PS1 DTL-H1000 Debug PS1 Laser Replacement Still Unable to Read Disks

A Toubib

A Toubib

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Joined
Dec 10, 2020
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11
Hey community,

I've got an interesting one for the crew.

I've had a DTL-H1000 debug that's been sitting on my shelf for a while unable to play games. I've assumed that the laser was bad based on my past experiences with PS1 consoles. However, I replaced the laser but have had no luck getting it to read discs.

So far,
  • I've replaced the laser unit with a KSM-440BAM from a PSone. (I've also tried a second KSM-440BAM from another PSone) Neither of these seemed to fix the issue so I went about adjusting the laser and have set:
  • Pot intensity to 11.4mv
  • Bias to 1.7v
  • Gain to 1.82v

Still no dice. Any thoughts on what my next steps for debugging should be? The PS1 boots up fine and shows the Sony Computer Entertainment white screen, but doesn't proceed from there.
 
I went into a rabbit hole today to try to figure out if it's maybe the replacement laser.

I took out another PlayStation and swapped lasers. KSM-440BAM worked in the other unit, so I know the laser is good. (I also took the laser from the other unit and tried it in the DTL-H1000, no dice)

I then took the reading of the other PlayStation, oddly it's no where close to whats documented online on Bias or Pot intensity, the readings I got were (unadjusted by me):
  • Pot Intensity 12.9mw
  • Bias was 1.52v
  • Gain was 1.80v
This unit works perfectly fine, so I'm not changing anything.


I tried to do those values on the DTL-H1000, no dice.

However, I ran into an old online post that CL708 and CL710 should be as close to 0V as possible (see photo below)
PS1Laser.jpg

So I tried these setting:
  • Pot Intensity 12.3mw (can't adjust anymore, on this laser the adjustment knob is stuck (the other laser I had that could adjust didn't work on the other unit so I abandoned it. This laser worked on the other PS1 unit I tried on with no modification so in theory it should work.)
  • Bias 1.74v (This Bias sets CL708 and CL710 to 0V)
  • Gain 1.80v (this got me the closest I think to a working laser, I tried 1.82v and 1.84v but it didn't want to spin fast enough at those settings)

These settings I feel are getting me closer to the final result. The big issue I'm seeing between when the laser works (on the other unit), and when it doesn't (on the DTL-H1000) is disk speed. On the working unit, the disc really gets to spinning when loading up. On this unit, it only spins up fast sometimes.

On the settings above, I got it to spin up fast a couple of times, in which it gave me this error. I can't read it but I assume this is a "disc read error / please enter a PS1 disk". I also got to a PS1 black screen (the screen of a game proceeding the PS1 white screen) but it froze afterwards.

DSC_1168 (2).JPG

Any ideas on what I should be doing next?
 
It might seem stupid but what region disk's are you trying to use? I think that model will only run NTSJ
 
OK if you're getting that "Not a PlayStation format disc" screen then it's obviously recognizing the disc and reading at least well enough to get the TOC and determine it's an XA data CD, but then failing disc authentication for some reason - since it's a debug, this can't be wobble related (well, unless someone swapped a retail board into it) and has to be down to inability to read the disc.

My guess is that the signal quality is becoming degraded when the console switches to x2 to read the data - start by trying a different PSU (probably not this, but it's easy to check) then check for iffy looking caps in the CD analog sections - they are known to leak, and a frosty looking appearance on the solder connections is a common sign. Another (fairly common) problem is that the BTL driver (IC722) is failing and the drive can't run stably at 2x speed - try comparing the 2x speed with a console that's working.
 
Check if area around outputs on the back side is gray or black. If it's gray then board was probably swapped.
 
I think you started with this guide http://dogbreath.de/PS1/LaserAlignment/Laser.html depending on the values you posted.
They work fine for retail, but for playing retail on debug you need trail and error the voltages.. It can take a very long time to find the correct values where your drive read all the discs. Personal i adjust the drives for the purpose.
 
Look on the bottom of the board for the HC05 chip (your board should be a PU-7 and therefore this chip should be an 80-pin IC). Take a photo and show it here if you please? I should be able to tell if it is a genuine debug IC (this chip is the only difference between a retail and debug board, other than the obvious blue case and black sticky plastic around the output sockets).
Either way, it may well be that the CD-ROM RAM buffers are out, which explains why the disc will spin but you cannot boot anything. In which case you'd need to find another intact PU-7 board- possibly from an early SCPH-1000- and swap the HC05 chips over using a hot air station. I've used this technique before. Edit: you are looking for a square chip with an (M) Motorola logo on it, with a blue or yellow corner dot. The early PU-7 debug boards have this, but the retail versions instead have "Sony Computer Entertainment" printed on this chip. In which case someone has already pulled a switch on you.
 
Almost same issue with my green debug. Disc will loop spin between 1x and 2x indefinitely but never boot the game. Only audio CDs. Waiting for a better time to be able to repair it...
 
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