This article is from the CD-Recordable FAQ, by Andy McFadden (firstname.lastname@example.org) with numerous contributions by others.
This seems to happen on Philips CDD2000-based units, such as the HP4020i,
usually a short while after the warranty runs out. The most common cause
is a spring that weakens with age, but it might also be due to lubrication
breakdown. After a while, the recorder starts failing when trying to write
beyond a certain point on the disc.
The ways of dealing with this range from minor system changes to the
placement of chicken entrails on selected components. Reducing the DMA
rate on the AdvanSys SCSI card (for the HP4020i) may help, buying better
SCSI cables and checking for proper termination may make a difference, or
even powering off and on again right before the burn. For some users,
however, the problem is mechanical rather than spiritual.
One user was told by Philips tech support that if error 50h (write append)
occurs, it means the drive has to be returned to the repair center. Other
users have been told that the error can occur when attempting to write an
empty directory or zero-length file. Under Easy-CD Pro '95, this is
reported as error 171-00-50-00 (see the Roxio web site for a complete
list of error codes).
If the fault is caused by the worn spring, it may be possible to fix the
problem by replacing the spring. This will definitely void your warranty,
and you shouldn't even think about trying this unless the only alternative
is to throw the drive away. Jonathan Oei posted some details about the
process (search for comp.publish.cdrom.hardware, subject "CDD2000 & Spring
Fix", on http://groups.google.com/), and a detailed description of the
procedure can be found on http://www.fadden.com/doc/fix-hp4020i.txt.
This procedure requires some special tools (mini torx drivers and really
fine jeweller's pliers), and involves disassembling much of the drive. If
you open up the drive and remove the circuit boards, you will see that the
laser writing assembly is moved by a DC stepper motor. The motor has a
plastic drive gear that is meshed with a plastic "rack" on the laser. The
spring in question is a piece of wire that pushes the rack against the
drive gear, so when it weakens the gear slips and the write fails.
Replacing the 0.012" wire with a 0.02" diameter wire solves the problem.
The high temperature in the drive may contribute to the breakdown of the
lubricants that allow the laser head to travel. You may be able to prevent
the situation by installing a fan.
This question is also covered in the HP4020i FAQ, available at