I have an 887AB (s/n 2513) that I acquired a few months ago that has a new Null Detector board that I'm curious about. The board is a (factory installed) null detector board that uses a single opamp, a Burr-Brown OPA-111. I bought a manual for this instrument from Artek Manuals that covers the serial number of my instrument, but there's nothing in the manual about the new null detector board (887A-4022, p/n 812610). If anyone has any information (a schematic would be wonderful), I'd love to get a copy. Thanks for any help Dave M

No manual but here is a youtube video on the unit. https://www.youtube.com/watch?v=EQRg8Ot5WDM On Wed, Feb 27, 2019 at 6:54 PM Dave M <dgminala@mediacombb.net> wrote: > I have an 887AB (s/n 2513) that I acquired a few months ago that has a new > Null Detector board that I'm curious about. > The board is a (factory installed) null detector board that uses a single > opamp, a Burr-Brown OPA-111. > I bought a manual for this instrument from Artek Manuals that covers the > serial number of my instrument, but there's nothing in the manual about > the > new null detector board (887A-4022, p/n 812610). If anyone has any > information (a schematic would be wonderful), I'd love to get a copy. > > Thanks for any help > Dave M > _______________________________________________ > volt-nuts mailing list -- volt-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/volt-nuts_lists.febo.com > and follow the instructions there. >

Hi Randy, Thanks for the post, but I had already seen that video. Nothing new there that I didn't already know. I used to have an older 887AB that had the mechanical chopper. I installed the chopper-stabilized opamp circuit that you developed and posted; it worked great in the unit. I traded it for the unit that I have now (didn't work at the time I traded, but the repair was easy - had a bad transistor in the +18V power supply regulator). The unit I have now is a much better instrument - less needle jitter, better long term stability. I've always been paranoid about having service documentation for all my equipment. Never know when it will be needed, and could be the difference between a good repair and having to junk an otherwise good piece of gear. Surely, Fluke must have supplied the correct manual with this instrument when it was sold. Maybe someone, somewhere, sometime will see this post and happen to have a good schematic for this unit. Thanks again, DaveM Randy Evans wrote: > No manual but here is a youtube video on the unit. > https://www.youtube.com/watch?v=EQRg8Ot5WDM > > On Wed, Feb 27, 2019 at 6:54 PM Dave M <dgminala@mediacombb.net> > wrote: > >> I have an 887AB (s/n 2513) that I acquired a few months ago that has >> a new Null Detector board that I'm curious about. >> The board is a (factory installed) null detector board that uses a >> single opamp, a Burr-Brown OPA-111. >> I bought a manual for this instrument from Artek Manuals that covers >> the serial number of my instrument, but there's nothing in the >> manual about the >> new null detector board (887A-4022, p/n 812610). If anyone has any >> information (a schematic would be wonderful), I'd love to get a copy. >> >> Thanks for any help >> Dave M