1982 Philips LaserVision VLP-600  

I have one of these. I bought it in 1984 new from Laskys in London they were selling them off cheap (£50). I must have bought around 30 discs. The one which is interesting is The David Attenborough Garden of British Birds  due to it having CEEFAX. Mine gave up in the early 90.s it seemed to me that the problem was the laser. ( Noisy grainy picture) Not having a circuit diagram did not help. I will be watching with interest on how you go on.

Unlike a DVD the Laser disc records the whole video and does not use video compression. It has two modes of operation. In linear mode the disc rotates at constant speed (plays for 35 mins). In the other mode it is constant linear speed so the disc slows down as the laser beam which starts at the label and moves out to the edge of the disc.(Opposite to a record). This plays for around 60 mins and of course the discs are dual sided making 120 mins.

I personally knew the guy who gave training courses on these at Philips. We were mates as well since he lived not far away. He demonstrated that laser by having one hooked up to the demo machine since anything 'laser' seemed incredibly futuristic. To demonstrate the beam he shone it towards the far wall and then blew chalk dust in front of it that clearly showed the invisible beam. Was probably around 1981 or 82. 

Haven't been in contact with him for years since life changes for everyone and he moved away. I wonder if he still has any of his notes.....it shouldn't be difficult to trace him since my wife is still in contact with his ex-wife.

I seem to recall that the focus lens, or rather the coil that activates it was problematic on early machines. 

I can't remember if the discs were double-sided or not......

I've come across Laserdisc in various forms over the years, I worked for an education authority and we were trained on the BBC Doomsday book project with a BBC computer and an industrial Philips laserdisc player, an excellent system but a bit too fragile for the rigors of use in '80s secondary schools.. 

Then the BountyVision contract, the Philips unit shown above with a Thorn TX10 TV modified for CVBS input all in a wooden cabinet, with large buttons to select various short programs about breast-feeding, baby-care etc. I'd replace the discs every few months in about 20 units, never saw a TV or Laserdisc issue in about 5 years. There was an interface board and some hard wired connections for the chapter selection buttons.

BBC presentation used laserdisc for the symbols in the late 90s again using Philips players, controlled by the Probel Map and Compass automation system.

I've owned a Pioneer CLD-D515 player from new (1996) and have a collection of 1990's classic films on disc which I delve into occasionally. The NTSC discs had space for PCM and analog audio, so these were the first discs to have alternate or directors commentary. The PAL discs could only have one or the other. A good format, never really took off in the UK, but I remember Tower records in London had a huge Laserdisc section. I used to order mine mail order from a company in France who would accept payment in Sterling.

Posted by: sideband

I can't remember if the discs were double-sided or not......

They were indeed and you had to flip mid movie also many titles were across multiple discs, another nail in the formats coffin.  A later, more sophisticated player from another manufacturer had its optical reader on a gimbal type arrangement that flipped itself over rather than the disc but that did not help with a multi-disc title. 

Posted by: crustytv

Posted by: sideband

I can't remember if the discs were double-sided or not......

They were indeed 

Just like the interval at the cinema, time to get the ice creams, for those of us who remember the sales lady carry the ice cream and drinks.

I remember I had 'Raise The Titanic' and 'Towering Inferno' borrowed from the Philips library and a VLP600 also borrowed for the Christmas period. I had the VLP600 connected to the hi fi for audio and we enjoyed both films over Christmas Day and Boxing Day. Everyone was very impressed with the quality.

There was apparently a copy of 2001 on laserdisc but I never found it....not in the Philips library anyway. 

Thus far I've only got three laser discs, these are purely for testing purposes for when I attempt the player repair. No point investing in a library at this stage until I've sorted a working player or indeed if it is at all possible from the pair I've got.

The many sources I've read on the web would seem to indicate a significant number of these players end up being door wedges. The main problem nowadays and apparently occasionally when new, was the mirror glue. The player uses an elaborate chain of mirrors and from what I understand many (not all) suffer with this glue failing with a tendency for the radial and tangential mirrors to jam in their servos. The glue that holds the magnets behind the mirrors weakens with age. If a magnet detaches, the mirror jams solid, but the magnets can also migrate outwards and cause sticky behaviour.

Its not a total show stopper if you've the toolkit and experience. Re-gluing the mirrors requires an optical realignment and refitting them is a highly skilled job requiring a lot of equipment and complex circuitry responsible for tracking and focusing the laser beam. Its not a task for those that don't have the tools and/or experience. Like many others I have neither the experience nor the correct tools so If I hit this mirror type of fault I'm pretty much done for. The tools required for an optical alignment are as follows:-

• Mirror alignment tool
• adjustment eccentric
• pupil timing meter
• control box & connecting leads for PQRS linking Pupil meter and scope inputs
• Dual trace oscilloscope
• LF generator with low output impedance
• adjustable regulated PSU
• Test Disc

I'll start as usual with checking the power supply rails are present +/- 12V rails for the video servos, 1150V rail for the laser, +/- 20V for the turntable. Along with the making sure the reference voltages across diodes 7102/3 are stable and the number of protection circuits are OK too. If these are then I'll replace the sled belt and pray the Radial and Tangential mirrors are OK, If not it will likely be a non starter project.

Below a couple of photos of the three discs, two are double-sided, multi-disc ( Schindler's List & Braveheart) the other is a double-sided single. The second photo is to show the alternative competitor of the time, the C.E.D disc (Forbidden Planet). As a comparison, I think this clearly demonstrates the sheer size of the C.E.D. disc format and that you inserted the entire caddy into the CED player as you could not touch the disc or risk getting any contamination of the surface, unlike laserdisc.

I vaguely remember an optical alignment jig with cross-hairs etc for aligning the mirrors or at least checking them and deciding what needed replacement. 

OK its not good news, the best looking player which was featured in this threads initial photo's has the infamous ticking. I believe this indicates the Tangential and Radial mirror servos are stuck and almost certainly due to the glue failure problem I described above. Upon checking its confirmed and pretty much makes it terminal for this player I'm afraid, it can however if I'm lucky with the second player, provide a source of useful spares.

My attention now turned to the second player and with fingers firmly crossed I proceeded to see how this next one behaved.

This player has two case panels missing, the power switch was loose and not seated or screwed into its position behind the switch paddle. The sledge belt was again a rubber band and alarmingly there was a fair bit of rattling and tinkling as the case was rotated.

Upon opening up the unit the source of this tinkling was found. It turned out to be two metal spring clips and plastic mounts that hold the front control panel PCB to said plastic peg mounts, they had broken away. Thankfully the PCB has four in total so the remaining two seemed to hold it in place. With the power switch refitted and the rubber band replaced with a suitable one for the sledge, it was once again time to power up, please no ticking!

When the player was activated there was no ticking, Woo Hoo!

I've also read if you get past that major hurdle then you're likely going to end up with a working player as the glue if it was going to fail would have done so by now. The platter spun up and the movie started. However after the first 2-3 seconds in, the picture appeared but was soon lost in a sea of unlocked mess, much the same as you get when the line speed of a TV is not locked. The sound was all garbled and with the movie unlocked it looks like everyone is rushing about, I hazard a guess its running way too fast (servo?) also by the looks of it there appears to be a lack of chroma.

So Igor as I've called this player, might be Dr Frankenstein's potential monster? Perhaps I have a fighting chance IF I can figure out what is causing it to run too fast and if I can fathom that, then chase the chroma. Time to read the rather large and complicated service manual (now in the library)...... Gulp!

Delving into Igors (second VLP600) problematic playback, it would appear the +/- 12V rail is in question.  I seem to have incorrect and erratic speed on the main drive, I checked the output on pin 7 of IC7408, an LM311 voltage comparator. There should be a +12V oscilliscope waveform present, there is nothing to speak of!

Opening the door of the player and checking for the -12V output on the collector of TS7112 (BD675 NPN Darlington +diode) also reveals just mili-volts, perhaps the darlington is dead? I'll have to remove it, now the hunt now starts in earnest to chase down where my -12V & +12V rails have gone.

p.s
Makes me have a new found appreciation of the simplicity of the CED format. ? 

Japan was one country where Laserdiscs caught on quite well.

Pioneer were still making machines into the early 2000s, possibly after the last disc was issued.

Hi Chris,

Just briefly going back to the first one with the 'ticking' noise, you may be right about the radial and tangential mirrors but it could be the focus lens bobbing up and down trying to focus but not able to because the laser isn't working. It's typical 'chicken and egg' situation with these that have multiple feedback loops. Just because there have been problems with the mirrors doesn't mean that yours has.

Posted by: sideband

Hi Chris,

Just briefly going back to the first one with the 'ticking' noise, you may be right about the radial and tangential mirrors but it could be the focus lens bobbing up and down trying to focus but not able to because the laser isn't working.  {...} Just because there have been problems with the mirrors doesn't mean that yours has.

Hi Rich,

I didn't state in the post above (apologies) that I have been thorough in my evaluation of the fault condition. The laser is indeed working, I know this because I went as far as removing the cover off the mirror box and with my safety hat on the laser beam is visible, a rather hypnotic deep red. I do think it is game over for that player, though I may have a play at a later date to see if I can free the mirrors up. For now I'm going to concentrate on the player which looks more like a promising candidate, just need to find where my +/-ve 12V rails have run off too.

re-post of the picture above

Someone mentioned grainy picture above. There's a feedback resistor which controls the laser power. Goes HR, which cooks the laser (and I seem to remember the discs too!) 

Damned if I can remember which one, only did a couple back in the 80's.

Posted by: crustytv

Posted by: sideband

I can't remember if the discs were double-sided or not......

They were indeed and you had to flip mid movie also many titles were across multiple discs, another nail in the formats coffin.  A later, more sophisticated player from another manufacturer had its optical reader on a gimbal type arrangement that flipped itself over rather than the disc but that did not help with a multi-disc title. 

The second side was for mechanical strength as per vinyl recordings. It was sometimes left blank or contained a dummy recording. Early prototypes used colour-under with limited video bandwidth and double the playing time. That was dropped in favour of full bandwidth recordings on the grounds that a second side was needed anyway. Some later music titles were issued on single-sided polycarbonate discs but were not 100% compatible with early players.

This is going to be a long haul thread, getting one working player from the two is going to be a challenge as both have their suite of problems electrical and mechanical. Thus far I've established player No.1 has the frozen radial and tangential mirrors.

Player No.2 appears to have a problem with main drive not running correctly (too fast, erratic with resulting sync loss). As mentioned above the 12V output and resultant waveform from the LM311 i.c was not present , however initial back checks on the immediate likely culprits TS7116/TS7112 and IC7408 revealed nothing, all are innocent. I then noticed the laser sledge of player No.2 seemed to have stopped advancing, removing the sledge revealed a broken/missing tooth on the drive cog.

Player No.1 sled drive gear is OK, so as the mirrors are frozen on that sledge I plan to remove its good drive and fit it to Player No.2 that has good mirrors but a broken drive. The intention of having one good working laser sledge. As this requires both players to have their sledge removed, I will then have the choice of testing the working sledge in either player. 

All fun and games, I have a sneaking suspicion there's a whole more can of worms in the shape of faults that are yet to be discovered, hence this being a long haul project.

The good sledge drive was removed from the seized mirror sledge and installed on the sledge with the working mirror but broken drive.

Now the fun comes, installation and realignment of the sledge.

With a now fully refurbished slide drive installed into the laser sledge with good mirrors, I decided to fit the sledge to player No.1. The idea behind this being that it will further confirm my belief the player No.1 radial and tangential mirrors are at fault and not some other related problem with U1017 (radial drive) or U1019 (tangential), though based on the audible evidence of the ticking at rad/tang mirror location makes me 99% certain.

The actual installation of the laser sledge is not too bad, a bit fiddly especially when trying to get the right tension on the upper guide rail. I greased all the contact points on the sides of the sledge and the drive rack. Then came the moment of truth, the power on of player No.1.

If you remember player No.1 originally did nothing other than the constant ticking when started up as the mirrors tried to adjust. This time when the machine was powered on there was no ticking, which confirms the fault I suspected with the original. The machine came up to speed and unlike Player No.2 which had incorrect, varying speed, this was at a settled constant. Unfortunately although the screen shows it is receiving a signal from the player, all I get are a few dots here and there. The chapter button brings up the on screen display but that's about it.

Chapter ident displayed and you can just about make out the dots on screen

So it would appear player No.1 has additional faults that need investigating. Now I could go off on a fault hunt with this player as it appears to be running at the correct stable speed but although there appears to be some sort of output I've no idea what or where to start. I'll have a read of the manual and see if there's something I can fathom what might be going on, however I still think player No.2 with the missing +/- 12V rails is the more promising prospect. At least that player is reading the disc and plays content albeit at an incorrect speed with no sync.

Therefore tomorrow I will spend a little time investigating the blank screen output on player No.1. If that looks like a huge rabbit hole to navigate, I'll remove the sledge from Player No.1 fit it into player No.2 and resume where I left off before the slide drive gear failed. In which case  seeing as TS7112, TS7116 and IC7408 were innocent, I'll restart my investigations on the +/- 12V rail right back at the source, in the PSU and also check interconnects.

Now you have some results from player #1 maybe an idea just run over the +/- 12V rail and make a few notes so that when(if) you transfer the sledge over to #2 you have an idea of what is going on with the 12V rail on that one.

IIRC the discs were made by layering transparent acrylic & pure aluminium sections together.

As the aluminium could corrode slightly in contact with air, it needed either a backing section of acrylic, or else be bonded to another acrylic & aluminium combination to form a double sided disc.

In some atmospheric conditions the glue used to bond the aluminium sections together could come unstuck, or else cause "laser rot" where it reacts with the aluminium to become unreadable by the player.