SAMSUNG HT-Z Plays DVDs but not CDs, Why?

[Old Sparky]

I was asked to find out why the above Home Cinema Player wasn't reading discs, and, upon taking it apart, and cleaning the Laser Lens, it now plays DVDs without any problem, at least as far as pre-recorded ones go, but will not read CDs, three different ones having been tried. According to it's instruction manual, it's supposed to play single & double sided DVDs, DIVX discs, and audio CDs. Would this indicate a faulty laser by any chance. I would have thought this more likely to read CDs ok, but not DVDs, but may be wrong.

[Mark Hennessy]

Different laser for CDs - different wavelengths... It's entirely possible that the CD laser has a problem but the DVD laser remains working.

[Refugee]

I have a DVD player that will only play shop bought discs so it is absolutely useless for CDRs.

[Old Sparky]

Different laser for CDs - different wavelengths... It's entirely possible that the CD laser has a problem but the DVD laser remains working.

Mark - As far s I know there is only one lasr in this machine, or at any rate on;y one laser lens, which I cleaned, although I haven't checked any individual diodes on the Pickup assembly, nor yet checked price/availability of a replacement Pickup assembly.

[Old Sparky]

I have a DVD player that will only play shop bought discs so it is absolutely useless for CDRs.

The three CDs I've tried so far are all commercially recorded discs, although one was a Freebie with 'Vintage Rock' magazine. The manual states that the machine should play both 3.5 & 5" CDs, but makes no mention of CD-R or RW discs.

[Refugee]

Some do play -R and -R/W discs even if the handbook says nothing. I think the culprits are one or two branded models where the manufacturers have been approached bu the record companies.

[Mark Hennessy]

Different laser for CDs - different wavelengths... It's entirely possible that the CD laser has a problem but the DVD laser remains working.

Mark - As far s I know there is only one lasr in this machine, or at any rate on;y one laser lens, which I cleaned, although I haven't checked any individual diodes on the Pickup assembly, nor yet checked price/availability of a replacement Pickup assembly.

Of course I might be wrong about this specific machine, but based on my experience of DVD players, there will be two separate laser emitter diodes (650nm and 780nm). You won't be able to tell from a quick look, as they are buried deep inside the mechanism. There is only one lens visible from the top. On the Sony machines I own, you can display the hours of use of both lasers in service mode.

Failure of one diode only does happen. Of course, there is separate drive circuitry for each laser diode, so there could be a fault there. Or a poor connection somewhere that isn't carrying the drive current to the diode. Or the CD-specific servos could be out of alignment. But going deeper requires a service manual - a 30 second Google didn't seem terribly promising, but you have more of an incentive to search more thoroughly that I did...

Good luck,

Mark

[Old Sparky]

Thanks, mark. I may look for service info for this machine ( Full model no. HT-Z310 ).