Hi all,
I have an Onkyo dx-6750 integra cd player, which I purcased as
defective. I cleaned it and set it up with an oscilloscope, the
transport is perfect now. Nice eye pattern, nice TE and FE signals,
seeks fast, no skipping, no problems at all, nice sound - but with
original cds only. When I try to play a cd-r disc, the transport still
reads perfectly but the sound is distorted. If I take a look at the
audio signal with the scope I see a somewhat "stepped" signal.
Now, I just can't see if it's the transport or the digital circuits
causing the problem. It's unlikely the transport because there are no
signs of any difficulties with reading the data. And it's unlikely the
digital circuits because once the data is read off of the disc I can't
see how the rest of the circuits can make difference between different
discs.
Any ideas?
m127

wrote:
Hi all,
I have an Onkyo dx-6750 integra cd player, which I purcased as
defective. I cleaned it and set it up with an oscilloscope, the
transport is perfect now. Nice eye pattern, nice TE and FE signals,
seeks fast, no skipping, no problems at all, nice sound - but with
original cds only. When I try to play a cd-r disc, the transport still
reads perfectly but the sound is distorted. If I take a look at the
audio signal with the scope I see a somewhat "stepped" signal.
Now, I just can't see if it's the transport or the digital circuits
causing the problem. It's unlikely the transport because there are no
signs of any difficulties with reading the data. And it's unlikely the
digital circuits because once the data is read off of the disc I can't
see how the rest of the circuits can make difference between different
discs.
Any ideas?
m127

Sometimes it makes a difference what speed the CD-R was recorded at. (12X,
24X, etc) You could try CD-R's which were recorded at a lower speed and see
if that makes a difference.

I have found this to be especially true of players which are Philips based.
Since your model is not listed in my American Onkyo servicers' website, I am
unable to examine the technical data.


Mark Z.

P.S.

There are some "silver" CD-R's you could try.

There may not be anything you can do to get it to play your existing CD-R's.


Mark Z.

Oh I see! I just thought that if it had a serious problem with those
discs it would not play them at all but mute or stop. The
unbelieveable thing was that it played, but distorted.
Anyway, I have a nice little bunch of cd-players, some good ones also,
like a Teac VRDS-10SE, a Teac CD-5, a better Onkyo (DX-6870), two
Denons (dcd-755 and 1450), a B&O Beogram etc, so this Onkyo DX-6750 is
to be for sale soon anyway. I just wondered if I could do anything to
make it better and to sell it better.

Another good idea is to keep it as a parts backup for my DX-6870 since
the mechanical parts are the same.
The interesting thin is that the 6870 doesn't have the problem the
6750 has. They have the same transport. I still find it a very
interesting question if the transport or other parts are the origin of
the cd-r distortion problem.

try recording a cdr with another computer

could be the sampling freq on the sound card in your pc or the servo
speed on your cd burner is just a little out of range for the player

did you try tweaking the FE and TE loops when the CD-R is playing?

Mark

Hi Mark,

Yes, I tried playing with Focus and Tracking, using a scope and
listening to the sound. I didn't manage to take out the distortion,
and now the servos are set at the best possible.
I think my writer is OK, it's a very good plextor, writes crazy good
discs that can be played on anything all over the world. I also played
some discs written by others, and the distortion is still there.
Anyway, I want to sell this player sooner or later, so it's not my
discs that are the problem, I just wanted the player to be able to
play more discs than it plays now.
Someone somewhere told me that the origin of the problem can be the
error correction, he said the player may have c2 errors with cd-r and
leaves out some samples while playing back. Well, I don't know. I'm
not that good in error correction and cannot monitor how many errors
the player has got (and if it differs with different discs).

try asking on rec.audio.pro
Mark