Upgrading an HP 53131A into 53132A

[wholder]

I was looking over the schematics for the HP/Agilent 53131A and 53132A frequency counters and noticed that the component differences between these two models is very small.  I could have this wrong but both units seem to use use exactly the same front panel (same HP part number) and both seem to use the same PCB for the main board (but missing a few parts on the 53131A.)  Aside from a handful of passive parts, the main differences seem to be:

Additions for 53132A:
  U60 and U61 are both AD7580JP (10 bit A/D)
  U59 is a XC3042A-7PC84C (FPGA)
  U5 is a MC1403D_G

Changes from 53131A to 53132A
  U58 is changed from a XC3042A-7PC84C to a XC3142A-4PC84C
  U12 & U13 are changed from CY62256NLL-70SNXC to faster CY7C199CN-15VXC parts (256K bit SRAM)

There also the issue of the U14, which is a 64K-BIT EEPROM on both boards.  This might contain different code on the 53132A but, curiously, both are listed with the same HP part number, 1818-5128.

I realize this may be a fools errand, as most of these parts are very hard to very find, but I wonder if anyone has ever contemplated upgrading an 53131A into a 53132A?  The FPGAs are almost certainly the most challenging part, as I doubt one can readout the code from one that's programmed.  But, perhaps parts salvaged from a defunct 53132A might make this possible.  Update: It appears the FPGAs are confirmed by the onboard MC68331CEH16 processor, so that makes things easier.  Anyone else ever thought about, or tried this?

Wayne

Wayne

[TheSteve]

Should be possible. It has been discussed before here - in a repair thread I do believe. You will need the missing parts, new firmware and a calibration.