2755p spec new to me


jeb_brygider
 

I traded for a 2755p and am having a problem starting it. While I have many years as an instrument tech, I am overwhelmed by this instrument. When started, it goes through it's startup, but shows a ROM sum error and that's about as far as it gets. Any and all suggestions are duly appreciated. Thanks in advance!
Jeb Brygider W2JEB Port Hadlock Washington


Harvey White
 

All the programming in the program ROMS is treated as data (numbers) and is added up.  That should come to a certain number (varies according to technique).  If that number is off, then either the data is bad, or reading of the data is bad, or both. There might be more information that shows which ROM is bad.

Generally speaking, though, with a bad checksum in the ROMS, the program should stop and go no further, since the instructions to the processor are suspect.

Somewhere in there, there ought to be words about ROM CHECKSUM ERROR or ROM CHECKSUM TEST which should (one hopes) allow you to narrow down the problem to a specific chip.

If you can't, and can't do a signature test on it (if available at all and you have the right equipment), then generally you'd take the ROMS out, program new ones, put them in, and hope it fixes the problem.

Some ROMS have a limited data retention time.  Some actually die over time.

Harvey

On 6/11/2021 11:53 PM, jeb_brygider via groups.io wrote:
I traded for a 2755p and am having a problem starting it. While I have many years as an instrument tech, I am overwhelmed by this instrument. When started, it goes through it's startup, but shows a ROM sum error and that's about as far as it gets. Any and all suggestions are duly appreciated. Thanks in advance!
Jeb Brygider W2JEB Port Hadlock Washington





John Miles
 

I traded for a 2755p and am having a problem starting it. While I have many
years as an instrument tech, I am overwhelmed by this instrument. When
started, it goes through it's startup, but shows a ROM sum error and that's
about as far as it gets. Any and all suggestions are duly appreciated. Thanks in
advance!
Not unheard-of, since these chips aren't getting any younger. If your firmware version coincides with one of those available at http://www.ko4bb.com/getsimple/index.php?id=manuals&dir=01_ROM_Images_and_Drivers/Tek_49x_firmware_and_notes you could replace the faulty EPROM by itself; otherwise you'll want to burn a whole set of the 9.7 firmware images (the last version released) and replace them all.

-- john, KE5FX