Electronics > Repair
Tektronix TDS754C digDataFormatDiag error and option 2M
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hackwell:
Hi,
this post is to share some intersting things I found while repairing my TDS754C ACQ board.
It was showing digDataFormatDiag errors which means there was some defective SRAM in the ACQ memory.
The error from the console port looks like this :
ERRORID: 162 diagnostic test failure digDataFormatDiag1MMem
ERROR!!in demux 199 ,i= 6 memBaseAdr 0x734000e= data = 300, expectedData = 5500
the DMUX numbering and addresses are :
demux 198 : U400 base address 7300000 memory chips U401 to U416
demux 199 : U300 base address 7340000 memory chips U301 to U316
demux 200 : U200 base address 7380000 memory chips U201 to U216
demux 201 : U100 base address 73C0000 memory chips U101 to U116
The i = x (where x = 0 to 15 in decimal) is very interesting. It tells you which chip is bad by adding 1 to it.
ex : i = 6 points to U307 chip in the line above
or you can as well divide by 2 the least significant byte of the given memBaseAdr
ex 0x0e / 2 = 7 -> U307
The test routine writes 2 bytes to each memory chip the reads back the result. The expectedData word changes for each tested chip.
I've noticed 0x0 , 0x08001 , 0xFF00 , 0x0a00 , 0x5500 and 0xFF00. Not very useful though.
Another very intersting thing I found is the digDataFormatDiag error itself
it comes in to flavors : digDataFormatDiag1MMem and digDataFormatDiag2MMem depending on the size of the total ACQ memory.
My board has 512 Ko but some board have 1 Mo or 2Mo depending on the version and revision I guess.
This is about options 1M and 2M.
the size of the ACQ memory is detected by the power up routine at the beginning:
Limit to 1GS/sec presence
Opt Math Package presence
Opt Telecom Masks presence
Opt 3C presence
Opt 4C presence
Opt RS232/ Cent presence
Opt 1M presence
Opt 2M presence
Acq Intlv Cal Id presence
Opt TvTrig presence
Opt TvTrig index
and set automatically regardless of the NVSRAM contents. So if you enable option 2M via GPIB and if your board has only 512Mo it'll be ignored.
I noticed this when I replaced the memories in channel 1 . The 2M option appeared in the banner and I got an error in channel 2 which I knew was working so far.
I don't know how this happened exactly but it was caused by a bad brand new chip in channel 1.
Hope this helps
alessandrocorv:
Hi hackwell, your post is extremely helpful but I have the following error:
digDataFormatDiag, ERROR!!BYTE mode, in demux 199 ,i= 22 memBaseAdr 0x734002e= data = 7c00, expectedData = 7800"
but no there is a U323 chip in the memories.
how can I figure out who is causing the error?
Thank you
Alessandro
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