"Side effects" of connecting a drive on an external box

Hi :slight_smile:

Recently I noticed a really strange “side effect” on drives when I install them on an external box. Disc quality, both in burning and in reading, deteriorate badly.

Actually I don’t know if this behaviour is due to a software or a hardware issue, but because of I noticed it with different drives in the same external box it seems to me a hardware problem, so I posted here in hardware forum.

The box I’m using is this one. It have a NEC chipset (sorry, I don’t have a camera, so I can’t take a pic of the chip :frowning: )

The following are some examples of this strange behaviour. This disc was burned @12x with a Samsung SH-S182D firmware SB04. The first pic is a scan done with liteon 1693 in the external box, the second is a scan of the same disc with the 1693 installed internally. The third pic is a scan done with a Sony 120 installed internally, just to have a comparison.

The last pic is a TRT.

I wonder if it’s only me or someone have this same quality worsening when the drive is installed on a box.

I had the same issues, but I never posted about the, :confused: or I did and u missed the thread :open_mouth: But yeah, I tried two different chipsets and i thought it was the batch and sent two +r 100 packsof TY back, for -r, then got my rig and realised it was the lameass cases.

oops :o I missed your thread

However I wonder why the box can create so big differences :frowning:

The short answer is that it cannot. I’d like to see a WRITE test done on the external box to see if there are buffer under-runs occurring. That’s about the only thing that could have a direct impact on burn quality.

The other possibilities in a external box are heat and power. Heat can affect burn quality to some extent, power issues are less likely. But as far as the drive electronics go, a burner doesn’t know if it’s an external box or not, so burn quality cannot be affected directly.

There’s a lot of possible variables here, don’t assume that just one of them is the cause.

If I understand this correctly, the three scans and the TRT are of exactly the same disc (burned in another drive), and the two first scans are in exactly the same 1693S drive but mounted externally and internally?

A drive can show much worse scans when it heats up after performing multiple burns/scans/reads. Could the first scan above in the externally mounted 1693S be the result of a drive being really hot after doing a lot of work, while the second scan is in a cool drive?

I suppose an inadequate power supply for the externally mounted drive could also contribute, although that is merely a hypothesis and not based on any experience with insufficient power supplies.

I suppose it’s also possible that you can get scanning differences due to excessive vibrations in the disc and drive, and vibrations could be significantly different depending on how and where the drive is mounted. Since the scans are done at only 4x this doesn’t seem very likely.

This is mostly conjecture I’m afraid, but the part about scans becoming worse when the drive is overheating is real enough, but it might not be the right explanation or only part of the explanation.

I use an external USB enclosure box from ADS, and whenever I plug a hard drive to it, it works excellent, with sustained 35MB/s transfer, however when I plug an optical I get the same effects as you - I thnk those enclosures are optimised for hard drives, either that or it’s an issue with the IDE to USB chipset - NEC ? Yes same chipset used on my ADS box.

Yes, this is correct :slight_smile:
And both discs was checked with the drive cool, i.e. the disc scanning was the first thing I did with the drive after powering on the computer (no previous burnings or disc readings).

Thanks for your answers :slight_smile:

@CDan: I’ll do some burnings as soon as possible using discs on the same box of that one and I’ll post results here :slight_smile:

Regarding power supply, too bad I have not enough knowledge in electronics to check it :frowning:

I really have no idea how to do this :o

its got nothing to do with the buffer. I’ve ran an 8x burn in the box and in the pc, and its pretty clear theres write quality differences. I would get up to a level of 8 PIF as opposed to 3 or 4 so its there.

AFAIC, its down to the chipset or vibrations. Temps shouldnt be an issue, and nor should power. :confused:

A chipset in an external box cannot affect burn quality. It’s physically impossible. It could theoretically affect scan results though, if you’re scanning on a drive in the box.

I wouldn’t exclude anything with this home-scanning thing. I’m seeing differences just changing IDE drivers.

Try that external scan again. The last half of the scan looks okay.

I often get scans that start out with excessive errors and then they taper down. I’ve not seen any as bad as yours, but the PIE graph has the same shape. When I scan on newer drives I can see the jitter is abnormally high.

My Yuden T02 can do this because the jitter is always highest at the beginning and tapers off. Excessive jitter because of a badly loaded disc or a hot disc will then cause more errors at the beginning. An eject and re-load sometimes fixes it.