I have downloaded the brochure (Vinylengine, I think) re. the original 1x00 series DD tables. The SL 1900/2000 was the cheap table (the SL 2000 is manual) "designed for those who want direct drive performance at a moderate cost". The tonearm is shorter- 22 cm compared with 23 cm for the better models (SL 16/7/800). Rumble is -45/-70 for the SL 2000 compared with -50/-73 on the better models. Wow and flutter are 0.045 WRMS versus 0.025. The SL1900/2000 is an inch smaller in width and depth and weighs 13.4 lbs vs 19.4 lbs for the SL 1700. That said, if it's in good condition it would probably be a good starter or second table.
Well there's a problem then, because the manual for the 1900 is over at vinylengine and the specs are not the same as what you state are listed in the brochure. It's very possible that Technics changed the specs before actually producing the turntable. I'd trust the specs in the manual that came with the tt before I'd trust a brochure.
You're comparing the the SL-1900/2000 with the SL-1700? Those are two different product lines--apples and oranges. The SL-1300 through 1800 MK1 and 2 were the upper level "pro" models, if you will. The 1900/2000 and successors were the lower level models. So certainly they are going to be smaller and lighter. You mention the D2; that's also a lower level model and was also smaller and lighter than the pro models.
Okay let's put this thing to rest, once and for all and compare apples with apples. This is directly from the manuals. Below is a comparison of the lower level, DD, full auto models, in chronological order. Yes, the specs went up--you'd expect that given the improvement in electronics each year. But as we know with other mfrs, that doesn't instantly condemn the older tables. According to the manuals, the tonearms are all 230mm with 15mm overhang. But as far as build goes, looks to me like they got lighter with each incarnation, not heavier:
SL-1900; .03 W&F; -73db; 15.9lbs
SL-3300; .03 W&F; -75db; 15.7lbs
SL-D3; .03 W&F; -75db; 15.4lbs
SL-D303; .025 W&F; -78db; 13.2lbs
And, of course, the testimonials of members like OneMalt and Mchaz about the 1900 tend to confirm the above and contradict the claims of cheapness.
Okay I found the brochure you're talking about at VE, and the 1900 is not in it. It lists the 2000, and then the higher models. So it is possible that the 2000 was a lightweight with lower specs, but if so, it was in that category by itself and shares none of that with the 1900.