Electronics > Repair

ANRITSU instrument boot up failed discuss(MS462X VNA)?

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mrf245:
Hi, I'm interesting in some old ANRITSU instruments system boot up failed (like MS462X series, I guess someone know that).
I got MS4623B from old factory, surely it can't boot up now. When power up, only fan is running but no display, no any light and any other response.
Tested all votage is OK, some people said check if BBRAM (M48T18) fault. BBRAM is SRAM with external battery and clock crystal, this BBRAM only 8KB but contain some system boot up information, if battery run out, data will lose result in boot up failed.
When system booting, before display show system information, BOOTLOADER chenking BBRAM data first, if error then will stop boot sequence.
I checked battery that is totally run out. BBRAM datasheet shows battery life is almost 10 years. no one know how long this 4623 stayed without running.
I guess that some other ANRITSU machines will use same method (bootloader+BBRAM or NVRAM), data in BBRAM was writing after whole machine assembled. New machine or repair, re-write data or file to BBRAM, it will running again.
Or make some setting access from ports (serial, JTAG,debug port,etc...), system will create proper data or file in BBRAM and running again (just like some TEK oscilloscope).
Anyone know how that work or any suggestion? Thanks very much. :) :) :)

precaud:
Do you have access to a manual? Many instruments have a "cold boot" or "reset" function which writes default values into the RAM before starting up, actuated by holding down some key while powering up.

imett:
i've the same problem, i could provide a memory dump of another instrument  but in my instrument doens't work.
nothing the instrument is halted. |O
Another way could buy from an ebayer a special patched flash that may work but he want 500$... :wtf:

mrf245:

--- Quote from: imett on May 02, 2018, 06:10:15 pm ---i've the same problem, i could provide a memory dump of another instrument  but in my instrument doens't work.
nothing the instrument is halted. |O
Another way could buy from an ebayer a special patched flash that may work but he want 500$... :wtf:

--- End quote ---

Hello imett, if you can sure your memory dump file is OK in new chips but your 4623 still doesn't work, check if any access signal feeding into M48T18 CE pin, ensure boot-loader running fine so program can check M48T18.
Ebayer a special patched flash I guess it bypass checking M48T18 process, but how to solve cal-data problem I don't know... :palm:

mrf245:

--- Quote from: precaud on April 28, 2018, 01:09:26 pm ---Do you have access to a manual? Many instruments have a "cold boot" or "reset" function which writes default values into the RAM before starting up, actuated by holding down some key while powering up.

--- End quote ---

Thanks, in service manual it only remind that "maybe U74 (M48T18) data lost" and "replace main processor board" but nothing detail about how to fix it.
I also guess it has special service menu when boot, should press some keys when power-up, or adjust switch in processor board, no manual mention it.

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