EEVblog Electronics Community Forum

Products => Test Equipment => Topic started by: tkamiya on January 19, 2018, 04:17:40 am

Title: HP8644A PLL and FLL errors
Post by: tkamiya on January 19, 2018, 04:17:40 am

I have an HP 8644A that displays the following error intermittently.

Trans VCO FLL OOL
NF PLL OOL

They usually happen when I make frequency excursions relatively fast.  Mssg indicator comes on and those are what gets displayed.  Other than this though, the unit itself appears to be functioning.  Oddly enough, I went through every manual I can find online and there are no mention of these errors. 

Has anyone seen these?

Title: Re: HP8644A PLL and FLL errors
Post by: tkamiya on January 19, 2018, 04:58:33 am

By the way, I just did the self-test and it concluded with result = 0.  It passes self-cal also.

Title: Re: HP8644A PLL and FLL errors
Post by: Tony_G on January 19, 2018, 04:48:10 pm

I can only find one reference to this one the HP Yahoo Group - In that case the A8 board was missing.

Maybe it is related to the power rails sagging? Trying hooking a scope up to the rails and seeing if you can reproduce the error.

TonyG

Title: Re: HP8644A PLL and FLL errors
Post by: tkamiya on January 20, 2018, 03:00:33 pm

That's just it....  not much info on the Internet. 

I'll check the power supply just in case.  Unfortunately, reliable reproduction is not possible.  It happens after a while, immediately, at all frequencies, and after lunch and dinner.  I hate intermittent issues.