New 3458A owner with questions

[rhb]

In a fit of severe TEA syndrome I bought a 1990 3458A with symptoms very nearly identical to the one that Shamir fixed in his video on SignalPath.

What  are suitable replacements for the NVRAM?  I know from experience with the Tek 11801 that it's often hard to get the right parts and may take months.  Purely a EOL support product line with small runs.

I don't plan to take it apart until I've received the NVRAM chips.  Are there other parts I should order before I embark on the repair?

Thanks,
Reg

[CurtisSeizert]

Get DIP sockets. I used the MillMax ones and they worked well. When I did a similar repair earlier this year, all the necessary Dallas chips were in stock at Digikey. Also, wasn't the source of the issue in his repair loose fiber optic cables? It has been a while since I watched that so I may be forgetting something.

[IanJ]

If you want to steer away from battery backed NVRams (Cal & Settings) then there is an alternative by way of FRAM IC's.
I made a wee YT Short a few months ago.
Gerbers attached.

https://youtube.com/shorts/Vz6c6m86O4c

Ian.

[rhb]

There was a good deal more than a loose fiber and NVRAM.  An opamp or two was also bad. and a voltage regulator pair.  I'll be installing sockets any time I unsolder DIPs.

I encountered a 6 month wait for the NVRAM in my first 11801.  The NVRAM will outlast me, but if I  can't get it now  have a solution.

Have Fun!
Reg

[Echo88]

Its Shahriar, not Shamir.

[ap]

Have you checked drift of the A/D board? Many units have that problem. There is an appnote for that from KS (AN18).

[rhb]

I've not done anything but power it up and verify it is as described.  I'm in the midst of a complete overhaul of my 1530 sq ft shop and constructing a 12' x 16' shielded room for my electronics lab.

I don't currently have the documentation and was hoping someone would post the NVRAM part number for current replacements available.

Once I replace the NVRAM I'll start investigating what other faults it might have.

Have Fun!
Reg