Hi Corby, On 2020-01-06 23:02, cdel...@juno.com wrote: > Magnus, > > If you apply a +20V supply to the lamp connector you should see 125-150ma > unlit and it drops bit when it lights. I see about 1,23 V over the 10 Ohm resistor, matching up with that current. > Also measure from the lamp connector center pin to the outside conductor > with an Ohmmeter. > > You should have around 3.33K. The 1.33K resistor (in series with a 2.0K) > is a common problem. it can open up or rise in value. > > I usually replace this resistor in units I service even if it measures > good. > > I use a 1.3K 2% MOX resistor. > > Also check the approx. 12 Ohm resistor on the standoffs to see if it > opened up.
Both these resistors where good, but fractured. I already replaced the 10 Ohm resistor (put a pair of 22 Ohm resistors in parallel so they can handle the power better) and is about to replace the 1.33k resistor. Nothing else looked terrible bad and as far as I was able to quick-measure the resistor did not seem broken, but I consider replacing that regardless, but I will check it again. > > If you pull the lamp assy. you can place a spec-A lead and see the RF. > Should be approx 88Mhz. (not critical) Before opening up the assembly I sniffed the J16 connector for something in that neighborhood, but no. I forgot to sniff again with the hood off. However, I let it sit there for some time without any actual light from the lamp. I did see light coming in from the side and thought that this was the lamp, but no. > Once power is applied the lamp should start (cold) within a minute or > so, warm it starts fast. > > If you place a scope on A7 TP2 and with the lamp assy removed allow some > florescent lighting to fall into the interior you should see a large 50 > or 60Hz signal from the light falling on the photocell. I was considering doing exactly that, but I concluded that the lamp does not lit so I thought I would want to start with that anyway. Thank you for your input so far. It seems like I'm not completely off the mark even if I have yet to find the real fault of that rubidium lamp. I borrowed the A15 board over to the other broken 5065 in order to support another measurement campaign, and while that second 5065 is noisier that the 5065 that is operational (on its own) it was quieter than the OSA 3210 and 5071A cesiums. The aim is to repair both 5065s that is broken so I have three operational. Once they are all working, I will do a trim campaign on them. I was amazed at how much noisier (factor of 3-4 times) the older unit was compared to the newer. Phase-noise of the synthesizers is not stellar by any means, my 3325B is cleaner by far, and I only used a spectrum analyzer to compare them while the TimePod was busy doing other things. Right now the main goal is to get as much as possible online to see just what set of devices is able to make the TimePod eat into the noise and characterize the EFOS10... because it's a fun challenge and a chance to characterize things. It is also good to have those curves as reference as one measure things. Currently my best 5065A and a BVA is given a shot, but since the BVAs was brought online the other day, it is clearly drift-limited. I have 5 large rubidiums, it would be nice to have them all operational and see how they behave. Then I have cesiums to test... and OCXOs, and GPSDOs... yes, lab-time is fun again. Talking about GPSDOs, I have two home-brew GPSDOs that I've been firing up, one is build by late Lars Wallenius, and another by AE6RV GFS-6A GPSDO. The Trimble Thunderbolt seems happy right now, but my Trimble NetRS is not seeing any satellites. Cheers, Magnus _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.