EFJohnson 7780 Material Classification, Typical Hazard Group Class, Area Classification

GENERAL INFORMATION

Table 1-2 Material Classification

Typical Hazard		Group	Class
Acetylene		A	I
Hydrogen		B	I
Ethylene, ethyl ether, cyclopropane		C	I
Gasoline, naphtha, butane, propane,		D	I
alcohol, acetone, benzol, natural gas
Metal dust including aluminum, mag-		E	II
nesium, and their alloys
Carbon black, coal, or coke dust		F	II
Flour, starch, or grain dusts		G	II
Ignitable fibers/flyings such as rayon		-	III
or cotton
Table 1-3 Area Classification
Division	Area

1An area where there is or could be an explosive atmosphere most of the time in normal opera- tion

2An area where an explosive atmosphere exists only as a result of a fault (something going wrong)

1.11ACCESSING PC BOARDS

1.11.1 INTRODUCTION

The RF unit is located under the back cover and the logic unit is located under the front cover. These boards connect together using a 30-pin connector on the bottom side. Since both boards have numerous parts on the bottom (hidden) side, the board may need to be removed to replace components. To operate the transceiver with the RF unit removed, a special exten- sion test cable is required.

Also inside the transceiver are display and keypad boards. These boards are mounted to the inside of the front cover. Proceed as follows to remove the RF and logic unit board from the transceiver.

1.11.2 REMOVING TRANSCEIVER CASE

To access the internal parts in the transceiver, the plastic case must first be removed. Proceed as follows:

1.If you have not already done so, remove the battery by pressing the release button upward and then sliding it off the transceiver. If the belt clip is mounted on the back, it must also be removed.

2.Remove the three screws in the back and two in the bottom end that are indicated in Figure 1-1. Slide the case off.

3.Removing the two screws in the end also allows the front panel to be removed. Simply lift it outward if desired. If you do not want to remove the front panel, temporarily replace one of the end screws.

CAUTION

Excessive flexing of the ribbon cables may result in broken traces.

REMOVE

THESE

SCREWS

Figure 1-1 Removing Case Screws

1.11.3 UNPLUGGING FLEX CABLES

The flex cable to the front panel and also the accessory jack and PTT switch flex cables to the logic board are inserted into a locking-type connector. To release the cable so that it can be removed from the connector, the locking tangs must be pulled out as shown in the following illustration.

November 1999
Part No. 001-7780-500	1-6