Motorola T720PA Service Manual
Consumer Solutions & Support US Competency Center
600 North US Highway 45 Libertyville, Illinois 60048
Website: gs.mot.com
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FIELD SERVICE BULLETIN |
FSB Number: |
LVCCFSB2004-101 |
Author: |
Hien Huynh |
Date: |
April 30th, 2004 |
Total No. of Pages: |
3 |
Subject: |
GSM T72x – PA Rework. |
Model Affected: |
T720, T720i, T721, T722. |
Level of Repair: |
3 |
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Problem
Field service in Asia & EMEA has highlighted a “No Power-up, No TX or Short Battery Life” issue. In the analysis of PA it was found that the (Source to Vcc), PA_B+ pin 6, 11, and / or 16 are shorted to ground. Symptoms show an excessive current draw of 500mA to 1.5 Amps at power up. Also, MFAL and supplier analysis show the GCAPIIIE93, PGND was burned. Supplier analysis result show if input voltage is more than 13V, pulse with more than 1ms, it can damage the IC.
Solution
Design change has proposed to replace C7001 from 10uF(2113928C12) with a 6.8V Zener Diode ( 2113928Z11) and increase C7000 from 10uF(2113928C12) to 22uF capacitor (4809788E17). Zener Diode is to prevent over voltage pulse surge from protection circuit. 22uF capacitor will act as original 2 x 10uF capacitors to stable the B+ voltage.
Field Service Action
Customer Returns:
When servicing GSM T72x customer returns, it is suggested that the part changes be implemented as shown in picture below:
(1)Check the PAU400 (5109908K66) and U3000 (5109879E83) GCAPIII to make sure that they are in normal operation.
(2)Replace C7001 with 10uF(2113928C12) to a 6.8V Zener Diode (2113928Z11)
(3)Replace C7000 with 10uF(2113928C12) to a 22uFcapacitor(4809788E17).
(4)Reassemble the PA shield, then the unit
(5)Re-phase.
MOTOROLA INTERNAL USE ONLY |
Page 1 |
Consumer Solutions & Support US Competency Center
600 North US Highway 45 Libertyville, Illinois 60048
Website: gs.mot.com
(2)Change C7000 from 2113828C12 (10uF) to 4809788E17(22uF Capacitor)
(1) Remove the PA shield |
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(3) Change C7001 from 2113828C12 (10uF) |
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to to 2113928Z11(6.8V Zener diode) |
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Service Inventory:
N/A
Service Entry Codes
Please ensure that repairs of this type are logged in the service database as follows:
Asia Codes:
Fault Code: 03 Short Battery Life
04 Can’t Power up / Power Failure
MOTOROLA INTERNAL USE ONLY |
Page 2 |
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