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- PART XII. HOW THE ESN IS REPLACED
-
- It takes some electronics skill to pull or unsolder the ESN. If you
- are sketchy about messing around with your phone, I suggest practicing on
- something else first, like an old calculator or something. It is also a
- good idea to use the proper tools (A very small soldering tip,chip pullers,
- It is imperative NOT to touch any of the surrounding connections, soldering
- joints, or chips. The job MUST be done right the very first time. After
- that it is not so important, because after the first time you should have the
- ESN information stored safely to disk. The only dangers remaining are
- physically damaging the chip. (Note: There are devices that wipe PROMs
- clean in the event of programming errors).
-
- When removing the ESN, try to follow these 5 steps:
-
- A. Remove the PC board containing the ESN from the entire phone unit. The
- boards are usually screwed in with Phillips heads. This will insure
- against damage to the rest of the unit.
-
- B. Ascertain the correct chip. Find the letters on the chip, and check it
- against the letters from the IDENTIFYING THE ESN section. Refer to the .Gif
- file included if necessary.
-
- C. It is a good idea to draw a sketch to help you remember which way the chip
- went in. You may laugh, but do it anyway.
-
- D. Carefully remove the chip. Take your time and use the proper tools.
-
- E. Solder in a zero insertion force (ZIF) replacement, so that replacement
- chip can be changed easily.
-
- After the ZIF socket has been successfully soldered in, reinsert the
- ESN and attempt to make a phone call (Be sure the NAM is programmed
- correctly). If it doesn't, check the leads on the ZIF to insure that you
- have soldered them correctly. After that, insert your ESN into your PROM
- reader and make sure it provides some sort of reading. You should use the
- search mode to look for the manufacturers serial number.
- (see MANUFACTURER'S ESN CODE LISTING) to identify the address on the PROM
- where to reprogram the ESN.
-
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