Thanks so much, that's just the encouragement I need to crack open the RF section. I'll take a look at the electrolytic caps you suggest. Assuming that I find something, do you think it's worth replacing other caps in the area figuring that they will also go bad soon enough?
jeff John Miles wrote: > Never fear. I have seen this a few times, in a couple of 8566Bs that I have > owned as well as in some others. The YTO UNLOCK error always seems to come > down to an open electrolytic on the YTO driver or pretune DAC boards, under > the hinged plastic cover toward the rear of the RF section. > > Check power supply voltages first, then check ESR of all of the axial-lead > electrolytics on all boards under that cover. Then, if those areas are both > OK, go through the YTO calibration procedure in the manual until you either > successfully recalibrate the pretune/driver system, or reach a particular > step that you can't complete. > > -- john, KE5FX > >> -----Original Message----- >> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] >> Behalf Of Jeff Mock >> Sent: Thursday, December 06, 2007 7:38 PM >> To: Discussion of precise time and frequency measurement >> Subject: [time-nuts] HP 8566B repair >> >> >> Does anyone have any suggestions or advice about 8566B repair? >> >> I've had an 8566B for 7-8 years, it's been a faithful tool, never had a >> problem with it. It's reasonably clean unit that's never seen a tough >> life. It sits in the storeroom 90% of the time and is on my bench maybe >> 10% of the time. >> >> So, this week, after a 4 month hiatus, I've been using it on the bench >> and it starting producing a "YTO UNLOCK" message, the trace seems to >> basically work properly but is clearly unlocked and the trace will >> randomly slide to the left or right. The Yttrium oscillator is clearly >> unlocked. I'm hopeful that the problem is in one the control loops >> outside the oscillator module. >> >> I read the repair guide that Agilent kindly keeps on their website, they >> have some good instructions and narrow the problem to 3-4 modules, but >> I've never opened up the instrument and am a little apprehensive about >> making things worse. My hunch is that the problem is an electrolytic >> cap that has dried out over the years and has failed. >> >> Any suggestions for either self repair or outside repair and >> re-calibration is appreciated... >> >> In full disclosure, I also have a 70908A based spectrum analyser that >> that has much better specs, especially in microwave. It can completely >> replace the 8566B, but I'm quite fond of the 8566B, I can operate it >> blind folded, it's like an old friend and I would really like to fix it. >> >> > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.