Turbo Duo CD player woes

[FABombjoy]

Well I finally get a Turbo Duo, and of course it would have to have some issues.

At first, it seemed to have an easier time loading Super CD games. It wouldn't really play all v2 games correctly, only v3. But, some v3.0 games don't behave correctly either.

If I turn the console upside-down & play a CD, it pretty much works OK with either type of CD game.

Any comments from the Duo-experienced? Does it sound more like a laser or like a transport issue?

HuCard port works fine. For kicks, I booted with the v2 system card. v2 games still wouldn't play properly.

[omnedon]

Have you tried tweaking the laser pot? Recording start settings and such? Is the disc transport fluttering at all?

[FABombjoy]

Have you tried tweaking the laser pot?

I've been holding off until I have a solid game plan together


Is the disc transport fluttering at all?

er... fluttering? I think it's twitterpated, but I don't know about any fluttering :D

When it has a tough time reading a disc, it does a lot of soft "ZZzzz... click... ZZzzz... click..." like it's refocusing, rehoming itself, or something of that nature. When I pop the CD top, the disc appears to be spinning true (no wobble). From what I can see through the teensy viewing window, there doesn't seem to be any wobble when the lid is down, either.

[omnedon]

It sounds isolated to the laser to me.

The key to pot tweaking with disc based systems is to record EVERYTHING. Test consistently, and take time. The temperature of the unit can make a good read setting go bad.

Avoid 'cranking' the pot, as the laser can be blown. Since you have some read functioning, the ideal setting is likely nearby, likely with a lower resistance, but it could conceivably be higher. 50ohm increments is usually plenty.

You also mentioned it seems to work better upside down. This indicates the height of the disc in relation to the laser may be helping. I doubt the Duo has a height adjuster, but it's worth a look.

I've never tweaked a Duo, so I don't have any ballpark settings to throw your way. It may not even work. But since that laser already can't focus for crap, you've little to lose.

record your settings. If it works, please please please share. :D

[FABombjoy]

I'll definitely post if I manage to fix it. It's only kinda flaky, so it's probably a focus or sled wear issue (like early model PSX). Trouble is that I bought it from eBay and I'm not sure what the seller is going to want to do. I'm hoping he'll cut a deal that's worth my time investigating & repairing it. I don't want to tear into it yet until I know for sure since I don't like to do gratis repairs. Naturally he's got the paranoia engine going since I basically emailed him saying "it's busted, but if you split the difference I'll keep and repair it myself".

Hopefully things are clearly marked and there are some test points inside that I can warm my scope up to. We'll see.

[FABombjoy]

Well, there's a big plastic pot on the sled near the laser ribbon cable. The only pot on the sled that I could see. A few clockwise increments & it started reading all discs properly.

At one point it seeked to the disc edge, crashed, and wouldn't return to center. I backed the pot off counterclockwise a tad, manually reset the laser to center & it's been working fine ever sense.

I still don't trust it, tho.

There are 5 pots on the board next to the CD player too... VR101-VR105. I sure would like to know what they're for. The chips nearby are all, of course, unsupported parts and I can't find a datasheet on all but one of them so I can't trace out what the pots are for. I'd prefer to scope it out and adjust it properly, but this'll do in the mean time. I'll just use my TG16 CD for v2 discs, and the Duo for v3 discs.

[omnedon]

That's the problem with a scopeless 'blind' adjust. Keep your recorded settings. In my experience, the lasers do seem tolerant of these 'tweaks', but it would not surprise me in the least to find a proper adjustment was more of a balancing act between the pot you tweaked, and one or two of the others as well.

The simple resistance decrease may be like changing tire inflation when your shocks are bad. A half-ass fix.

It's tough when we don't know the test points and specifics.