I'm turning the scope on every day and so far it refuses to hiccup on the initial self test and everything is working perfectly including the calibration. You might say I should not brag about that or it will speed the arrival of a problem. But finding that illusive bug from a couple of weeks ago is exactly what I want. It has to appear first in order to fix it.
In the mean time, need to move on to other issues. And the next issue on the priority list is the Dallas DS1225Y with the embedded battery. First order of business is to determine the date of manufacture, which is printed on it as date code 9134d3. If I read that right in the Dallas spec sheet, it was manufactured in the year 91 (1991) & in the 34th week. If that is correct, this battery is still running after nearly 25 years! It's guaranteed for 10 years! So that needs to be replace ASAP.
Reading Dr. H. Holden's great report "Tektronix 2465B oscilloscope - - - ," dated June 2015, I decided to follow his lead and replace the DS1225Y with the ferroelectric FM16W08 which does not need a battery. But there is one issue with the timing of the /CE enable line. According to Holden, the scope is wired to assert the /CE enable at each address location, which is what the FM16W08 requires. While the DS1225 does not need that asserted for each address location, it will obviously work when it is. Therefore as luck would have it, the FM16W08 should be a drop in replacement, except that it's only available in surface mount. The existing DS1225Y is a DIP version soldered through the board.
The physicals of the surface mount issue can be easily fixed by ordering -
Adapter board # 28-650000-10 from Digi-key for $18.54
28 pin socket, to plug the adapter board into, # 828-AG11D-ESL-LF from Digi-Key for $2.34
FM16W08 from Mouser, to solder to the adapter board, for $10.29
The next challenge is to find a programmer to read the DS1225Y and then write to the FM16W08. Again, I followed Holden's lead and bought a GQ-4X Universal IC programmer along with the other items above. But I wanted to make sure this all works before removing the DS1225Y from the scope. The GQ-4X supports the DS1225Y, but does not support the FM16W08. So we set the programmer up for the DS1225Y with an FM16W08 in the socket. With the help of a neighbor friend who is more up on programmers, we were able to read & write to the FM16W08 using another set of cal data found on line that was copied out of a another 2465B. But it will only read the first address location which means it apparently does not assert the /CE for the additional addresses which, of course, is not required for the DS1225Y.
So- don't know how Holden got it to work. We went on line and found an older version of software for the GQ-4X thinking Holden might have used that one which may have toggled for each address, but that software would not run on my newer version of the Programmer. I had previously stepped the scope through the Hex codes in the internal test routines out of EXER 02 and hand copied them thinking that in the worst case I could manually enter the data into the GQ-4x to program the FM16W08 (it's a long list of codes, but not impossible). But that won't work if the programmer won't write to the IC. We also tried some trickery to no avail.
Next step was to contact the manufacturer of the GQ-4X. They confirmed all what we had surmised and said that if we had their latest hardware version (GQ-4X4), it has more flexibility and the FM16W08 can be easily added. The indications are that I have the latest version, not to mention that I just bought it. So, I'm going to contact them again tomorrow to confirm my version and see what's needed to get them to add the FM16W08 to their programmer.
In the interim, incase this will take too long, I may just replace the existing DS1225Y with another new one that I can program. Then switch it out (I'll be adding a socket) for the FM16W08 later.
So this is where the scope is now. It's certainly a much bigger project than I ever imagined when I bought it. But, it is an education. And reading all the entries on the internet about the pitfalls and should dos, has been a great help.