HP 4815A Vector Impedance Meter

[johnny_canuck]

This device performs well except for an intermittent SEARCHING light coming on.
I've fed in an external oscillator signal, but get the same result. The PLL circuitry is the problem.
I've reseated cards and reheated solder joints without success. Anyone had any experience with these oldies? Thanks.

Ken

[cncjerry]

I have two, one for parts.  The unlock troubleshooting is detailed in the service manual.

I love mine but it has failed several times.  Luckily having the parts unit bailed me out but I am running out of functional cards.  The reliability isn't up to the usual HP standards for some reason.  In checking the failed cards all of the passive components check out fine so I suspect there are leaky FETs.