Dave,
here is a hint!
If the JEDEC part number is not listed in the products part list description, use a HP Xref to convert HP part numbers to JEDEC (
www.jedec.org) part numbers.
For your Part, 26-0715 (18 is dropped).
Therefore, the HP part number for the Op-Amp is 1826-0715.
Using one of the HP Xref's, this equates to a NE5534!
The Original HP cross reference was posted in HP bench briefs regularly so there are quite a few different scanned copies around.
I also triple check part numbers before ordering/replacement, just to be sure!
This is my main Xref -
http://www.vk2hmc.net/blog/?wpfb_dl=7 (!warning 21Mb)
Be aware here are a number of different cross reference lists present in the file.
If the part is not in the 1st list, be persistent and keep searching.
Also, I find that this searchable excel spread sheet is pretty quick, accurate and fairly complete -
http://www.vk2hmc.net/blog/?wpfb_dl=6Actually, once you get used to the HP part system, it is quite easy to both remember and find the JEDEC part number if you have to.
--marki