Complete manual with clear schematic diagrams and printed circuit board layouts of two variants of the headset and the transmitter an old and a new version.
Also shows how the headset and the transmitter is opened and how transmitter and receivers can be adjusted and where to measure.
I had no problems to repair the headset using this service manual.
This is a great site. I placed my order and by the next am it was available for download. Had some problems with some missing copy on some pages. Once I brought the error to the OMC's attention, the issue was resolved. I'll come back again.
The quality of this manual is good. It has all schematics and setup information for both the MDS-B3 and the MDS-B4. The scan quality is quite good, all pages are readable, This service manual also contains scans of the operating instructions from the User manual.
Text excerpt from page 56 (click to view)
GX15
3. No voice is heard from the earpiece.
Phone (Handset) Do keypad tones and melodies sound?
YES
CONFIDENTIAL
NO
Go to the section �Earpiece (for loud speaker) does not work�. (see page 2-50)
Is 0.5 V or more applied to R101 (IC103 pin 9 side)?
NO
YES
IC103 is defective.
Is 0.5 V or more applied to JK101 pin 5?
NO
YES
Parts between socket JK101 pin 5 and IC103 pin 9 are defective.
Is 0.5 V or more applied to JK101 pin 3?
NO
YES
Socket JK101 is defective.
Is 0.5 V or more applied to TP120?
NO
YES
Parts between socket JK101 pin 3 and TP120 are defective.
Is 2.4 - 2.6 V applied to TP176?
NO
YES
R122 is defective.
Is 2.4 - 2.6 V applied to R115 (IC103 pin 76 side)?
NO
YES
R115 is defective. (Hands free kit mode is set.)
IC103 is defective. Hands free kit (Headset) Replace the hands free kit. Is sound produced?
NO
YES
The hands free kit is defective.
Is signal sent to JK101 pin 4?
NO
YES
Socket JK101 is defective, or the hands free kit is in a poor contact with the socket plug.
Is signal sent to TP121?
NO
YES
Parts between socket JK101 pin 4 and TP121 are defective.
Is signal sent to R124 (IC103 pin 60 side)?
NO
YES
Parts between IC103 pin 60 and TP120 are defective.
Disconnect the hands free kit. Is voice heard in phone mode?
YES
