Electronics > Repair

Fluke 5500a repair attempt

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Some months ago i received an almost complete Fluke 5500a MFC that is missing the A9 Main CPU Board. It even haves the SC300 option.
Since then i have waited to come across with one of that boards without luck

Instead i have come across a A9 board from a 5820 osciloscope calibrator wich is the exact same A9 board for the Fluke 5520a MFC but with different firmware.

Altough the board is not exactly the same as the A9 of the 5500a i'm almost sure that if I program the firmware of the 5500a's board in the 5520a's board it will work

One of the main differences are that the uses bigger flash memories and instead of one for the lower word and one for the upper word in ROM Bank 0, the 5520a's  board uses a single bigger flash memory.

I removed all the other function boards form the calibrator and connected the 5520a/5820a A9 board to the main backplane board, and turned on the instrument. It energizes both displays and tries to start up. But without the boards it stay stuck there as expected.

The problem I have right now is that I have no source for the firmware dump of the flash memories, so if anyone has it or is able to dump it, it will be greatly appretiated. If there's some cost assosiated, as long as it is rasonable, i don't have any problem in paying it. The needed dump is from the U1, U26 and U27 memory chips of the A9 board for the Fluke 5500a MFC

I attach pictures of the 5820a/5520a board

Are you sure that the A9 card is the reason why the device does not turn on and all the lights are on?

The 5500a is missing the A9, so if i turn it on, it doesn't do anything. So i'm pretty sure the problem is the missing A9 board. thats why i'm trying to replace it with the a9 board from a 5820a/5520a

Besides the firmware being different between the 5500A and 5520A A9 boards there is also a difference in the pinout of the cable which goes to the A3 motherboard.
You might want to compare the schematics of the Fluke 5500A with the CPU board listed in the Fluke 57LFC service manual (which is the same one used in newer Fluke 5520A units).

I'm actually currently working on putting together are 5500A unit from parts which I've gathered, and for this project I've had to recreate a few of boards. One of these being the A9 board.
There are currently still a few issues I'm ironing out, but I may have some boards left over when I'm done. I also have access to the firmware, but I'll have to do do some work on that before I can share it.

that's a really nice proyect, if you consider selling the boards i'm definetly interested in one, even if I make the 5520a's board work, due to the fact the A9 board from the 5520a is not the same size as the original A9 of the 5500a.

I also thought about the posibility of recreating the board from the available schematics, but i haven't had much free time lately so that's not an option right now.

hope you could share the firmware dump when it's possible. and thanks for the hint about the pinout, i will check it out


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