Zenith H-100 Service Manual page 83

10-82
INTRODUCTION
To troubleshoot the H-207 Floppy Disk Controller, use this
section of the manual in conjunction with the schematic.
Located in this section of the manual are service hints
that will aid you in servicing the board. The schematic
contains voltages and logic levels of a normally functioning
board after a hard reset. By using standard troubleshooting
techniques, most problems can be quickly located and
corrected.
EQUIPMENT NEEDED
Frequency Counter
IM-2420 or equi val ent.
Logic Probe
IT-471 0 or equi val ent.
Low Capacitance Probe
PKW-105 or equi v al ent.
Multimeter
IM-2260 or equivalent.
Oscilloscope
IO-451 0 or equi val ent.
H/Z-IOO TEST FIXTURE
The H/Z-100 test fixture is set up so that the 5-1/4", 48
TPI disk drives are the primary boot device. Also, auto
boot is defeated (See "Configuration") .
It is assumed that the H-207 board is configured for
operation within the H/Z-100. That is, J1 is jumpered for
a 3 MHz or greater clock speed and DS 1 is configured for
port
80
(Hex), 48 TPI, and precompensation disabled.
5-167