Strange undetected file error with DW1640

vbimport
#1

Hi all,

I have a DW1640 for a few months connected to my computer through a USB2.0 external case. Everything was working OK, except for some few coasters I made (with detected CRC read error, unreadable disk, …)

I am used to check the DVDs/CDs I burn, with a global file compare program. For the first time today, I got an error comparing one big binary file on the DVD ISO and the original one on my hard drive. It was a “one bit” error, somewhere in the file: a 0xD5 was on the DVD, instead of a 0xD4. I burned again the whole ISO (it was on a DVD+RW, already used several times) and no error this time.

What I find very strange is that when there is something wrong when burning a CD/DVD, it is detected by the CRC checks and give a nice “unable to read file due to cyclic redondancy check error” and you cannot read the file. This time it looks that the CRC written on the DVD was already computed by the drive with the error in the file…

So is this kind of “undetected error” (unless you compare the files bit per bit) expectable from a DVD burner? Where did the error appear : In the USB interface ? In the burner ? In the computer ? (for the last one, I haven’t got any error like that at all, while transferring GBytes of data, memory modules are fully tested, …), or even in the CD/DVD burning software (Nero) ?

Thanks in advance for the tips,

Stellar7.
#2

Stellar7, welcome to the forum! :slight_smile:

Is this kind of undetected error expectable? No it isn’t!

A single undetected bit-error is theoretically impossible in a CRC, so that single bit must have been flipped before the CRC was calculated. (Multiple simultanous bit-errors are possible but not a single bit-error).

It can be extremely hard to pin-point where the problem happened - especially if it only happened once.

If you are running an overclocked system, I would start by disabling the overclocking.

Check your memory (again) with a memory testing program such as e.g. memtest86 or Microsoft Windows Memory Diagnostic, then check that the IDE cable inside your USB case is properly attached.

#3

Hello DrageMester,

Thanks for the welcome! It is true that even if I registered in May 2005, it took me one year (May 2006) before writing my first message :wink:

Regarding the issue, I have checked the cables (USB cable, IDE cable inside USB case), and I don’t use any overclocking. Memtest was extensively run when I bought the memory modules, and also a few weeks ago.

I know it’s hard to find out where the bit swap occured, but I wonder if it could have happened in the DW1640. The USB case is not very well cooled, and drive is quite hot after a few burns, which was the case here. Could it be a firmware error, or a drive memory error due to overheating?

Stellar7.

#4

Oops, I didn’t notice that you joined in 2005. :o

Congratulations on your first posts then! :slight_smile:

In theory this could explain it, but it’s probably not a firmware bug or more people would be seeing it.

Unless this problem happens again, which we both hope it doesn’t, then you may never find out exactly why it happened.