John, Thanks for the reply.
I don't know the history, just got it. When first plugged in, Photo I and 2nd Harmonic go full scale then promptly come back to 0 (center). Supply indicates normally, Lamp Oven, Cell Oven and Osc Oven all go full scale and stay. After about 20 to 30 minutes, they come back on scale and seem to indicate normally as compared to what the manual says. 5 MHz indicates normally though it takes a few minutes for it to 'warm up' to the proper amplitude. 1 MHz and 100 kHz do not indicate when the Start switch is cycled until after 30 or 40 minutes of warm up. Then they come on scale normally. When hooked to a scope, at 50 ohms, their amplitude essentially disappears. I suspect a problem there. Still visible at 1 Meg input impedance. Control and Error stay at 0. So, I think all indications are normal except Photo I and 2nd Harmonic. I read about the cell flooding issue and how to deal with it in the manual but I was expecting Photo I to give an indication in the presence of cell flooding. Should there be an indication on Photo I in the presence of cell flooding? If not, then clearly I need to go through the cell flooding steps. J16 indicates about 19.987 VDC I did not measure the current at J16. I'll have to go back and do that. Joe -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of John Miles Sent: Tuesday, February 09, 2010 11:51 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] 5065A Problem Suggestions: 1) Was it working before? If not you may need to follow the cell-flooding correction procedure in the manual. Corby Dawson made an informative post about that phenomenon a couple of years ago, if you can find it in the archives. 2) If it was working but failed, check the +20V supply at J16 first. If the voltage at that jack is OK but no current is being drawn, the Colpitts oscillator that drives the lamp has failed. Nothing else will work until you open the RVFR and fix the oscillator -- which is possible but not much fun. Suggest checking the ESR of all of the capacitors on the A11 oven controller before you put it back into service. When I got my 5065A I had to replace a resistor on the oscillator board that had physically cracked from overheating. Both C23 and C24 on A11 were open; so were the same two 20 uF/50V capacitors on the battery-charger board. I don't immediately see how that could have caused the oven controller to run away, but it was pretty clear that it had happened at some point. Either way, if the lamp or cell oven current hasn't decreased within 20-30 minutes after turnon, you need to power it down and look for a controller problem. -- john, KE5FX _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
