SERVICE AND REPAIR NOTES
Bulletin
TECHNICAL INFORMATION / 8000 W. SUNRISE BLVD. / FT. LAUDERDALE, FL 33322

SRN-1313

APC �422, 672, 749

Date: July, 2000

Deadline: April 30, 2001

Memo To: SRN Mailing List

From: Radio Products Division /Plantation, FL

Subject: Static Noise or High Pitched Whine on HT750/HT1250 and CT250/CT450 Series Radios

Symptoms:

The user may hear a static sound or a high pitched whining sound on the radio speaker in the stand by mode

regardless of the volume control setting. The whine is also present when using a remote accessory such as a

microphone.

Potential Problem Radios:

Models Affected: AAH25BEC9AA3AN, AAH25CEC9AA3AN, AAH25KDC9AA2AN, AAH25KDC9AA3AN,

AAH25KDG9AA4AN, AAH25RDC9AA2AN, AAH25RDC9AA3AN, AAH25RDG9AA4AN, AAH25SDC9AA2AN,

AAH25SDC9AA3AN, AAH25SDG9AA4AN, AAH25BEF9AA5AN, AAH25CEF9AA5AN, AAH25KDF9AA5AN,

AAH25KDH9AA6AN, AAH25RDF9AA5AN, AAH25RDH9AA6AN, AAH25SDF9AA5AN, AAH25SDH9AA6AN,

AAH25RDH9DU5AN, AAH25RDH9DU6AN, AAH25SDH9DU5AN, AAH25SDH9DU6AN, AAH34SDF9DU5AN,

AAH34SDH9DU6AN, AAH34KDC9AA1AN, AAH34KDC9AA2AN, AAH34RDC9AA1AN, AAH34RDC9AA2AN,

AAH34SDC9AA1AN, AAH34SDC9AA2AN, AAH34KDH9AA6AN, AAH34RDH9AA6AN, AAH34SDH9AA6AN

Serial Numbers: 422TAGxxxx through 422TAPxxxx

672TAGxxxx through 672TAPxxxx

749TAGxxxx through 749TAPxxxx

Cause:

The whine is caused by a defective lot of audio power amplifiers that were manufactured with slightly different specifications

requiring a different biasing resistor.

Corrective Action:

Change resistor R471 from a 5.6K ohm to a 20K ohm, part number 0662057N06. Radios must be sent to one of the two Centers

referenced below for repair.

Motorola Inc. Motorola Federal Technical Center

3761 South Central Avenue 4395 Nicole Drive

Rockford, IL 61102-6772 Lanham, MD 20706-4349

800-227-6772 or 815-489-1000 (800) 969-6680 or (301) 731-6676

Note: The Motorola U.S. Federal Government Depot is primarily used for all Federal Government Customer

Accounts.

When returning the portable please reference this SRN.