CHAPTER 1 INTRODUCTION
1.3 TOOLS AND TEST EQUIPMENT REQUIRED
1. Common hand tools
2. Standard electronics tool kit
3. Digital Voltmeter (DVM) capable of reading from 1 mv to 50 V dc.)
4. Megohmeter (50 Volt dc maximum test voltage)
5. Desk magnifier on a stand
6. Ohaus Indicator: Defender 3000, 5000, 7000, or equivalent commercial indicator
7. A calibrated Torque Wrench N.m. – Ft/Lbs
1.4 TEST MASSES REQUIRED
The masses required to test the Ohaus Defender H-Q-W Series Bases when connected to an
Indicator must meet the requirements of ASTM Class 4 or OIML F2. Mass values 3kg to 300kg,
depending on the Base model. The full scale rated capacity of the Base should be used for
Span calibration.
1.5 SERVICE
STRATEGY
The Load Cells used in Ohaus Bases are non-repairable. The repair method for the Base is
direct replacement of Load Cells with connecting cable and hardware.
Each base contains the following basic replaceable assemblies: Platform, Load Cell with
Connecting Cable, and Down Stop and mounting hardware. There is an exploded view drawing
of the Base and associated parts list in Chapter 5. This service manual contains sufficient
information to isolate the problem, replace the component, test and restore the Base to
specifications.
1.6 PHYSICAL DESCRIPTION: DEFENDER BASES
Construction
H and Q Series
(General Purpose Bases):
Platform – Stainless steel
Frame – Painted Carbon Steel
Load Cell – IP 67 Aluminum
W series
(Washdown Bases):
Platform – Fabricated stainless steel
Scale Base – Formed and welded stainless steel
Load Cell – IP 67 Stainless steel
Overloading
Corner Loading – 100% of Full Capacity
Safe Overload – 150% of Full Capacity
Ultimate Overload – 300% of Full Capacity
Operating Environment Designed to meet OIML 3000e and NTEP 5000d requirements
to operate at a temperature range from –10°C to 40°C /
14°F to 104°F, 0 to 95% relative humidity
Ohaus Corporation www.ohaus.com
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Defender™ H-Q-W Series Service Manual
Summary of Contents for Defender D15HR
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