The problem is dc offset.
On Mon, Jul 7, 2014 at 5:30 PM, Gerd <[email protected]> wrote: > Hello Ken, > > From what I remember of this circuit, R26 is for output stage bias. R6 is > for adjusting offset. By the way, which voltages are high and how much? > > The 5200 is an old beast, expect a lot of marginal electrolytics, carbon > resistors that have drifted well out of tolerance and even transistors that > no longer perform any where near what they originally did. > > Regards > > > On 07/07/14 14:56, Ken Goodhew1 wrote: > >> Hi all, >> >> I am currently repairing a Fluke 5200a ac voltage >> calibrator. >> >> After pulling cards in and out and soldering multiple wires on to test I >> now >> have the unit working about 98%. >> >> Anybody might have or know of where I might be able to obtain an extender >> card for this unit as it would make it a lot easier to fix the last >> remaining problem that I have, ie:- I have a dc offset voltage on the >> output >> of about 1mv when it should be +/- 100 microvolts. >> >> I am unable to adjust this with r26 adjustment on the power amplifier >> board >> as described in the manual. I have followed the troubleshooting guides as >> per the manual, as well as testing just about all the components around >> that >> particular part of the circuit. >> >> The problem appears to be that the input stage is not being turned on hard >> enough as all the suggested voltages for the input stage (Q1-2-3-4-5-9) >> are >> all too high. The supply voltages are all within spec. >> >> Anybody can offer suggestions? >> >> Sorry to put this out there in this group but I cannot find an online >> group >> related to fluke test equipment to ask. >> >> Ken Goodhew. >> >> >> >> --- >> This email is free from viruses and malware because avast! Antivirus >> protection is active. >> http://www.avast.com >> _______________________________________________ >> volt-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/ >> mailman/listinfo/volt-nuts >> and follow the instructions there. >> >> >> > -- > sig.html *Control Electronics Pty Ltd* > The home of Shiftmaster > Quality used test equipment > *Phone*: 02 9456 0736 > *Website*: www.controlelectronics.com.au <http://www. > controlelectronics.com.au/>* > Email*: [email protected] <mailto:admin@ > controlelectronics.com.au> > ABN 86 109 858 022 > ------------------------------------------------------------------------ > The email addresses in this message are not to be added to any database, > list, or mailing list without my prior explicit written permission. This > email and any files transmitted with it are confidential and intended > solely for the use of the individual or entity to whom they are addressed. > If you have received this email in error please notify the system manager. > Please note that any views or opinions presented in this email are solely > those of the author and do not necessarily represent those of the company. > Finally, the recipient should check this email and any attachments for the > presence of viruses. The company accepts no liability for any damage caused > by any virus transmitted by this email. > > _______________________________________________ > volt-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/volt-nuts > and follow the instructions there. > -- John Phillips _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
