MCA DiscoVision
Defect Guide

While the majority of modern LaserDiscs are perfect upon purchase, DiscoVision discs were not so fortunate. From the very beginning, DiscoVision defect rates were incredibly high, and they never really went down. Through most of DiscoVision's life cycle, the average defect rate ran anywhere from 70 to 90%. Some titles ran even higher. Defect rates also varied from day to day, depending on who was running the pressing machine and if the back door to the plant was open and it was raining outside. The reasons for the defects vary, but most can be traced back to the simple fact that producing an optical videodisc is an order of magnitude harder than making an LP record. Clean rooms, with more stringent specifications than even the pharmaceutical and integrated circuit industries, are required. DiscoVision had not identified this requirement at the time, and never anticipated the troubles they had. As a result, everything that could go wrong, did go wrong.

Prior to the December 1978 launch, MCA conducted a study to determine what the costs of finished, packaged discs would be, so realistic selling prices could be assigned to the product. The final selling prices were determined as to allow MCA a tidy profit, and it was figured that as replication grew and costs dropped, retail prices would drop too. Final production costs were defined as $1.50 per completed side, including packaging and shipping. Thus, a single sided title would cost $1.50 complete, Dead Sides were written off as scrap and not included in the final cost. Since the established retail price of a single disc was $5.95, a nice profit could be made by both retailers and MCA. Things did not turn out this way. MCA's costs quickly skyrocketed, forcing retail prices to rise proportionally just 2 months after the launch. In the end, taking into account initial defects, consumer returns and low initial yield, costs to produce a single title ran upwards of $300.00 per copy.

So, what should you expect from a DiscoVision title you just purchased? Well, don't expect the quality of "Twister". (In hindsight, Twister is probably a bad example since it had such awful speckle problems). For a typical 3-disc, 5 sided CAV film, expect 3 good sides and 2 defective sides. That is about average for the life of DiscoVision. If it's a 2 disc, 3 sided CLV title, expect 1 side to be defective. If a seller has more than one copy of a title you want to ask about combining sets to make a viable copy. This is how most collectors have acquired the majority of our perfect DiscoVision discs.

For identifying a genuine DiscoVision defect, we have assembled this list of all known DiscoVision defects. Included with each is the cause of the defect and how common it is to run across it. Some are applicable to discs made today, but most are not.


LaserRot:
Cause: Various
After some in depth research, my stand on LaserRot and DiscoVision has changed. LaserRot is a term coined during the early 80s as a way to describe a LaserDisc, that upon purchase, played very well, but then over time would develop video speckles and possibly audio noise. From the beginning, DiscoVision engineers struggled to determine why the quality of the discs were failing. Product would leave the warehouse having been quality checked only to be purchased by a consumer and returned as defective.

The gamut of defects due to laserrot vary. Some discs have developed light speckling at the beginning or the end of a side. Some sides develop a speckling pattern which stays constant through the entire length of a side. Still others deteriorate to the point that there is no visible picture at all and the audio is just a jumble of frequencies that doesn't even qualify as static.

The original statement made here DiscoVision discs do not rot is not true. Part of what has been discovered is that the discs did rot, but they would reach a rot threshold and the deterioration of the discs would stop. Some believe the discs would rot during the discs "curing" period - after which the level of rot would not increase. This is relatively far fetched because many discs would show the tale-tale signs of rot several months after purchasing.

That said, rot on DiscoVision discs is not progressive. Enough time has passed that any rot to develop on the discs would have done so by now. It's safe to say that the condition of your discs at this late date is the way they are going to stay when properly handled.

Of course, rubbing alcohol baths to remove dead side coating invalidates everything.


Speckling:
Cause: Inclusion
This is the most common DiscoVision defect. Almost every disc is guaranteed to have at least some minor speckling here and there. There are a very few rare sides which look as good as discs produced today. Speckling is typically caused by inclusion, which is simply dust and dirt trapped between the recorded surface and the reflective layer. It manifests itself as red and blue speckles in the picture, and can cause ticks and pops in the audio as well. Some discs are so defective that players may refuse to sync to the disc, or there is simply no visible picture or audible sound. There is no corrective measure for inclusion. Unless the flip side is very good, the disc is utterly worthless.


Drop Outs:
Caused: Missing pits
Most DiscoVision discs also have drop outs. Many have a lot. These are single lines that will pop up in the picture and disappear, or they will hang around, get longer or fatter and then shrink away again. It is caused by missing pits on the surface of the disc and can be due either to a bad stamper or a poorly produced disc. There is no corrective measure for dropouts.


Laser Lock:
Caused: Missing pits, track sync, etc.
Laserlock is a defect where the laser sticks on a track and refuses to advance. Sometimes, the player will either skip backward and get stuck in a loop. Depending on the contents, the audio may start buzzing, which is simply just playing the same 1/30 second portion of audio over and over and over. Laser Lock is caused by missing pits, discs that were not pressed right and have tracks that fall out of the lasers ability to track them, or scratches. These scratches can be on the surface or under the surface. However data layer scratches usually do not affect playback, and are not usually visible on the screen. On rare occasions, laser lock is caused by particles trapped between the two disc surfaces, behind the reflective layer. These can be seen as small bumps in the aluminum. Some of the odd materials noticed in discs include human hair and insect parts.


Return to MCA DiscoVision Home Page
Link to Blam Entertainment Group Home Page
Updated: November 17, 1999
Send comments and mail and/or updates to: DiscoVision
Copyright ©1999 Blam Entertainment Group