755 series TLA differences

vbimport
#1

I’d noticed a difference in the 12x P-CAV burn strategy between my 755 and 760 series drives some years back. The 755 drives would always do a speed drop in the CAV portion of the burn while the 760 drives would not. It’s easier to show than describe:

I’d just chalked it up to the differences between the two series of burners and didn’t factor in the TLA of the drives, which happen to be 00xx for the 755SAs I have but 01xx for all my 760 drives. I once had a TLA 01xx 755SA but I traded it for a 716SA long ago so I didn’t remember how it burned 12x. However I recently reacquired one this week and I discovered that it burns 12x P-CAV without the small speed drop:

So it would seem the change from TLA 00xx to 01xx, at least for the 755 series, altered the 12x P-CAV strategies to remove the little speed dip. Does anyone have a TLA 00xx 760 series drive to compare?

#2

I’ve never had a 755sa 01xx, so I can’t really compare (the “a” version never got to 01xx)

However I did notice the slowdown you describe with an “a” model but I was under the impression its occurrence lessened with later firmware. As for the 760a I do have 00xx and 01xx variants but the 01xx act as spares and I don’t really have extensive scans from them to create a valid comparison. I’ve never seen the slowdown either with 00xx or 01xx variants of the 760a.

AFAIK on the 760 the change from 00xx to 01xx went with a new laser pickup. Apparently the same as used in Liteons LH-20 series. I have no clue that changed on the 755sa from 00xx to 01xx.

One thing to remember is, that the 755 was the original 760 whose introduction was postponed because of quality problems with 18x writing. So the original 760 was relabeled 755 and an overhauled 760 was introduced later. There are some hardware differences between the 755 and 760:
http://ysscdr.web.fc2.com/px760a/px760a_bunkai.htm
It’s only my speculation but maybe these differencies where also responsible for the slowdown you describe? Perhaps some resonance in vibration that required a slowdown?
The 755SA was still produced when the 760A was already available. Maybe later models of the 755SA used the same parts as the 760. Could you look inside and check if the disc-holding table is of the same design as the 760 one?

#3

I’d be inclined to believe the theory that later 755-series drives were the same as 760s. In fact, the 755UF was known to actually contain 760A drives that had 755A firmware on them, as was the case with the 755UF I bought off ebay.