NEC nd-20292 manual 2of8

Cabling

Grounding

Outside lines

Some RF1 conditions cannot be addressed in this bulletin due to the many possible variables involved. These variables are generally particular to each site and require that pertinent data be known, such as the frequencies involved. In situations where RF1 is still present after following the instructions provided in this bulletin, contact your local NEC America, Inc. SBS Field Support Engineer for further assistance in resolving the RF1 condition.

If RF1 is present during CO (outside) calls, check for RF1 at the Telephone Company on site demarcation terminal, with the Electra Mark11 system isolated from the demarcation terminal. If RF1 is present at the demarcation terminal, contact the local Telephone Operating.Company.

If RF1 is not present at the demarcation terminal, reconnect the Electra Mark11 system and go off-hook at a Multiline Terminal with RF1 present in the handset and stretch the handset cord. If RF1 changes (increases or decreases in amplitude) when the handset cord is stretched, modify the Multiline Terminal as outlined in step 4. If RF1 does not change, contact your local NEC America, Inc., SBS Field Support Engineer.

4.PROCEDURE - RF1 LOCALIZED TO THE HANDSET

4.1Disconnect the modular cord from the handset.

4.2Open the handset (See Figure 1).

4.2.1Remove two screws from the inside grip of the handset.

4.2.2Set the handset face down (transmitter and receiver facing down) over a solid, clean surface. Place the fingers of one hand under the transmitter end and with the thumb of the same hand apply downward pressure to the center of the handset grip. With the other hand, at the receiver end, separate the handset halves.

4.3Inside the handset half containing the receiver and transmitter elements, loosen the screws holding the leads to the receiver and transmitter elements. Obtain two .OlpF ceramic disk capacitors and cut both capacitor leads approximately 3 inch in length as shown in Figure 1. Install one .OlpF ceramic disk capacitor across the receiver element and another .OlpF ceramic disk capacitor across the transmitter element. Use plastic sleevingover.the capacitor leads to prevent electrical shorts. Tighten the screws and secure all leads. (See Figure 1).

-4.4 Join both halves of the handset and secure with two screws (Removed in 4.2.1).

4.5Connect the modular handset cord and test the station for RF1 and normal audio levels. If RF1 is still present, continue to step 4.6.

4.6Open the handset (Refer to 4.2).

4.7Solder a length of insulated, single strand wire to each lead of a .Ol ~,IFceramic disk capacitor. Ensure the wire is the same gauge as the capacitor leads and long enough for one capacitor lead to reach one of the transmitter element screws and the other capacitor lead to reach one of the receiver element screws inside the handset (See Figure 1). Use shrink sleeving over the prepared capacitor leads to prevent electrical shorts. Inside the handset half containing the receiver and transmitter elements, loosen one screw from each element (transmitter and receiver) and install the .Ol pF ceramic disk capaci.tor between the transmitter and receiver elements.

4.6Join both halves of the handset and secure with two screws (Removed in 4.2.1)

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