SONY PSX DESR-7000 DVD Based PS2 Games Won't play

So was talking to a seller on some trading forums who has a PSX DESR-7000 250gb for a very great price. There is a language barrier between us, but he says "Can no read DVD disk but play PS1 and CD PS2 games fine."

Anyway I am taking it that he means that for whatever reason the DVD reading function is a bit off. Now I have fixed many a PS2 laser problem in my time and have seen some weird things where the blue bottom discs (CD) play and the silver bottomed (DVD) ones don't or vice versa, was wondering though how different of a beast the PSX is and if it could be a simple calibration/alignment issue or if l there is some model of PS2 laser that I could replace it with. Any thoughts on the subject would be great!

 

It seems that they all have KHS-400C lasers, like with most of the retail PlayStation 2 consoles made around that time (2003). The other laser is for recording, but I don't remember it's model number.

 

When you have systems which have more than one laser emitter you can have such faults. On the PS3 you have three laser diodes, one for CD, one for DVD and one for BD.

It can get that messy. But SONY on it's infinite wisdom decided to make it in a way if the BD laser goes bad the laser won't read any other kinds of discs... lol

 

In PSX DESR-5000 - 2 laser heads. KHS-400C and KWS-200A. Possible that in the DESR-7000 they cost the same, I do not know.
Repairing my DESR-5000 I saw (looked at the side of laser operation at the dismantled PSX) :
KWS-200A is primarily responsible for the recognition of the disc. If the CD or DVD discs PS and PS2, then control is passed to KHS-400C. The same thing happens if you load the disc CD audio.
If you load a disc DVD-Video or DVD is clean, they will read the KWS-200A. For DVD recording drive is also responsible KWS-200A.

 

Very good to know, My DESR-5000 has a similar issue and changing the KHS-400C did nothing, and that laser even worked in a normal ps2. but now I know its the other laser with the potential problems.