Agilent 2000a / 3000a Oscilloscope NAND Recovery

This is very interesting. I just have one minor nitpick. Broadcom did not buy Avago, Avago bought Broadcom. They then changed their name to broadcom as it was more recognizable in the industry (while keeping their old stock ticker AVGO as that was more recognizable in the financial industry).

This is entirely a tangent but the rise of Avago from a minor second rate spin off from a spinoff from HP to one of the biggest and most profitable companies of the world (and one that is many times the size of current HP), is one of the most unusual mostly untold stories of the modern business world. It is a story of success (by Avago and Broadcom engineers and management) and incredible incompetence (by hp management that let them go for a pittance).

If you like this kind of content, I highly recommend checking out the Youtube channel 'The Signal Path' [1]. It has some fantastic technical teardowns and repairs of instruments, including really high frequency equipment.

[1] https://www.youtube.com/channel/UCKxRARSpahF1Mt-2vbPug-g

> the MSO adapter can accept low power signals up to 40v, but it offers no input protection when the host oscilloscope is off. Thus, if the DUT (Device Under Test) has a short of some kind near the area of probing, and the host oscilloscope is not powered, there's a good chance you've just damaged the Maxim MAX9201 comparators in the logic analyzer section of your scope! It's worth checking all 10 pins for voltages outside the MSO operational range.

Whoa, it's been a long time since I haven't used these tools but I learned now I was very lucky when using because I didn't knew this and didn't check the voltages when using the logic analyzer in the scope I had at the time from Tektronix - which I guess had the same type of limitations.

That NAND flash is a 128MB SLC part rated for 10 years of retention after 100K cycles. It's interesting that the datasheet says ECC is only "strongly recommended" and not "mandatory", but I guess SLC of the time, unlike MLC and later generations of flash where correctable errors are part of normal operation, was reliable enough that some applications didn't bother using ECC at all. It also recommends the 22-bit/256-byte SECDED ECC algorithm which originated in the earliest NAND flash with 256-byte pages and later became popularised by SmartMedia.

Flash memory bits wear out after 100,000 to 1,000,000 writes. Thus, file systems must keep track of the number of writes and have a strategy to avoid wearing out storage, such as by moving popular data. —Patterson & Hennessy, P.23 Computer Organization and Design 5E

That quote would've been true in the 90s or early 2000s at the latest. These days it's more like 100 to 10K cycles for most mass storage flash, with the majority trending towards the former.

I love seeing ridiculously technical investigations like this. It has zero relevance to me but it’s just sooo satisfying to see someone solve a tough problem.

It's so good and satisfying to see a person ply a trade to success. When I find myself stressed out for some reason, I like to do something I'm well trained at to help my brain kind of reset, which often gives me a different way of looking at what stressed me in the first place.

This is an awesome write up!

I have one of these scopes, with exactly this issue after a long period in storage. When I was looking into it a few years ago the failure mode was known but I couldn't find a recovery procedure. I'll need to give this a try when I get a few hours. I have been putting off getting a new scope in hopes that I could repair this issue.

// “You will need an oscilloscope, passive probes, …”

That’s my stop.

This engineer is determined! Built a test circuit to identify one part.

For anyone interested in the rotary encoder part, and how they work, I found this 7min explainer getting right into the details:

https://youtube.com/watch?v=S2BfGMqe3kQ

This guy knows his oscilloscopes.

This is an excellent writeup, it's refreshing to see detailed writeups that are quick to load

Woah, this is really cool to see here! Thanks for the post!