PCR1000 EEPROM corruption FAQ.

Now that the ICOM EX2099 software is 'wild', much of this FAQ is out of date. When I have time it will be updated. 

1. What are the symptoms?
 Users have reported some or all of the following faults.

• • AFC if selected in NBFM mode causes the radio to tune for ever downwards, signal present or not.
  • Bandscope shows decreased sensitivity.
  • Bandscope shows small signals present on all frequencies.
  • Radio is deaf over certain VHF/UHF frequency bands.
  • VHF & UHF sensitivity is badly affected MF and HF AM/SSB appears ok.

2. How many PCR1000s have been effected by EEPROM corruption?
Only ICOM can answer this question, but in the PCR user list at least 5 people have reported the fault.  This group has had a maximum of 150 members.

3. How do you fix it?
You can't, you have to send the radio back to ICOM.  ICOM can re-align the radio via their much talked of EX-2099 software.  I understand that the process requires RF test equipment and takes 3 hours.  This process puts a fresh set of calibration data into the EEPROM.

4. What is the EEPROM, what is it used for?
The EEPROM, or Electrically Erasable Programmable Read Only Memory, it is a form of memory that is supposed to remember data without being powered like a ROM, but also capable of being written to.  The PCR1000 uses a very small, standard I2C bus 128 byte EEPROM, a XICOR 24C01A.  Only ICOM know exactly what the data held in this EEPROM is used for, but generally such radios hold calibration data that is specific to the individual radio, data such as tracking filter look up tables and VCXO calibration values etc.  Often other items such as unit configuration, serial numbers or elapsed time recorders are also held in the EEPROM.

5. Where is the EEPROM?
The EEPROM in the PCR1000 is located on the logic PCB, directly underneath the mask programmed Hitachi Processor.  It is clearly seen in the picture below.

6. What causes EEPROM corruption?
The cause of the reported EEPROM corruption is not known.  Here is a list of possible causes.

• Accidental calling of the write commands via the RS232 command link.
• 
  It must be possible to write to the EEPROM, via commands on the serial port, as this is what the Icom calibration software must do.  At first I thought this was the most likely cause, that Icom had left the write commands inadequately protected.  However after over 240 hours of automated systematic searching and also random algorithms I have not been able to write to the EEPROM.  I believe I have found the write and read commands, but they do not work as I have not found the protection locks.
  Read Command LD0XX?                      Where XX= eeprom address
  Write command LD0XXYY                   and YY=data to write.
• **Note this is correct, the unlock code is GC01 followed by GCF0, but be very careful until you have a sound and verified backup!**

• Power drop outs.
• 
  If power to the processor is lost during a read or a write operation to the EEPROM, it is possible that the contents can be corrupted.  This is why many processors have a power monitor circuit to detect an imminent power down to enable read/write to be completed before the power is completely lost.

• Bug within the microprocessor firmware.
• 
  The could be a self  destruct  bug within the firmware of the masked programmed Hitachi processor.

• Processor crash due to overload of serial commands.
• 
  This would really be classed as a processor bug, that is triggered by overloading the processor with too many commands.  From my tests it does seem possible to confuse the radio, by sending commands too fast, and not waiting for responses.

7. What are ICOM doing about the problem?
Quote from Chris Ridley of Icom (UK), sent to me on 3rd June 1998:-

• "Whilst we do sympathise with your problems, ICOM (UK) Ltd cannot except responsibility for corruption of the PCR1000 calibration data by the use of third party software. Being the result of 'reverse engineering ' the data used to develop these programs may be inaccurate or incomplete. To the best of our knowledge no corruption of calibration data has ever occurred to any PCR1000 using the supplied software. Any problems you are experiencing are a result of shortcomings in the software you are using, not the PCR1000."
   

8. Is it safe to use 3rd party software?

• This is entirely your own decision.  Personally I think, as a result of my extensive tests, that as long as the programme has been carefully written to avoid overloading the radio with commands it is safe.

If you have any additional questions, comments, additions or criticisms on the above please Email me at "PCR@mahy.demon.co.uk".

For more details of the problem and other PCR1000 news, read or join the PCR-1000 mailing list at http://www.qth.net/ , from the select list choose PCR-1000.

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