CD-player erratic with CD-Rs
 

This unit, TEAC PD-D850, is having difficulties playing audio CD-Rs. Not
every CD-R has
problems, only some of them and the problem consists in not locking into the
tracks. The strange thing is that the CD-Rs are all of the same brand, same
manufacturing date and even from the same canister!(TDK 48X, 80min). I
opened the unit thinking that perhaps the signal gain need to be slightly
adjusted. I found 4 potentiometers called:
1. T-OFFSET
2. T-GAIN
3. E F/BAL
4. FREERUN
I tried to adjust them with no avail. Any leads? What is the difference in
the signal between a normal CD and a CD-R?
Thank you very much,
Gene

CD-player erratic with CD-Rs
 

"EpsilonRho" wrote in message
t...
This unit, TEAC PD-D850, is having difficulties playing audio CD-Rs. Not
every CD-R has
problems, only some of them and the problem consists in not locking into
the
tracks. The strange thing is that the CD-Rs are all of the same brand,
same
manufacturing date and even from the same canister!(TDK 48X, 80min). I
opened the unit thinking that perhaps the signal gain need to be slightly
adjusted. I found 4 potentiometers called:
1. T-OFFSET
2. T-GAIN
3. E F/BAL
4. FREERUN
I tried to adjust them with no avail. Any leads? What is the difference in
the signal between a normal CD and a CD-R?
Thank you very much,
Gene

The difference between a burnt CD, and a pressed one, is the reflectivity.
Some players, particularly those not specifically specced to play recordable
discs, have always struggled with them, and the problem becomes more
pronounced, as the laser wears.

Unless you really know what you are doing, you must not indulge in pot
twiddling. Some adjustments, particularly E-F balance and VCO ( your
"Freerun"??) are especially critical, and if you get both of them adjusted
even slightly wrongly, your problems will be compounded, and may start
extending into playability issues with pressed discs, as well.

Many Teacs use very 'bog standard' general quality Sony lasers from the
"KSS" series, and these have never been particularly renowned for their
ability to cope with home burns. If turning up the tracking gain ("T-GAIN")
pot did not at least make the problem better, and the lens is clean, then
you probably need to consider replacing the laser. Do not be tempted to up
the laser output power, by twiddling the pot on the laser's connector board.
If the laser is at all marginal, then doing this will speed its demise like
you wouldn't believe.

Meat's suggestion of reducing the burn speed is also a good one. You might
also like to try a disc burnt on a different drive, or using different
software, and you might also like to try a different manufacturer's disc.
Some lasers prefer the purple dye and some the green or goldy coloured
discs. A 'good name' disc is not always the best for all players. I have had
great success with one of the major UK supermarket's cheap and cheerful 'own
brands', for instance.

Arfa

CD-player erratic with CD-Rs
 

"EpsilonRho" wrote in message
t...
This unit, TEAC PD-D850, is having difficulties playing audio CD-Rs. Not
every CD-R has
problems, only some of them and the problem consists in not locking into
the
tracks. The strange thing is that the CD-Rs are all of the same brand,
same
manufacturing date and even from the same canister!(TDK 48X, 80min). I
opened the unit thinking that perhaps the signal gain need to be slightly
adjusted. I found 4 potentiometers called:
1. T-OFFSET
2. T-GAIN
3. E F/BAL
4. FREERUN
I tried to adjust them with no avail. Any leads? What is the difference in
the signal between a normal CD and a CD-R?
Thank you very much,
Gene



CD-Rs have a variety of differences, in a nutshell they're more difficult to
read. If you fiddled with those pots, the CD player may well now be
misaligned to the extent that it will never work very well again.

CD-player erratic with CD-Rs
 

Thank you all for the reply. I'm an electronic engineer, so I am aware of
the pot adjustment issue. Before playing with them I marked their positions
with a fine line of white paint. The main question is if typically there is
a pot that sets the gain of the laser preamp (I would exclude an increase in
laser output). A cursory look at the printed circuit board failed to reveal
such pot.
Thanks, Gene

CD-player erratic with CD-Rs
 

"EpsilonRho" wrote in message
t...

Thank you all for the reply. I'm an electronic engineer, so I am aware of
the pot adjustment issue. Before playing with them I marked their
positions
with a fine line of white paint. The main question is if typically there
is
a pot that sets the gain of the laser preamp (I would exclude an increase
in
laser output). A cursory look at the printed circuit board failed to
reveal
such pot.
Thanks, Gene



There will not be. 'Standard' commercial designs have never had one. You are
actually lucky to have the pots that you mentioned ! For some years now,
most designs have had no physical adjustments at all ...

Can you see what laser type it uses ? It's usually on a little sticker on
the laser connection PCB.

Arfa