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TDS744A Error message digDataFormatDiag

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phaiduc
Posts: 6
Joined: April 25th, 2018, 12:10 pm
Country: Romania

TDS744A Error message digDataFormatDiag

Post by phaiduc » April 25th, 2018, 12:52 pm

Hello

I've just got an old TDS744A that fails the Acquisition test with the following message in the error log:
"Tue 04-24-;8 21:35:56 ERROR: diagnostic test failure,
digDataFormatDiag,
ERROR!!in demux 200 ,i= 21 memBaseAdr 0x738002c= data = 200, expectedData = 1200"

I suspect one of the SRAM chips connected to demux U200 has a bit stuck in 0.
This is confirmed by the fact that I see random spikes in the signal displayed for channel 4.
Luckily channels 1, 2 and 3 work fine.
The problem is how can I identify the chip.
There are 16 8kbyte SRAM chips connected to U200

Many thanks for any hints.

fenugrec
Posts: 77
Joined: January 18th, 2017, 3:51 pm
Country: Canada

Re: TDS744A Error message digDataFormatDiag

Post by fenugrec » April 27th, 2018, 7:57 am

phaiduc wrote:
April 25th, 2018, 12:52 pm
I've just got an old TDS744A
me too - what fw version is yours ?

Code: Select all

ERROR!!in demux 200 ,i= 21 memBaseAdr 0x738002c=  data = 200, expectedData[i] = 1200
There might be a service function to loop test a specific address, but I'm not sure. I'll try to check next time I'm looking at the firwmare.

The TDS520 has a 64-bit wide data bus for the acq RAM, I believe the 744A is also 64-bit wide. If they kept the same organisation on both models, I would assume a memory map like this :
Ux01 : address + 0
Ux02 : address + 1
...
Ux08 : address + 7

As the TDS520 manual says, "the defective IC is Ux0n where n = (address modulo 8) + 1. This would be Ux05 on yours.
Since you have 16 ICs (and not 8 like the TDS520), I would imagine there are 8 for the lower bank (maybe 0x738 0000 to 0x738 FFFF) and 8 others for the upper bank at 0x7390000... This is assuming channel 4 memory starts at 0x738 0000. I can't confirm this; I thought the entire sample memory started at 0x730 0000...

This is all guesswork on my part, I could be 100% wrong!

strick
Posts: 110
Joined: March 22nd, 2016, 11:23 am
Country: United States

Re: TDS744A Error message digDataFormatDiag

Post by strick » April 27th, 2018, 3:06 pm

Phaiduc,
I believe fenugrec is real close to correct.

There are two things that need to be looked at before you dive in. Your scope uses the same addressing as the TDS520, but you have 16 chips vice 8 (see the 520B component manual). The address of the error U200 and the error location (738xxxx) point to Pipe-C (the third demultiplexer). Getting weird flashes can occur on ANY channel once you have a SRAM problem. On once 520D board, I ended up replacing 32 chips to finally get the errors to clear. (that's right, every single one).

The error location ends in "C" which when octaled down is 4 so it points to the 5th chip (fenugrec is correct there): it starts at 0 for ram chip 201 and ends at 7 with chip 208. Then the address lines repeat with 0 at 209 to 7 at 216. I'm sure Tek had a routine that narrowed it down to one chip, but the normal self-test reports the entire word, which is 4 bytes long. Thus, you end up with U205 and U206 on the first level and U213 and U214 on the second level. If you look at Page 15 on the 520B ACQ schematic, you can see that there are two full data lines (8 chips each), but only 64 address lines. Without some special Tek software you have to take 2 chips (odd, then even) at each failed address. You might get lucky with just one chip, but I played "whack-a-mole" with acq boards trying to do that.

I recommend that you do this to replace the chips: get new ones and remove the old ones using a hot rework or even a hot air gun. get all the old solder off the pads and try not to lift them. Use solder paste (like "chip quick") that you can get from - retailers. If you can practice putting chips in on some other old piece of gear to see how much paste to use, it helps a bunch. Don't overheat the ram chips and use static precautions as these guys are CMOS and really sensitive.

If you need more help, please send me a PM - I may even have the chips... good luck.

Strick

phaiduc
Posts: 6
Joined: April 25th, 2018, 12:10 pm
Country: Romania

Re: TDS744A Error message digDataFormatDiag

Post by phaiduc » April 28th, 2018, 12:36 pm

Many thanks for your help.
I think it is one of the 2 chips: U205 and U206.
I've got only once the error message:
ERROR: diagnostic test failure,
digSpeedMemDiag,
ERROR !!U206 MemAddr = 0x73a2b2a data = 0x35 exp = 0x25,
ERROR !!U206 MemAddr = 0x73a2aea data = 0x96 exp = 0x86,
ERROR !!U206 MemAddr = 0x73a2aca data = 0x5c exp = 0x4c,
ERROR !!U206 MemAddr = 0x73a2a4a data = 0xf9 exp = 0xe9"

However the digDataFormatDiag error appears during all acquisition tests:

ERROR: diagnostic test failure,
digDataFormatDiag,
ERROR!!in demux 200 ,i= 21 memBaseAdr 0x738002c= data = 200, expectedData = 1200"

I don't know what the i=21 could mean.
I have ordered two RAM chips and they should arrive next week.
I have the tools to replace them, just need some practice on some old boards.
I will start with U206 since it once gave the digSpeedMemDiag error and because it is located in the upper byte of the word,
where the data mismatch occurs: data = 200, expectedData = 1200"

I must also mention that the firmware is 1.1e

Best regards and once again many thanks for your kind support.

fenugrec
Posts: 77
Joined: January 18th, 2017, 3:51 pm
Country: Canada

Re: TDS744A Error message digDataFormatDiag

Post by fenugrec » April 28th, 2018, 5:43 pm

phaiduc wrote:
April 28th, 2018, 12:36 pm
digSpeedMemDiag,
ERROR !!U206 MemAddr = 0x73a2b2a data = 0x35 exp = 0x25,
Interesting, in this case it was able to figure out the error was in U206. It calculated the two digits "06" by doing

Code: Select all

((memaddr - 0x7380000 >> 1) & 0x0F) + 1 
If we apply the same calculation to your other error at 0x738002c, I get U207, but that doesn't seem to make sense. I'm not sure what "SpeedMemDiag" actually tests, but I'm fairly certain the address mapping at 7380000 isn't changed on the fly...

There may be a way to read/write to that memory from the service console port, if you have that connected ? By calling _readReg and _writeReg, it should be possible to target a specific address while probing the suspected ICs.

ERROR!!in demux 200 ,i= 21 memBaseAdr 0x738002c= data = 200, expectedDatai] = 1200"

I don't know what the i=21 could mean.
It's the # of the test pattern that failed; in this case 0x1200. There's a bunch of other patterns like 8000, 7FFF, 5500, etc.

The address of the error U200 and the error location (738xxxx) point to Pipe-C (the third demultiplexer)
Indeed; in the meantime I've looked at the _digDataFormatDiag code, and the mapping is

U198 : 7300000
U199 : 7340000
U200 : 7380000
U201 : 73C0000
i.e. there is 256kB reserved for each mux.
I must also mention that the firmware is 1.1e
Nice, I have the same version. Do you have a GPIB interface ?
For my personal interest I'd be curious to compare my NVRAM dump to yours (nothing to do with your problem)

phaiduc
Posts: 6
Joined: April 25th, 2018, 12:10 pm
Country: Romania

Re: TDS744A Error message digDataFormatDiag

Post by phaiduc » April 29th, 2018, 5:29 am

Nice, I have the same version. Do you have a GPIB interface ?
For my personal interest I'd be curious to compare my NVRAM dump to yours (nothing to do with your problem)
I have an Agilent 82537B GPIB to USB adapter.
I also have the Agilent I/O Lib Suite, but I don't know how to dump the NVRAM from the TDS744A.
I don't have much experience with IEEE 488.
Maybe you can provide me some hints how to do it.
Thank you.

phaiduc
Posts: 6
Joined: April 25th, 2018, 12:10 pm
Country: Romania

Re: TDS744A Error message digDataFormatDiag

Post by phaiduc » April 29th, 2018, 12:35 pm

I was able to read the NVRAM with tekfwtool with start = 0x0400 0000, len = 0xA 0000
Here's the contents for my TDS744A with firmware 1.1e
Please compare with yours.
Regards.
Attachments
NVRAM_TDS744A.zip
(74.3 KiB) Downloaded 522 times

strick
Posts: 110
Joined: March 22nd, 2016, 11:23 am
Country: United States

Re: TDS744A Error message digDataFormatDiag

Post by strick » April 29th, 2018, 5:43 pm

phaiduc,
Replacing the lower two chips may work, but may not - from page 1-13 of the TDS520B Component manual:
Acquisition Memory D. During acquire mode, Demultiplexer D writes to
Acquisition Memory D when eight samples accumulate. The full 64 bits are
always written in parallel. Two address buses allow two sets of memory to share
the 64-bit data bus on alternate 8ns cycles.

Also, the memory reported is always even (e.g. 738xxxx0 or 738xxxx2) as the data is in Words. The problem is, you don't know which memory write or read that it is accessing. The memory address is used twice with another trigger. If you can isolate the trigger and the write, you can - the chip, otherwise, you have a 50% chance of success.

Good luck, 50% is better than nothing. keep the chips you remove. If it doesn't work, put them in the the locations I listed earlier and you should solve the problem.

:) Strick

phaiduc
Posts: 6
Joined: April 25th, 2018, 12:10 pm
Country: Romania

Re: TDS744A Error message digDataFormatDiag

Post by phaiduc » April 30th, 2018, 7:19 am

Thank you very much for your suggestion.
I will start replacing with U214 which is on the underside of the board.
It has poorer cooling, so more chances to fail.

:) phaiduc

phaiduc
Posts: 6
Joined: April 25th, 2018, 12:10 pm
Country: Romania

Re: TDS744A Error message digDataFormatDiag

Post by phaiduc » May 20th, 2018, 8:11 am

Just an update.
The failed chip was U214.
Lucky for me, it was the first one from the list that I have replaced.
Now the scope works fine.
Many thanks for your help.

:P phaiduc

strick
Posts: 110
Joined: March 22nd, 2016, 11:23 am
Country: United States

Re: TDS744A Error message digDataFormatDiag

Post by strick » May 20th, 2018, 3:04 pm

Good! Happy to help out some.

Strick

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