[sebhc] H89 BOOT SUCCESS

Lee Hart leeahart at earthlink.net
Fri May 18 11:32:16 CDT 2007

Barry wrote:
>> The power supplies in all Zenith products prior to the Z-100 series
>> were linear power supplies, while the power supplies in all PCs are
>> switching power supplies.

Paul A. Pennington wrote:
> Not true:  the H/Z-89/90 had the mother of all switching power 
> supplies inches away from the disk drive in the form of a CRT assembly.  

No; Barry is correct. The H/Z-89/90s have linear power supplies. The 
deflection supply for the CRT is a switcher of sorts, but only supplies 
a small amount of power (8kv at less than 1 ma). The flyback transformer 
is also way on the opposite side of the case from the disk drive.

The problem is not from the flyback switching supply; it is from the 
radiated magnetic field from the deflection yoke on the neck of the CRT. 
It is relatively close to the disk drive, and by nature, disk drives are 
sensitive to magnetic fields. That's what the mu-metal shield was for 
between the disk drive and yoke.

Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in    --    Leonard Cohen
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net

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