[volt-nuts] 3458A - To Modify or Not To Modify?
wpgold3637 at att.net
Fri Nov 4 23:38:25 UTC 2011
Good information from Loveland on prices.
In My Humble Opinion ( IMHO ). The meter belongs to whoever owns it, not Agilent. If I choose to change the NVRAMS and put them in sockets, which I have done, then that should be good enough for them. The date codes would show that the NVRAMS are current and have a long life left. My experience with desoldering and resoldering again and again because you have to routinely replace a component will eventually cause a failure in the PC Board. I don't care if it is once a year or once in ten years.
Why HP didn't put the NVRAMS in sockets in the first place is beyond me! The same with the ROMs. Actually one of my meters has 6 ROMs in sockets, which makes sense. The other has the single ROM soldered into the PC Board, again why they didn't use a socket is beyond me. HP probably didn't think that these meters would be still in service after 20 or more years, and that a newer meter ( probably 9.5 digits and 0.1 ppm stability ) would have been developed.
There is nothing on the A5 board that will affect the ability to "cal" the meter. The A5 board is pretty much, if not all, digital. And if there is something else wrong with the meter then you will still have the IC devices in sockets on the A5 board regardless.
So if it were my decision I would unsolder the NVRAMS and ROM, put in sockets using the "machined" ( I believe that is the correct term ) type sockets, get a new ROM and put it in along with new NVRAMS, and then send it to Loveland for a calibration, letting them know that the NVRAMS are brand new so they won't have any "before" readings. But you don't really care about "before" readings anyway. They would figure out that the ROM is the latest version. With a "CALNUM 1" that would mean that the meter was "caled" at the factory before shipment and never has done since. I define the "machined" IC Sockets as those that have a round hole on top where the IC pins go in and a round pin on the bottom to solder into the PC Board. These are the best.
You asked for an opinion and this is just one man's opinion.
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