Electronics > Repair

TDS3014 adventures

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ytsejam:

--- Quote from: giosif on June 25, 2020, 09:58:35 pm ---Just to provide an update here that the Ethernet connectivity issue turned out to be caused by corrupt NVRAM - speaking of which, one way to detect that is if the MAC address of the scope's Ethernet adapter shows in the configuration screen as 08:00:11:01:02:03.
I obtained an NVRAM dump file from another scope and used it on this scope and now network connectivity has been restored.  :-+

Thanks to users YetAnotherTechie and Galen on the forum here for their help sorting this out!

--- End quote ---

Jusy FYI to the guys here based on my research.

My TDS3014B has a failing DS1742W as well, not yet completely died, since I can still read the MAC address as 08:00:11:xx:xx:xx on the network config page.
TDS3014B can still be powered up correctly, and I can set the time and date without problem, this means READ/WRITE mode for DS1742W is allowed since Vcc acrossed the Vpf.

However, the MAC address can not be read by CPU in this case, which also caused the ethernet connection fails to work.
This is really odds to me, if the DS1742W can run into READ/WRITE mode, then the MAC address should be able to read by CPU.
I then install another working DS1742W from another TDS3014B of mine, and now ethernet connection works well.

I suspect that maybe there might be a period during boot up, the DS1742W can not be read since Vcc is not yet across the Vpf limit,
which causing the MAC address is not read correctly.
So, I give it a try by soldering a CR2025 to pin 24 and 7 of the almost-gone DS1742W, and keep pin 24 lifted (so DS1742W is powered by CR2025 instead of Vcc),
and install it into the IC socket on TDS3014B.
I think this should keep DS1742W powered by the CR2025, so that it is kept in READ/WRITE mode.
But the result is the same, after powering up TDS3014B, the MAC address doesn't work still.

So I'm curious, why the MAC address on an "almost-failed" DS2741W can not be read successfully while the date/time is well read?

ytsejam:

--- Quote from: sicco on February 23, 2021, 06:20:00 pm ---Start with power on reset while pressing B TRIG key. That re-inits some. But not all. The Ethernet bits are tricky.
Hex dumps or binary files have been posted on this forum. Maybe not for 3012-b exactly, but give it a try.

--- End quote ---

The TDS3012B.hex posted has been replaced with a JPG picture.
Try to rename the suffix from hex to jpg.

sicco:
On the older  TDS3000 no-suffix, the MAC address does not reside in the NVRAM, but on a flash rom on its plug-in board TDS3EM. But also there, for Ethernet to really work, it does matter big time what else is in its NVRAM DS1742W. Settings related to DHCP yes/no, subnet masks etc. For the -b models it might still be the case that the MAC address is not in the DS1742W. But other Ethernet settings for sure will be in the NVRAM.

Even though the scopes can see that NVRAM is bad (they will say so at 38400,n,8,1 on the first ttl serial port while booting up), and even though it then reinitialises to default settings like one channel only) it fails to properly set those Ethernet values. Only way to get Ethernet working again is to program NVRAM with known-good data, as you did. Same for holding down B TRIG while booting: it forces to re-init  most of the NVRAM but fails to re-init the Ethernet settings bits.

YetAnotherTechie:

--- Quote from: ytsejam on March 06, 2021, 07:12:27 am ---
My TDS3014B has a failing DS1742W as well, not yet completely died, since I can still read the MAC address as 08:00:11:xx:xx:xx on the network config page.


--- End quote ---

"Its dead Jim"

A scope with a corrupted or cleared NVRAM will still show a seemingly correct MAC address in the config page. That address doesn't work, and it's not being used by the scope. The only way to have a correct address is to program the NVRAM correctly.

ytsejam:
Thanks YAT and sicco for the response.

Get it fix is not something what I was after, just curious why.
I'm pretty sure that MAC address is stored in the NVRAM, if I swap the DS1742W with a new one, MAC address shown in the network config page is all zero.
BTW, IP/subnet mask/ gateway settings are stored in the flash instead, that's why even if you swap the NVRAM with a new one, IP/mask/GW are still there.

But, sicco did remind me a point related to DHCP.
Actually, the real issue is the BOOTP instead of DHCP.
BOOTP allows you to boot the system from network before loading the OS, and the scope needs a MAC address for that at the very beginning of booting process.
Which means MAC address will be read very early, and if at that moment, the NVRAM is not yet powered up, or entering the R/W state, it relies on internal battery to work.
I think this might be a reasonable explanation.

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