Adjusting PS1 laser (7500 series)?

[thebigcheese]

I am fairly certain that my laser either needs some adjustment or just to be replaced (hopefully not), but I'm having trouble finding good info on how to adjust it, especially for the 7500 series (or later) which only have the single adjustment pot. Most of the guides say to use an oscilloscope, but I am really hoping I can get in the ballpark without dropping $100+ on one (not to mention figuring out how to use it). I tried following this guide, but I'm not sure where they are getting the numbers from and adjusting the one pot I have to match the 11.4 mV number they present didn't do much (if anything): http://dogbreath.de/PS1/LaserAlignment/Laser.html. I've also looked at several YouTube videos, including the GadgetUK one, but in all these videos they just point to which test point to use rather than saying the label for that test point, so it's hard to translate what they are doing to my model. So here are my questions, followed by some background to describe why I think the laser needs adjusting:

-Can I do this with a multimeter or is an oscilloscope an absolute must?
-Which test point(s) should I be using? This service guide is for my model: https://www.retromodwiki.com/images/2/2 ... matics.pdf. Test points are described on the last page. I think I'm supposed to be using CL704 for the RF level since that shows the graph as it looks on an oscilloscope (as I've seen in the videos), but most people talk about the tracking height of the laser and that is checked at CL709.

Background:
Originally I was just going to use a PS2 to play PS1 games, but I saw that it is completely incompatible with some games and has issues with others, including SotN, a personal favorite. SotN is really where the issues are. I've got a pretty clean copy of the game that I've had resurfaced (by a place I trust) twice now to the point where it has only the tiniest of little scuffs. There are no deep gouges, no pitting, no disc rot. I have discs that look 5x worse but run with no issues. The game is a black disc if that makes any difference. However, this particular game has a bad tendency to have audio skips, particularly on certain tracks. Since it's really only this game, I initially thought it was the disc, but, given what I said above and the fact that it runs with no (audio) issues on the PS2, I am inclined to think it is the laser. Further bolstering that thought is the fact that this is now the third or fourth PS1 I've tested this specific disc with and the amount of skipping was different with every console. This PS1 is the one that had the least skipping, so that's why I kept it. But I'd really like to get rid of the last bits of skipping so I can enjoy SotN properly.

[nmalinoski]

So I take it the actual problem is that your PS1 is having difficulty reading discs?

I think adjusting these lasers is like adjusting any other laser, like those in the GD-ROM. I believe you can use a multimeter, but you're supposed to measure the resistance across the pot before you start so that you'll be able to return it to its original state and start over if needed. I made that mistake trying to blindly adjust the pot on my GD-ROM and just gave up.

Adjusting the laser is a time-consuming, frustrating, trial-and-error process--it's not as simple as just giving the pot a tweak--and, frankly, I didn't find it was worth my time; so, when I was restoring my brother's SCPH-5501, I ended up just buying a new optical drive unit, specifically a KSM-440BAM, which was used in the latter PSones. I specifically bought one of the totalconsole-branded units, as those come with a flex cable extension for installation in the older, larger PlayStations. Looks like they're about $40 from totalconsole directly (excluding shipping) or $50 and Prime-eligible from Amazon.

If you track down the drive from a different vendor, it may not have the flex cable, in which case you're going to have to either track that down separately or pick up a second-hand PSone to toss the drive into to play your games.

[Kez]

Seems to me like the common factor here is a single CD which has undergone resurfacing twice. I know SOTN is a rare game so it's not exactly easy to find another copy.. but it might just be the disc has issues which do not manifest with the (much faster?) PS2 laser.

[thebigcheese]

Seems to me like the common factor here is a single CD which has undergone resurfacing twice. I know SOTN is a rare game so it's not exactly easy to find another copy.. but it might just be the disc has issues which do not manifest with the (much faster?) PS2 laser.

But would this not indicate that it is intrinsically a laser problem? The surface of the disc is practically flawless at this point. Like I said above, while it does seem like it ought to be a problem with the disc, it just doesn't seem like it possibly can be. It was pretty clean before I got it resurfaced, it's just that it was skipping and I wanted to narrow down the possibilities. And, again, given that the amount of skipping even varies from one PS1 to the next suggests that it is not the disc. In fact, the exact same track might skip sometimes and not other times even on the same PS1, so it's not even a consistent issue. Which says to me that the data is definitely there, the laser is just having trouble reading it sometimes.

Regarding the PSOne lasers, one of the other units I compared with was a PSOne, actually, and this one performed better. The PS1 I have also uses the nicer, later-model laser, though. To be clear, I haven't really had any issues with other games and in fact I can play through SotN just fine, it is just the audio that skips in places. If a new laser will help, I'm happy to get one, it's just annoying because they cost as much as buying another PS1 at this point...

[nmalinoski]

If a new laser will help, I'm happy to get one, it's just annoying because they cost as much as buying another PS1 at this point...

While this is true, chances are you'll be spending $40-$50 on a new PS1 that also needs a new laser.

[Kez]

Well my thinking is that maybe the disc has some minor issues that sometimes force the CD-ROM drive to take another pass at reading it, resulting in a skip when it briefly runs out of data to stream. The PS2 has a much faster CD read speed, so perhaps it is able to perform a re-read before the cached audio runs out and a skip occurs.

Obviously not a certainty, but it seems unlikely that you would have a very similar problem on 4 consoles that is limited to only a single disc.

[Syntax]

I have a multimeter and a scope but I tune my PS1 lasers a little different to everyone else.

I put THPS2 in or Tekken.

THPS2 streams the intro from the very outside of the disc where there is the most wobble.

Yeah the cheap laser replacements wobble discs or have off centre spindles, you have to sort that and the loose tray mech first with your original parts.

But yeah load up THPS2 with the lid off and something jammed in the lid switch, start listening to Rage Against the Machine and turn the pot until nothing skips. (Audio and FMV)
Then when your happy load Tekken and listen to an ingame stream background music for 5 mins.


Also keep in mind chipped PS1s will stutter with some out of region content unless you dual crystal mod it.

[thebigcheese]

I have a multimeter and a scope but I tune my PS1 lasers a little different to everyone else.

I put THPS2 in or Tekken.

THPS2 streams the intro from the very outside of the disc where there is the most wobble.

Yeah the cheap laser replacements wobble discs or have off centre spindles, you have to sort that and the loose tray mech first with your original parts.

But yeah load up THPS2 with the lid off and something jammed in the lid switch, start listening to Rage Against the Machine and turn the pot until nothing skips. (Audio and FMV)
Then when your happy load Tekken and listen to an ingame stream background music for 5 mins.


Also keep in mind chipped PS1s will stutter with some out of region content unless you dual crystal mod it.

I've not done any mods to mine, so nothing of that nature should be causing issues. I've been thinking about doing it similarly, loading up SotN to the area that keeps skipping and then tweak until it stops. Just a bit of a pain given where things are located but I might try that. I suspect that those tracks are located toward the edge of the disc as they are toward the end of the game (well, the normal castle, anyway). Not that that means they would be out there necessarily, but the increased wobble makes sense. If I can find a copy of THPS2 I might try that, otherwise maybe just load up an audio CD and run it out to the last track.

[Syntax]

Anything that streams from close to the outside is best to tune to as they are worse case scenario reads.

[thebigcheese]

I'll give that a go then, thanks. As a side note, I notice that SotN is one of the few games that uses XA audio. Causes different issues with the PSIO, but I wonder if it's just that games that use XA audio are more prone to read errors like this. My wife mentioned that she recalled SotN skipping on her back when it came out, though perhaps not to this degree, so who knows.

[evil_ash_xero]

I've had so much pain with PSX lasers.

[rama]

The main issue with PSX drives is that the plastic rails for the read head wear out, and do so in an uneven way.
Depending on the work hours the drive had, the read head will slant and make it harder for the optics to focus on the data.

If you go in and increase the laser diode power (turning the pot), the optics will be able to focus better.
This is a small band aid at best though, and will not last long (if even successful).

A better repair would involve leveling the read head again, and that means adding back the material that was lost due to friction.
People have used aluminium foil sheets and such in the past. It's very hard to get right.

So this is the problem, and I'd recommend getting a replacement drive, since it's just so hard to properly repair the frame.

The pictures down on this page illustrate it nicely (though only mentioning the wear on the read head, not the rails as well):
http://miked50.tripod.com/repair.htm

[thebigcheese]

The main issue with PSX drives is that the plastic rails for the read head wear out, and do so in an uneven way.
Depending on the work hours the drive had, the read head will slant and make it harder for the optics to focus on the data.

If you go in and increase the laser diode power (turning the pot), the optics will be able to focus better.
This is a small band aid at best though, and will not last long (if even successful).

A better repair would involve leveling the read head again, and that means adding back the material that was lost due to friction.
People have used aluminium foil sheets and such in the past. It's very hard to get right.

So this is the problem, and I'd recommend getting a replacement drive, since it's just so hard to properly repair the frame.

The pictures down on this page illustrate it nicely (though only mentioning the wear on the read head, not the rails as well):
http://miked50.tripod.com/repair.htm

I thought that was just the earlier systems? I've got one of the later ones with the metal parts, I believe.

[rama]

All PSX drives suffer from this.
The later drives wear down their silicone standoff stubs and the rails.
The first drives wear down the plastic that's shown on the repair page.
Sony never really fixed this issue, they just made it a little better :/

[Syntax]

If you can find a ps0NE cheap with a working laser grab it.
Those drives work extreamly well and only need an extension cable to work on other ps1

[rama]

Called Nylon in this page (might be correct, idk :p):
https://en.wikipedia.org/wiki/File:Play ... Pickup.jpg

It's easy to see how the all metal read head does not address the friction + wear down issue.

It's also on the other (hookup) side, by the way.
Oddly enough, even the metal there caves in over time.

Edit:
Here's the problem spots marked. The metal one is already showing the groove.

[thebigcheese]

Hmmm, so I tried out an audio CD that isn't super scratched but also isn't super clean, either, and I get no skips there. I do notice that there actually is some scratching on the very edge of my SotN disc, so maybe that's it? Going to try to borrow a friend's copy (if he can find it) and compare, maybe it really is my disc after all.

[thebigcheese]

Alright, had the local shop resurface it again. It is now virtually flawless, certainly at least as clean as any other game I own. And yet... still skips at the same point. I popped it in the PS2 for verification and I must not have played it very much before because it's actually worse on the PS2. The audio track starts by skipping, then completely cuts out. On top of that, can't even go to the start menu after that happens. So I guess it's definitely the disc. Sucks cuz that is not a cheap game (for my budget), but such is the way. Hopefully they figure out XA audio on the PSIO, then I can pick one of those up.

[rama]

I have a copy of Ehrgeiz (PAL) that had just a minor looking scratch on it.
It went through several runs in the resurfacing machine, but kept stop loading in the same spot.
After yet another run though, it started working.

The scratch wasn't all that bad looking even. Just very deep.

Maybe you can get a few more runs done

[thebigcheese]

I took a closer look up to the light, I think there is some disc rot after all. Much harder to see on the black disc. Sucks, but I guess that's what it is