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ZyXEL modem FAQ List v4.2, Nov 20 1995, Part 3 of 5 [Technical FAQs]
Section - T.27A What exactly is the hardware modification needed for CID/CND and EDR?

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Top Document: ZyXEL modem FAQ List v4.2, Nov 20 1995, Part 3 of 5 [Technical FAQs]
Previous Document: T.27 How does one make Caller ID (CID/CND) work correctly?
Next Document: T.27B What software modifications are needed?
See reader questions & answers on this topic! - Help others by sharing your knowledge
--------------------------------------------------------------------------------

Brent Mosbrook (brentm@zyxel.com) [ZyXEL USA] writes:
"All new ZyXEL modems have a hardware modification performed at the factory.
A capacitor has been added to filter the Caller ID data.

Current owners can have their modems upgraded by sending the modem back to 
ZyXEL, and we will install this capacitor for them.  This might not be 
necessary, and is only recommended for people who live in an area with CND, 
and cannot get it to work.  

Any ZyXEL owner can call us and we will help them determine if they have the 
capacitor installed."


Brent Mosbrook (brentm@zyxel.com) [ZyXEL USA] writes:
EDR on non-US modems:

It has come to our attention that EDR (included with 6.11a roms) does not work 
on modems bought outside the US or Canada.  North American modems have a 
capacitor installed which is used to filter CID, and other tones received
prior to the modem going off-hook.  ZyXEL will not be referencing EDR 
capability on any "international" modems sold.  

Customers who wish to install this capacitor may do so at their own risk
(local telco regulations may restrict performing this modification).  
Due to these possible restrictions, ZyXEL will not be offering a factory 
upgrade, but will help customers in identifying 1) whether or not they 
currently have the capacitor installed. 2) where the capacitor should be 
located.
  

NOTE:   DOING THIS MODIFICATION WILL VOID YOUR WARRANTY, AND MAY VOID THE
        LOCAL PTT APPROVAL.


A .033 uF capacitor needs to be installed parallel to resistor R4
(100K ohms), which is located in different places according to the model, 
and revision level of your modem. A diagram showing the lastest revision 
levels is included to show the general area where R4 can be found.  R4 is 
generally located near the relays (large yellow, brown or black boxes).  
The color code for R4 is brown-black-yellow-gold.(some locally approved 
models may have other values. Generally it is between 75K and 150K ohms.) 
The capacitor should be non-electrolytic, and rated at 100V or higher.  


(these are the latest rev. levels.. older models may differ significantly)

1496S/S+ modems:
----------------

                              RJ-11      RJ-45
---------------               ---  ---  -----
|    RS-232   |               | |  | |  |   |
---------------               ---  ---  -----


                 -------
                 |RELAY|
                 -------
                 -------  o
                 |RELAY|  !  <-- R4
                 -------  o
                 -------
                 |RELAY|
                 -------


1496E/E+ modems:
----------------

                              RJ-11      
---------------               ---  ---  
|    RS-232   |               | |  | |  
---------------               ---  ---  


                           -------
                           |RELAY|  o
                           -------  !
                           -------  o
                           |RELAY|  o
                           -------  !  <-- R4
                                    o 
                         

1496B/B+ modems:
----------------


                                           |-
         ----------------------------------|
                                           |
                                         --|
                                         | | RJ-11
                                         --|
                                         --|
                                      o  | | RJ-11
                               R4 --> !  --|
                                      o    |
                                           |
                                           |
                                           |
        -----------------------------------|
                                           |


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Top Document: ZyXEL modem FAQ List v4.2, Nov 20 1995, Part 3 of 5 [Technical FAQs]
Previous Document: T.27 How does one make Caller ID (CID/CND) work correctly?
Next Document: T.27B What software modifications are needed?

Part1 - Part2 - Part3 - Part4 - Part5 - Single Page

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