[Test-Equipment] need some help

[Eric Haskell]

Brian,

A free operating and service manual :   http://cp.literature.agilent.com/litweb/pdf/04261-90006.pdf

A high quality professional scan of the manual for $15 US : http://artekmanuals.com/manuals/hp-manuals/

Good Luck.

Eric Haskell
KC4YOE

> Date: Sat, 19 Oct 2013 17:05:01 -0700
> From: cosmophone at yahoo.com
> To: Test-Equipment at mailman.qth.net
> Subject: [Test-Equipment] need some help
> 
> I have an HP4261A LCR Meter however I have no manual for it.
> 
> It seems to work correctly in that, when I measured a precision 1000 Ohm resistor, the display agreed exactly with the resistor value and, when I measured a 0.047uF silver mica capacitor, it read 0.0484uF.  The problem came when I tried to measure a 2.5mH RF choke.  While it read 2.4mH, it continually showed 'out of range'.  I manipulated the controls trying to get the out of range indication to disappear but it didn't.  After about five minutes the 1/2 Amp slow blow fuse blew and there was more than a wisp of smoke that came out near the front of the panel.  I pulled the cover off quickly in an attempt to see where the smoke was coming from but by the time I got it open I couldn't tell.  I pulled all the boards out of it including the display board and switch panel board but could find nothing that looked like it was hot except a white ceramic integrated circuit on the first board behind the board that drives the display board.  The metal lid which
>  seals the ceramic packaged chip looked like it had gotten hot but then it could just be oxidizaton.  After spending 30 years in the semiconductor industry I would think if this chip got hot enough to discolor the metal it probably would be toast however, when I replaced the fuse and turned the meter on again (without having the RF choke attached), there was no more smoke and the new fuse didn't blow although I didn't leave the meter on more than a minute or so.  Note:  I didn't try to measure any other components.  When the fuse blew the controls were in the positions below:
> 
> 1V drive
> L
> Auto
> 1 KHz
> DC Bias 0V
> 
> Also, the DC bias jumpers were connected to the measurement terminals.  I don't know if these are supposed to be connected for measuring an inductor but since I had the DC bias at 0V I didn't figure it would make any difference.  If anyone can shed some light on my problem please do.  I need to try to find an electronic copy of the user and service manuals.
> 
> Thank you,
>  
> Brian Harris, WA5UEK
> cell 214-763-5977
> email cosmophone at yahoo.com
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