DA-88's are Going Down!

Tascam DA-88

The failure of surface mounted electrolytic capacitors looks set to bring the life of the Tascam DA-88 and its descendants to an end.

I have worked on Tascam DA-88 machines for years and must have seen hundreds of them.  These days, these machines are rarely used except for retrieving the occasional backup.  I rarely see these machines any more.

The DA-88 was a well-constructed machine, using expensive double-sided boards with high quality components and discrete capacitors - mostly!  Early DA-88's had a few problems, such as clutch and braking problems and at one stage a crook batch with an incorrectly manufactured cam follower that ultimately caused the mechanism to fail.  TASCAM revised these parts and if these machines were updated, these and later machines proved to be very reliable.  Many people preferred the DA-88 and its derivatives to ADAT machines due to their superior reliability, superior sync performance when slaved to other machines or systems and longer playing time.

I have just looked at a DA-88 for the first time in more than a year.  This machine had multiple problems, .  The mechanism and drum assembly appeared to be in good condition.  I checked the obvious things like the power supplies and for leakage around the backup battery, which I have known to have caused problems with some machines due to track corrosion.  In this machine, all of these things were OK.  On face value, all of the problems seemed to be unrelated electronic problems.  In the past, I have rarely had to work on an electronic fault in a DA-88, except when someone has blown one up by attempting to make their own incorrectly wired sync lead!

I became suspicious as to how there could suddenly be so many unrelated problems with one machine at the same time, trying to find something in common which might cause this to happen.  I decided to tackle just one problem first - the head output - figuring that if the head itself was fucked, the machine would have been a financial write-off anyway.

I started by looking at the RF preamp, which is mounted on the back of the mechanism.  To my surprise, the first stage was delivering an output for both heads, putting the drum assembly in the clear.  I quickly found that the second stage for one of the heads had no power.  I traced the +5V track and found the place where the power abruptly stopped - right under a surface mounting electrolytic decoupling capacitor.  Removing this capacitor revealed that the track had been eaten away by the acidic gooey liquid contents leaking from this capacitor!  A quick cleanup and repair and I had both head outputs and ATF tracking working.

But this was by no means the end of the story.  I had almost 100% error rates (with the ERROR indicator permanently on) and all of the other faults.  In fact, the machine finally got to the stage where it would no longer boot at all.

I took a closer look at the other capacitors on this board (about 10).  Nearly all of them had tel-tale signs of corrosion around them.  But this board appeared to be working - the other problems must have been elsewhere.  I decided to have a quick look at all the other boards in the machine.  The Main System Board, Sync Board, A/D Board and D/A board all have high quality discrete capacitors, with no visible signs of any problems.  However, the vital DSP Board was covered in surface-mounting electrolytic capacitors (around 30) and every single one of them had corrosion at their base!  That would almost certainly account for the booting and tracks 1/2 problems.  There was definitely something wrong with the Record/Play Board, probably causing the high error rates.  It too was covered with surface mounting electrolytics with lots of corrosion.  Finally, there was the mechanism Servo Board, which also had these same crappy capacitors.  Normally, if this sub-system does not boot, you get the error message "Hung Servo" in the display, but in this case, it appeared that this was the one bit of the machine that was working properly.

So all up, I would have been looking at replacing around 60-70 capacitors.  The component cost would not be high, but the labour involved with cleaning up and repairing the damage for each and every one of these would be more than the value of the machine.  On top of that, there would be no guarantee that the heads were OK (naturally, the backup battery was also flat, leaving me with no idea how many hours the thing had chalked up).

In the case of a DA-88, I would consider the job "do-able", since this model has relatively few surface mounting electrolytic capacitors.  But DA-38's, DA-78's and DA-98's have much cheaper boards, featuring many more of these horrible devices and would probably be out of the question to repair.

Surface mounting electrolytic capacitors are bad news.  Manufacturers must realise that they cannot use them if they want their products to last.  (And while they're at it, don't ever mount batteries on PCB's!)  Please do not think I am trying to dish Tascam here.  I was already aware of this problem in other machines, including top-end Sony DAT machines, cameras, Beta machines and so-on.  Nearly all DAT machines, video cameras and many other products including the revered DigiDesign 192 use the same type of capacitors!  It is outrageous that people must pay such a high price for equipment that will not last longer than ten years.

The DA-88 I looked was a relatively early machine.  Hopefully, there are still some of them working out there.  But the writing is on the wall.  I am convinced ALL of these machines will die within a few years after seeing this one.  Be warned!  If you have important material archived in this format - get it off NOW whilst you still can!

Colin Abrahams - 2007

Postscript

In more recent times, the market has been flooded with almost unbelievably inexpensive equipment.  If anything, the life prospect of much of this stuff is even shorter, sometimes only a few years.  On top of this, the serviceability of this equipment is often very poor, making it uneconomic to repair.  That's assuming that the equipment is not intentionally made obsolete and rendered unuseable by the manufacturers.  We have truly entered the throw-away era and in the long run, everything from washing machines to analogue converters will cost us all much more.