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Apple CD SC - Not reading disks properly??


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#21 techknight

techknight
  • 68LC040

Posted 13 January 2017 - 01:51 AM

Eh.. never owned any titles or players. So I never cared. Just never got interested, although it was used alot when I was in school and I liked the picture quality better than VHS IMHO. 

 

I know a couple media format collectors, and seen a few on youtube. owning CED, and all that good stuff.

 

But thats just not me. However, I am more addicted to VFD displays of all things. 


Edited by techknight, 13 January 2017 - 01:52 AM.

Main PC: Intel core I7 920, MSI x58 platinum, Radeon4850
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#22 apm

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  • 6502

Posted 13 July 2017 - 10:52 PM

Resurrecting this thread to ask about a closely related set of symptoms: I have two Quadra 650's that each came with an internal CD drive (Sony CDU561-25), each of which has different problems.

 

Drive #1: about 80% of the time, it ejects the caddy immediately after putting it in. If it does keep the disc in, it reads it normally without errors, but sometimes spontaneously ejects it several minutes later (whether active or idle at the time).

 

Drive #2: when I got it, it would load the disc but generated frequent read errors and very slow data rates (probably retries). Now I just hear seeking noises while I get a spinning cursor, and after a few minutes I'll get a "disc unreadable" message.

 

My first thought was bad caps, and actually the boards are quite a mess of cap goo. I've recapped and thoroughly cleaned one board (not the other yet). But here's the funny part: both problems above follow the drive mechanisms, not the PCBs. Each drive will behave the same whether it's got the recapped board or the non-recapped one.

 

Earlier in this thread, techknight says that weak optics might cause the eject issue. I've cleaned the lens with alcohol on Drive #1. It still ejects discs 80% of the time but I haven't seen a spontaneous eject after the disc was loaded. I haven't tested Drive #2 again yet.

 

What else should I be checking? Are there other parts under the lens to clean, and if so, how do I get at them without damaging the mechanism?



#23 CelGen

CelGen
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  • LocationKamloops, Canada

Posted 14 July 2017 - 04:49 AM

Perhaps the eject switch is sticking?



#24 apm

apm
  • 6502

Posted 14 July 2017 - 09:07 PM

I don't think there's a physical eject switch on these drives. I suppose it could have something to do with the caddy not going in far enough. At first, it would never go in far enough for the "caddy loaded" flap to come down. Now that flap comes down all on its own (?). I haven't yet figured out all the little moving parts in these things!

 

Meanwhile, cleaning the lens doesn't make much difference on the other drive either. It does read discs sometimes now, but slowly and unreliably, as it originally did. So it's still a mystery what part of the mechanism might cause either of these problems.



#25 TimHD

TimHD
  • 6502
  • LocationSydney, Australia

Posted 14 July 2017 - 11:26 PM

Drive #1: about 80% of the time, it ejects the caddy immediately after putting it in. If it does keep the disc in, it reads it normally without errors, but sometimes spontaneously ejects it several minutes later (whether active or idle at the time).

I had a similar issue with my CD SC and it turned out to be CD format related. Basically the larger 700MB formatted CD-Roms or CD-Rs did not read (CD-RW never work on some!), but I found that earlier Apple CD-Roms  that came with both MacOs 7-9 and Mac OS X formats, loaded ok and did not eject immediately. Can't recall which of those grey Mac CD's it was, but I recall it was a real early disk (maybe a Airport CD Install disk or something?). I then found some commentary that suggested that these earlier Caddy CD drives came out when 650MB CDs were the thing and thus can't read the newer/faster/larger CDs. That said, seeing it reads ok then ejects, sounds like optics or wiring (heating up, separating)?


Mac SE/30, IIfx, IIsi, Quadra 630CD, 5200/225 DE (Black), CC (Mystic), iMac DV G3, iMac G4 (USB 2.0), G4 Cube, MBA 13", iMac 5K


#26 techknight

techknight
  • 68LC040

Posted 15 July 2017 - 06:19 PM

its hard to say without physically seeing the drives and putting a scope on them, but again it still sounds like optics. Mainly a weak laser diode. Turning up the current limit potentiometer on the side of the pickup assembly should bring it up back to normal operating conditions, but its temporary as it WILL accelerate the wear on the diode. 

 

the only solution is to change the diode with a new one without losing the optical alignment (very hard to do). In more rare cases, the bonding agents in the optical prism assembly that polarize and route the beam, tend to break down and turn foggy blocking the diode emission. 


Edited by techknight, 15 July 2017 - 06:20 PM.

Main PC: Intel core I7 920, MSI x58 platinum, Radeon4850
PB: tibook G4, ibook G4, ibook g3x2, Lombard, 160, 165, 180, 180c Duo 2300x2, Duo 270c x2, 520cPPC, 3400c, 1400c
Desktop: G3AIO, SE, SE/30, 512k, plus, LCIII, iMac G4, iMac intel, 6400/225

#27 apm

apm
  • 6502

Posted 15 July 2017 - 07:05 PM

I can try that. The main question is how to get the thing apart! The diode is inside a big black case with the lens on a spring-loaded mounting near the front. I presume it's a little voice coil motor in there to micro-align the lens to the track. I was hesitant to start pulling the thing apart without being sure it would go back together again.

 

Any idea what the trimpots on the main PCB do?



#28 techknight

techknight
  • 68LC040

Posted 22 July 2017 - 12:33 AM

the optical pickup assembly contains the "lens". and it has a worm gear which is the sled motor. there is a micro potentiometer on the optical pickup assembly itself. 

 

The pots on the PCB are usually Focus and Tracking offset, PLL lock, etc... 


Main PC: Intel core I7 920, MSI x58 platinum, Radeon4850
PB: tibook G4, ibook G4, ibook g3x2, Lombard, 160, 165, 180, 180c Duo 2300x2, Duo 270c x2, 520cPPC, 3400c, 1400c
Desktop: G3AIO, SE, SE/30, 512k, plus, LCIII, iMac G4, iMac intel, 6400/225




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