How bad is it? ( DVD pot = 620 Ohm)

[metallicaband]

Hi all,

Recently I've been getting some DREs with some of my Originals/Backups, I tried to clean my lens but that didn't help, so I tried to adjust the laser's voltage, and was surprised with the stock settings:

CD pot: 1250 Ohm

DVD pot: 740 Ohm

At first I thought I mixed up between the CD and DVD pots, but I double checked, and the settings I've just mentioned were indeed correct.

So I adjusted the CD to around 800 Ohms and my CDs were playing fine again, and I had to adjust my DVD's pot to around 620 Ohms to be able to play some of my DVDs again (I was decreasing around 40 Ohms everytime BTW to reach the # of Ohms required to play my games).

So my question is: What's the worst thing that could happen to my Ps2 with my current voltage settings ? is laser replacement the worst case ? because I already was going to buy a new laser, but thought I'd give the laser voltage settings a shot before doing that..

Few more notes:
-My Ps2 is PAL V4
-Laser is KHS-400b
-I've bought it in 2001 (or sometime close to that, can't remember well) and I've modded it the same year (Messiah clone chip), so I guess the So Called professional adjusted the Ohms that low, I guess I'm lucky that my Ps2 lasted this long !


Any help would be really appreciated..

[Jacques]

I remember a setting of 650 ohm on a KHS-400 B laser wich worked for months without problem (let my kids played with it as showmodel).
But now I use a ps2 as a lasercurrentmeter, 52 mA for a new laser, all above 60 mA is close to death or dead already.
Some laserdiodes die with giving a weak light, some still give a strong light but its not coherent anymore its changed in a LED.
The pot setting can allow the current to go up to 160 mA.
First the ps2 try to read with a low current, when this fails the current goes slowly up and this current limit is set by the pots.
So turning the pots to get a bad DVD to read is not a good idea.
Clean the lenses, the lenses inside can be dirty as well, check the cogs.
If that is done try to adjust the pot with very small steps and using a perfect disc.

[metallicaband]

Thanks for replying, the only thing that I didn't do yet is to clean the internal lenses and that's because I didn't have the right Torx screw driver to open the laser unit (I'm going to clean it in a couple of days after buying the screw driver required and see if the games will work then with more Ohms..).

The problem is, my favourite games aren't playing on my ps2 (MGS2, MGS3 for example), and the disks are perfectly fine, and work great on my friend's Ps2.

So, lets say I cleaned my internal lenses and still didn't get a result without decreasing the DVD pot to 620 Ohms, you said this setting worked for your kids Ps2 for months, what happened later ? if the laser just dies, that's not a big problem to me, as I said, I already was going to buy a new laser now, so buying one after a few months would be fine..(but if the whole Ps2 will die on me, it would be beter to get a laser now if decreasing the voltage still didn't work after clearning the internal lenses)

[Jacques]

Maybe first check with a good lightsource and a lens if the inside lens is very dirty or not before unscrewing things that are later hard to get back on the right spot.
Sometimes I lift the coils to clean the lens, if the machine is very dirty inside than you have to clean all surfaces.
I repaired many old playstations wich were inside totaly covered with thick layers of dirt and dust and smoking tar layers.
Those old lasers were much better than the later ones, after cleaning many of them worked fine again.

And that ps2 with the laser on 650 Ohm, well I sold it ! after some months and never saw it back.

[l_oliveira]

Lasercurrentmeter ? Where did you get a such wonderful tool ?

When I repair lasers I use a serial connection to the PS2 DVD controller chip and some software which gives me the jitter reading. It allows me to adjust the skew (black screw on the laser arm) and the tilt (the white gear) but it doesn't tell me the laser current. I can still see the jitter float too much if the laser is weak but the tool were not designed to aid with the laser power adjust.

So a laser current meter would be awesome. Can you give me more info about it ?

[Jacques]

Its very simple, I removed the both the CD and DVD fuses and have a laser current reading on good quality digital current meter.
For some time now I measure all the lasers with this, using the Sony data sheet as reference.
But I am very interested in the serial connection to read out the jitter, I know mr brown's serial interface connected to the processor to see boot messages , is this the same interface?

[l_oliveira]

No, that one is the Emotion Engine serial port.
And what you see there is the EE chip printf output.

The serial connection I refer to connects to the DVD drive microcontroller (mechanics controller)

[_Crack_]

Im very interested in oliveiras method to adjust lasers, can you tell us more about it and how to do it?