Checkout Procedure - Zenith H-100 Service Manual

5-168
PREWORK
Once you have received a H-207 Floppy Controller Board in
for service, use the checkout procedure below. Included
in the procedure are problems that may be identified before
power is applied to the circuit board. Many of the checks
below may have already been implemented in your preworking.
CHECKOUT PROCEDURE
Check the H-207 Controller Board for:
• Polarized capacitors installed backwards.
• 01, Q2, or 03 installed incorrectly.
• D1, D2, or D3 installed backwards.
• ICs installed backwards.'
• Dirty S-100 board contacts.
• Solder bridges.
• Cold solder joints.
• Resistor packs installed backwards.
• Correct jumpering.
• Switch settings of OS1.
• Correct voltage regulator for location:
7805 at PS1.
78M12 at PS2.
LM317 at PS3.
After making these checks, install the H-207 into your
H/Z-l00 test fixture and confirm the customer's complaint.
If the board appears to operate properly, align the
controller board using the procedure in the Alignment and
Adjustments section of this manual.
If the problem still exists, proceed to Service Hints.