9 Replies Latest reply on May 26, 2010 2:01 PM by daveinpoway

    How to resolve SG720 problem?

      I picked up this unit in a surplus store this morning, and the front-panel lights don't seem right- the light is on, the , , H/B and High Avail lights never come on. The for the 10/100 Ethernet ports (Ports C, D and E) flash every second; the LED's for the 10/100/1000 Ethernet ports (Ports A and B) do not light.


      I tried resetting the unit, and the lights still don't respond. I measured the power supply voltages, and +12V, -12V, +5V and +3.3V are all there, so the power supply is good. Pinging the unit at results in a message that the host is down, but, since I have no idea how the previous owner configured the unit, it might not respond to the ping even if it was working perfectly.


      Are there any inexpensive ways to get this working again? It is a nice firewall, and I would like to use it, but not if the cost to replace it is hundreds of dollars. McAfee told me that it did have a warranty until January, 2010, but there is no present warranty coverage.

        • 1. Re: How to resolve SG720 problem?

          the linux kernel is not running.


          you will need to recover the firmware, assuming that can be done, as a hardware issue coul;d also cause this problem.


          try using this utility




          http://go.mcafee.com/utm/downloads/snapgear/firmware/SG720-Recover_v1.0.6_200909 30.sgr



          the KB and user manaul refers to the operation of these files

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          • 2. Re: How to resolve SG720 problem?

            Well, I downloaded the Netflash routine and the recovery file, set the computer's Ethernet port to an IP address of, specified that I wanted the SG720 to be set to and ran the Recovery routine. "Listening for recovery request" came up as a green square, but the next step ("Booting SG unit") never was completed after 10 minutes of waiting. So, either the SG720 is defective or I was not running the recovery routine correctly (I have never used this before, so I have no experience with how it is supposed to work).


            I have noted that the two IC's under the heatsink never get even slightly warm, but, never having used an SG720 before, I don't know if they will stay cold merely because of firmware corruption or if this indicates something more serious. The (non-removable) heatsink prevents access to these IC's in order to make any measurements on their pins.


            I also see that inductor L7 has no DC voltage on either side of it, but I have no idea where this is connected in the circuit (since I have no schematic). The logic board has an edge connector (probably to plug into some test fixture at the factory), but I have no idea what voltages and waveforms are supposed to be present at any pins of this connector, so probing there won't help me.

            • 3. Re: How to resolve SG720 problem?

              connect a RS232 null modem cable to the serial port, 115200 8n1


              when rebooted you may get output on the serial port.


              If not, when powering up the device, hold the 'erase' button.


              Do you see serial output ?


              If not, it is dead

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              • 4. Re: How to resolve SG720 problem?

                Does the firmware which causes data to be sent from the Serial port when the unit is powered-up reside on the Compact Flash card, or is there a separate boot ROM on the circuit board?


                Update- when I turn the unit in, nothing appears on the computer screen from the firewall's Serial port. However, I tried my SG560 (which I know is working perfectly)- nothing is displayed from its Serial port when I turn it on, either. So, this may well not be an accurate diagnostic regarding the SG720's condition.



                Message was edited by: daveinpoway on 5/22/10 3:53:42 PM CDT
                • 5. Re: How to resolve SG720 problem?

                  you need to hold the erase button while powering up to get output on the serial port.


                  All stored on the flash card.

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                  • 6. Re: How to resolve SG720 problem?

                    Thank you. I held in the Erase switch and applied power. I kept the switch pushed in for 10 seconds- nothing was displayed during that time. I then released the switch- nothing was displayed. With no schematics, not too likely that I can locate the hardware failure(s) on my own. So, project over (for now).


                    If the data on the CF card was missing or corrupted, would I still get something displayed from the Serial port? I can see that there are 2 partitions on the card, but I cannot read out the data, so I don't know if both partitions contain the proper information. There is a routine that can update the bootloader, but it appears that this has to run on an operating unit. I haven't seen anything that will rewrite the bootloader if the appliance won't start up. At the factory, they probably used the edge connector on the board, plugged into a special test fixture.   


                    If I had a second (working) unit, I could try swapping the CF card. Perhaps I will eventually find another SG720 with a good logic board and a bad power supply. I could then use that board and my good power supply to make a working unit.


                    Edit- I tried the SG560- while the button was being held in, I received a message related to a recovery bootloader. So, my setup is capable of displaying the information (if the SG720 was sending out anything).



                    Message was edited by: daveinpoway on 5/24/10 7:26:51 AM CDT
                    • 7. Re: How to resolve SG720 problem?

                      Yes, the first partition is boot, which need to be loaded via a working unit, special connector, or replacement.

                      • 8. Re: How to resolve SG720 problem?

                        Thanks. I was afraid of that.

                        • 9. Re: How to resolve SG720 problem?

                          The little heart is now beating (although slower than it should)! It turned out that a 33 MHz crystal appears to be defective. I have a 14 MHz crystal (from an old PC motherboard) installed for now- the front-panel lights do the right things. So, it appears that the CF card is not corrupt, and this unit can be saved from the scrap pile.


                          Now I need to track down another crystal (of the proper frequency). Hopefully I can get a vendor to send me an engineering sample, since ordering one crystal is something most companies don't want to deal with.