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GP49000 · 17th Nov 2012, 8:10 am

Zero Tracking Error and Belt Drive

The next step for the Zero 100 generation was belt drive, first applied to single-record players only.

The Zero 100SB - S for Single Play, B for Belt Drive - took the inverted thrust bearing of the AP76 and combined it with belt drive from the Synchro-Lab motor. A flat belt running on a motor pulley with crowned steps (to retain the belt in a central position on each step) was shifted between speeds by a plastic "fork" linked to the speed change control, which was combined with record-size selection for automatic single-record play. There was no speed adjustment. The Zero Tracking Error arm was almost the same as that on the Zero 100C, with magnetic antiskate and record-side counter; it only lacked the vertical tracking angle control, since a setting for multiple-record play was not necessary.

Automatic multiple-record play and user-adjustable speed were addressed in the next generation of the Zero Tracking Error models, the Z2000B. The platter bearing reverted to the ball-race type because the Z2000B had to accommodate a record-changing spindle using the proven mechanism from its predecessors such as the SL95B. Combining belt drive with user-adjustable speed proved more complicated. A tapered motor pulley drove an idler which moved up and down on the taper, as controlled by the user-accessible speed control knob. The idler carried a sheave, which drove a round rubber belt that in turn drove the platter.

The Z2000B record-changing system was the same as that in the SL95 series and the Zero 100: a center record-changing spindle and a side platform providing two-point record support.

I have found no evidence of a single-play version of the Z2000B; its logical name would have been "Z2000SB."

Those who read specification sheets and advertising on the large-chassis SL models, the Zero 100 idler-drives and the belt drives would have noticed that Garrard touted lightweight, 3-pound platters for the Synchro-Lab idler drive models, claiming that the synchronous motor reduced the need for flywheel action such as in the 6-pound platter of the Lab 80, and that the lighter platter put less stress on the ball-race platter bearing. But with belt drive the weight of the platters increased again, to five pounds. Garrard itself said this was necessary because while belt drive was quieter, further isolating motor vibrations from the platter, it also was a less direct coupling of the motor's driving force than idler drive, due to the elasticity of the belt. So mass had to be added back to the platter to maintain flutter as low as that from Garrard's idler wheel drives.

Zero 100SB photos:

Zero 100SB
Zero 100SB, platter removed
Zero 100SB, belt and speed change detail
Zero 100SB, underside
Zero 100SB, platter bearing

17th Nov 2012, 8:10 am	#64
GP49000 Hexode Join Date: Mar 2012 Location: Sonoma County, California, USA. Posts: 405	Re: Garrard record player deck identification. Zero Tracking Error and Belt Drive The next step for the Zero 100 generation was belt drive, first applied to single-record players only. The Zero 100SB - S for Single Play, B for Belt Drive - took the inverted thrust bearing of the AP76 and combined it with belt drive from the Synchro-Lab motor. A flat belt running on a motor pulley with crowned steps (to retain the belt in a central position on each step) was shifted between speeds by a plastic "fork" linked to the speed change control, which was combined with record-size selection for automatic single-record play. There was no speed adjustment. The Zero Tracking Error arm was almost the same as that on the Zero 100C, with magnetic antiskate and record-side counter; it only lacked the vertical tracking angle control, since a setting for multiple-record play was not necessary. Automatic multiple-record play and user-adjustable speed were addressed in the next generation of the Zero Tracking Error models, the Z2000B. The platter bearing reverted to the ball-race type because the Z2000B had to accommodate a record-changing spindle using the proven mechanism from its predecessors such as the SL95B. Combining belt drive with user-adjustable speed proved more complicated. A tapered motor pulley drove an idler which moved up and down on the taper, as controlled by the user-accessible speed control knob. The idler carried a sheave, which drove a round rubber belt that in turn drove the platter. The Z2000B record-changing system was the same as that in the SL95 series and the Zero 100: a center record-changing spindle and a side platform providing two-point record support. I have found no evidence of a single-play version of the Z2000B; its logical name would have been "Z2000SB." Those who read specification sheets and advertising on the large-chassis SL models, the Zero 100 idler-drives and the belt drives would have noticed that Garrard touted lightweight, 3-pound platters for the Synchro-Lab idler drive models, claiming that the synchronous motor reduced the need for flywheel action such as in the 6-pound platter of the Lab 80, and that the lighter platter put less stress on the ball-race platter bearing. But with belt drive the weight of the platters increased again, to five pounds. Garrard itself said this was necessary because while belt drive was quieter, further isolating motor vibrations from the platter, it also was a less direct coupling of the motor's driving force than idler drive, due to the elasticity of the belt. So mass had to be added back to the platter to maintain flutter as low as that from Garrard's idler wheel drives. Zero 100SB photos: Zero 100SB Zero 100SB, platter removed Zero 100SB, belt and speed change detail Zero 100SB, underside Zero 100SB, platter bearing Attached Thumbnails Last edited by GP49000; 17th Nov 2012 at 8:19 am.