Service manual

H/Z-100 Service Bulletins
In some of these revisions, the firmware will either initialize a circuit that wasn't
previously initialized or initialize it differently than before. The result is that the logic
states in these circuits may not match those shown in the Z-100 Interim Service
Manual.
In the Interim Service Manual, HE 860-15, volume one, there is a procedure
outlined on pages 2-112 and 2-113 describing power measurements of the power
supply with the supply unloaded. DISREGARD THIS PROCEDURE. When a switching
power supply is unloaded, the voltage measurements are unreliable. Therefore
perform any required voltage measurements with all modules connected, or use a
suitable power supply load.
FSB-Z100-019: ZW-120 Hard Drive Causes Floppy Disk Errors
Floppy disk errors in a Winchester environment may be caused by EMI radiating
from the hard drive to the floppy disk drive. To correct this problem, secure a shield
to the bottom of the Winchester drive. The shield was installed on later production
runs.
FSB-Z100-021: IC Change at U218
To permit the use of a multi-sourced part, the 96LS02 IC (HE 443-1040) at U218
was changed to a 9602 IC (HE 443-1112) on later production runs. This was not a
modification and the change was not required.
FSB-Z100-022: Dim Display
When troubleshooting a color video board, make sure that control R301 is in its fully
CCW position as viewed from the component side of the board. If this control has
been adjusted by the customer to a position other than CCW, a dim display may
result.
FSB-Z100-023: Changed Power Supply Part Numbers
The part numbers for the power supplies for the Low Profile Computer was changed
from HE-234-257 to HE 234-319 and for the All-In-One, from HE 234-256 to HE 234-
320.
FSB-Z100-024: Z-207 Floppy Disk Controller Card Soft Error Reduction
Connect a 10 uF capacitor in parallel with the 0.1 uF capacitor at C32. Be sure the
http://home.earthlink.net/~z100lifeline/data/Service.html (7 of 21)7/4/2004 1:41:55 PM