Electronics > Repair

Fluke 5500a repair attempt

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ddrl46:
Srikanth:

Try connecting a null-modem type RS232 cable (or USB -> RS232 adapter) to the SERIAL 1 port (the male one).
Open a terminal program (i use termite rs232), configure it for 9600 baud, 8 data bits, 1 stop bit, no parity, no flow control, linefeed enabled.
Press and hold the reset key on the calibrator front panel and power it up, check to see if the calibrator displays "RESET KEY HELD" on the right hand display.

From the terminal window see if you get a message indicating that the RESET key has been held and press return to enter the command line, send a "?" to the calibrator to get a menu listing of all options.
You can check to see if the firmware is deemed to be corrupted by the calibrator by running the "checksum" command which is displayed in this list.

If your firmware is indeed corrupted, reprogramming should be possible via the RS232 interface using the "serial outguard download" command. I've not yet figured out how this command is supposed to work.

dcmxx:

I've ordered the revised A9 CPU boards and they should be here in a few weeks. When I've completed testing them I'll contact you.

dcmxx:
I programmed the memory chips with a cheap TL866II programmer, but obviously you have to remove them from the board and put them in an adapter and then in the programmer.

ddrl46 has already posted the firmware dump so if that's the cause, you should be able to bring it back to life

Srikanth:
Hi ddrl46,

              Thanks, firmware is corrupted on serial port "Flash Checksum fail". firmware can be upload via serial or do we need to use Jtag, please advice.

Thanks. 

Srikanth:
Thanks, I got firmware, please help on how to download.

ddrl46:

--- Quote from: Srikanth on June 13, 2023, 07:59:50 am ---Thanks, I got firmware, please help on how to download.

--- End quote ---

Like dcmxx mentioned, your best bet is to de-solder the three flash chips from the A9 cpu board and flash them using an EEPROM programmer. A TL866II with the proper ZIF sockets should do the trick.
Keep in mind that all calibration data in your unit will be lost, and that full re-adjustment will be required after flashing.

If someone feels up to the challenge it would be possible to update the flash memory via the serial port with the "SRECV" or "GRECV" commands in the bootloader menu.
Unfortunately I was unable to figure out how these commands work, them seem to throw back an "Aborted" message regardless of what I do. Figuring this out would likely require disassembly of the bootloader.

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