PC Engine Duo laser adjustment - Almost there! Help please!

[burn_654]

Hi there, loving the info on these forums!

I recently acquired a PC Engine Duo (not R or RX) with 'non-working' cd-rom for a good price and am trying to get it running.

Here's what I know:
-PC Engine Hucards work perfectly.
-All sounds (adpcm drums etc.) appear to work even from headphone port.
-Motor spins, it started off not playing cd games but occasionally played the first track of a music cd with stutter.
-There's no obvious sign of cap leakage, bursting, or fluid on the main board. I might have lucked out with that, but I won't rule it out.
-I'm using a music cd to test its capabilities. Seems pretty obvious to literally 'hear' when there's a problem. Games are not fully booting yet.
-I've removed the plastic housing cover over the cd assembly for kicks, no discernable changes.

Now here's where I came in. I followed the calibration guide (very nice) and did some adjustment on the pots. Now it reads the first couple tracks of a music cd flawlessly, no stutter. Progress! But it has trouble reading past say, track 6-7 on a 20 track cd. I heard that this might be V105's tweaking (spindle speed correction?), but I wasn't able to get a huge range of adjustment on it - basically I could get + or - one track to read. Depending on its position, I could read track 7 if I booted it up cold to that track but if I was skipping around, no dice. Which made me question if it could have something to do with the motor/rail mechanism - it looks like it slides in to seek, gets lost and gives a click or two, re-orients itself at the outer edge, and then back in the track position, ad nauseum.

Alright gurus, what can I try? I'm not going to rule out replacement parts (as much as I'd like to) but there's good signs of life even as is. Tips?

[BlueBMW]

If your caps are still original, they may be the culprit.  They affect sound most noticably but I've had several units have reading issues that were corrected by a cap change (all of them)

[burn_654]

Alright, sounds fair enough. I'm more than capable to do it, just a matter of time crunch lately.

Which ones are related to laser/cd assembly operation? I assume just the ones south of the cd assembly? I know from reading around that the common response is to 'replace all of them' but as far as I can tell the sound output is working great, nice and loud too. I'd rather not add another variable to this if I don't have to.

[BlueBMW]

I dont think we've tracked down all the specific ones directly related to the laser but i know the 3.3uf 50v is part of it.  Even if your sound is fine.. its still important to do them all preventatively. I have yet to see an original duo without a single cap leaking.  You probably wont see the leaked ones until you remove them.

[thesteve]

it could be focus related, as the later tracks require better focus control.

[esteban]

ASIDE: Welcome to the forums.

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