.

"The E16 has an hours meter which records the time the machine has spent recording or playing back. The full scale is 2,000 hours, but this bears no relationship to the ultimate lifespan of an E16. The machine itself will go on and on. B16s (the predecessor of the E16) are still going strong. I saw a B16 come in here just the other day which was so immaculate it was unbelievable. You can still get spares for the B16, although there are some spare parts now for these older machines which are gradually becoming depleted. Manuals, for instance, for some of the early machines are no longer available, but we have copies here.

Heads are always available; the B16, E16 and G16 heads are quite similar, it's just the mounting plate that's different. In the G-series it's mounted from the deck plate but in the B and E-series it's mounted from the top. But no doubt we'll find a way of getting these heads to fit on older machines when the time comes."


Winston's advice on use maintenance is simple: "Keep it clean!" This applies to all equipment, including tape recorders, mixing consoles and anything else you have in your studio. The days are gone when you could fix audio equipment at the local blacksmith...

"The test tapes and tentelometers (instruments for measuring tape tension) you need are too expensive for the average multitrack owner. I think the best thing to do when you first have a new machine, or a new head or overhaul, is to record a few frequencies on the tape at the same level, and copy a good quality recording from CD. Keep that tape so that in the future you can play it and check that the recorder is still working properly.

"If you have a new head fitted, every service company will try their best to put the head on absolutely straight, but it's only after two or three months that you notice the wear pattern on the head. So have a good look and make sure that the wear pattern is parallel all the way down. If it's wider at one end than the other then eventually you will effectively lose some of the tracks and you'll need an early relap or replacement.

"Don't smoke near the machine. I'm not saying this because I'm not a smoker, but we see machines coming in where all the aluminium parts are yellow from smoke. Smoke also causes particular problems with pots and faders. Another thing with mixers is that people tend to keep a lot of the controls in one place all the time. It's a good idea, at least once a week, to rotate all the pots from left to right and to push all the switches. This will wipe off any new dirt that has accumulated and prevent it sticking to the track permanently. That's preventative maintenance I think."

So the moral of the story is simply to keep your gear as clean as possible, and that preventing the build up of dirt is a lot cheaper than having to pay to good money cure its long term effects.


The problem with my E16 was a noticeable wow which wasn't cured by carefully cleaning the machine. I took it to the service department of Fostex UK where the problem was investigated by Masaki Shimmachi. He measured a wow and flutter of 0.075%, which is a low figure but still out of specification, so at least I knew that I wasn't imagining the problem.

The first step was a general check of the machine's condition which started with a look at the hours meter. This had a reading of about 400 hours, so normal wear and tear was unlikely to be the cause of the problem. Nevertheless, Masaki went through the service procedure slowly and methodically, beginning with a check on the tape tension. A reel of blank tape was loaded and Masaki watched the tach roller carefully while alternating between fast forward and rewind. The test is to see that the tape rides at the same position on the roller in both modes. In the case of my machine a slight adjustment to the tension was necessary.

The next step was to check the tension arms visually. They can sometimes be bent by clumsy tape threading, but this was not the case. Next, with a full reel of tape positioned at the halfway point, the machine was put into edit mode. If the tension for this mode is correct, the tape shouldn't move. It didn't, so that was OK. Masaki knew from these checks that there was no transport control problem, so the cause of the wow must be something more fundamental.

At this point Winston Douglas, the head of the Fostex UK service department stepped out of his office for a conference with Masaki. Winston had come across a fault like this before and confirmed Masaki's suspicions on the source of the problem. The capstan motor of the E16 uses a magnetic toothed wheel which induces an alternating current into a coil made from the etched track of a printed circuit, known as the print coil. The frequency of this current is obviously proportional to the speed of the motor, so the control circuitry continuously monitors this frequency to check that the motor is running at the proper speed. What had happened to my machine is that somehow the print coil had moved from its correct position and was no longer absolutely concentric with the toothed wheel, so the frequency generated went alternately up and down, which the control circuitry interpreted as a variation in motor speed which needed correction.

All that Masaki had to do was to gently manoeuvre the print coil into position while measuring the wow. After a degree of fiddling about he got the figure down to 0.04% which is within the specification for the E16 and virtually inaudible. All of this, and a check on the alignment, took an hour and cost me £30 plus VAT, which included the cost of a new pinch roller. A small price to pay to bring my machine back to as-new condition.

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Publisher: Sound On Sound - SOS Publications Ltd.
The contents of this magazine are re-published here with the kind permission of SOS Publications Ltd.

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Sound On Sound - Nov 1991

Feature by David Mellor

Previous article in this issue:

> Sony DPS-D7 Digital Delay

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