Calculator Maintenance; Environmental Limits; Determining If The Calculator Requires Service - HP -28S Manual

Calculator Maintenance
To clean the display, use a cloth slightly moistened with water. Avoid
getting the calculator wet.
Do not lubricate the hinge.
Environmental Limits
In order to maintain product reliability, you should observe the fol-
lowing temperature and humidity limits of the HP-28S:
• Operating temperature: 0° to 45°C (32° to 113°F).
• Storage temperature: - 20° to 65°C (- 4° to 149°F).
• Operating and storage humidity: 90% relative humidity at 40°C
(104°F) maximum.
Determining If the Calculator Requires
Service
Use these guidelines to determine whether the calculator is function-
ing properly. If the calculator does require service, see "Limited One-
Year Warranty" on page 291 and "If the Calculator Requires Service"
on page 293.
If nothing appears in the display when you press
I
ON
I:
1. Check the display contrast.
a.
Press and hold
I
ON
I.
b.
Press
GJ
several times.
c.
Release
I
ON
I.
d. If the display remains blank, press
ION
1
and repeat steps a,
b, and c.
A: Assistance, Batteries, and Service 289