Playstation laser repair (part 1)
Ok, so you've just installed your Mod Chip, and you've burned your first game, but when you put the game in your PSX, nothing happens, you get to the black PlayStation Screen, but it just hangs. Now you pretty pissed off, and you are cursing my site, and yourself for trying this stuff out. But before you toss that coaster you just made in the trash, you decide to take it over to your friends house, and try it out. As luck would have it, the game works. So why doesn't it work on your PSX? Well there are many factors which lead to this problem. The most common problem is your laser is old. Yup, years of using your PlayStation can actually damage the laser. The older PSXs have lasers that ride on a plastic rail. When the laser moves back and forth over a prolonged period of time, the plastic rail begins to wear, and the laser's lens dips a slight amount. When the lens dips, the light is not reflected back from the CD correctly. There are various fixes to this problem, but the most common is to use good media when burning your PSX games. This means don't use the cheap disks when you burn a game, use good media, with a high reflectivity. Good disks to use are Verbatim DataLife Plus, and TDK Certified Plus. I recommend using the one with the printable white labels, I've had the most luck with those. These CDs are highly reflective, and allow most of the light to bounce back to the lens. The newer PSXs the Dual Shock ones, don't have this problem, Sony decided to put a metal rail on the inside of the laser. But for those of us who've been playing the PSX since it first came out, we need to repair our lasers.
So, how do I go about repairing my laser ?
Well, the first thing to try is to turn the two knobs located on the lower left side of the PSX motherboard. The top knob controls the motor speed of the laser (bias), and the bottom controls the intensity (gain). I recommend that you mark the top of the knob with a pen or marker before you begin, this way you can undo anything that you might have done. You turn the knobs with a small Phillips head screwdriver. It depends on you specific PSX problem to decide what knob to try to tun first, and how much to turn it, but a good rule of thumb is to turn only one knob at a time at fist, this way you can get a good feel for the effect. Also, a small turn might be a huge change, so don't bother to try and spin the knob around too much. Usually if you have slow load times, and FMV (Full Motion Video) skipping, you need to tweak the top knob, the motor speed. Else if you are experiencing freezes in game play, or problems trying to use certain kinds of CDR disks, you need to tweak the bottom knob, the laser intensity.
I've played with the laser knobs, but my video is still crappy, and games load slow. What do I do ?
If you've tried everything, and nothing seems to work, you have three last options, buy an new PSX, and put your mod chip in there, buy an new laser, or try to repair the laser your self. Repairing the laser by hand can is not too hard, but there are places on the web that sell a laser repair kit, that will help you out. If you decide you want to try and fix it yourself, it will be a lot cheaper. Basically what you need to do is to take the laser out of your PSX, unscrew the cover, and remove it. When you get the cover off, you will see a small white gear. You need to turn it over, and squeeze the bottom of the white gear with a pair of needle nose pliers. When you get the gear to pop off, you need to tun it back over, and you will see a long plastic white plate that the gear was attached to. Slide the plate off, it should snap on and off really easily, or with little force. Take that off, and you are free to remove the laser. when you turn the laser over to the bottom, you will notice some silicon grease, and some markings at the back of the laser where the weight is. These scratches and markings are from wear. It usually looks like a very slight dip. What you need to do is to put something in that spot, so that the laser can ride flat on it. The best thing to do is to take a 3.5" floppy drive, and remove the metal cover from it. The part of the floppy that is the thinnest is what you need, so you want to cut it out very carefully, making sure you don't bend it. Then take some super glue, and place it in the worn out spot on the laser. Then holding the thin metal sliver from the floppy disk with a pair of tweezers, place it on the spot you put the glue on. Wait for it to dry, and reassemble your laser. Then try to play your games one you are done. if you are experiencing trouble, try tweaking the knobs on the motherboard.
Sorry that was confusing, I need to get some pictures, and post them here. As soon as I do, I'll post them.
How to fix it :
The most common fault with the PSX is skipping or not reading disks, this problem gets worse as the machine gets warm. This occurs when the laser optics can't track or read the data on the disk. The problem is more apparent with golds (copied ) disks as these can never reflect the laser back as efficiently as an original disk, this is because CD writers cannot burn the pits that form the data on a CD-R disk as cleanly as you get with a pressed disk. Most people would probably not notice this problem until they have fitted a chip and tried using golds, this is not a problem with the chip but the same problem I have just described originals should work the same with or without a chip fitted.
The problem is more apparent in earlier versions of the Playstation, Sony took steps to combat this problem in later revisions of the machine. The very first edition of the PSX (SCPH 1000, 1001, 1002) that allowed you use swap tricks to play copies is the worst for this problem. This used plastic parts in the laser (described later ) which become worn after which the machine would struggle reading disks. The later versions of these machines (SCPH 1000, 1001, 1002 ) came with a modified laser unit that used die cast alloy parts which were much better wearing. The latest revision of the PSX the SCPH-550x series seems to be laser problem free and no adjustments should be made even after fitting a chip, this model does not have bias and gain adjustments..
If you have an early PSX you can see on the following zoomed picture a PSX laser that has a worn sled unit that needs repair, as you can see one side of the laser is sitting lower than the other, this causes focusing problems which cause the skipping.
PSX Lense Servo Adjustment ....
If your machine tends to play better when you turn it upside or on it's side then it is a sure candidate for laser wear and adjustment.
The first thing you try is to adjust the bias and gain controls, on earlier machines this will only provide a temporary cure as the plastic sled may be in need of repair. Adjustment usually provides good results on the later machines that have the alloy sled.
These controls have the following effect....
BIAS : This control sets the default DC voltage flowing through the servo coils in the laser that move the laser lens up and down, basically it sets the default distance between the surface of the disk and the lens. This adjustment is the one that has most effect when adjusting to cure problems.
GAIN : This control sets the voltage that is added or subtracted from the bias voltage by the servo circuits for a given fluctuation. So when you have a slightly warped disk the lens can bob up and down and follow the surface accurately, if this setting is not correct the laser will not accurately track warped disks.
Adjusting the bias control slightly clockwise will increase the bias voltage and therefore move the laser slightly closer to the disk, this is usually sufficient to cure the problem for most machines. With an earlier machine that has a worn laser this may not cure the problem, the laser will either have to be replaced or repaired / modified.
Setting the laser servo to its correct position ...
If you have messed around and twiddled the bias and gain pots and your machine no longer operates correctly you can try to set the controls up to there normal position by using a digital multimeter. Connect the ground on your meter to the metal shielding and the positive probe to the following test point near the laser connector.
With the PSX switched on (beware of live parts in the power supply) and no disk I.E. door switch up, set the voltage at this point to 1.70 volts, on a good laser this should the correct voltage however if your laser is worn you might need to increase this slightly. Once you have set the bias put a disk onto the spindle press the door switch (you may need an assistant to do this) the voltage should rise to something like 0.15 volts higher than with no disk (E.G. 1.85) if its to high or too low adjust the gain control till it is somewhere between those values. Your PSX should now behave it self again.
Modifying the laser.
Modifying the laser is quite tricky so I suggest only real electronics engineers attempt this. Basically the modification has to lift the side of the laser that has dropped because of sled wear. The best way to achieve this is to disassemble the laser and add a small piece of thin sheet metal between the sled parts... see the diagrams later. Only one principle is behind to making your PSX CD-ROM Drive work again, the sled that carries the optics (lens) should be strictly level or parallel with the CD, and all you need to do is devise something to make it level again.
Firstly disassemble your PSX And remove the laser as per the instructions for installing the chip. Once you have removed the laser turn the worm gear on the underside to move the lens into the mid position, otherwise the lens will get in the way of the cover if it is left in its rest position when disassembling the laser.
