[volt-nuts] Fluke 335A

[John Lofgren]

What other service have any of you performed on the 335A?

I have a beige unit, S/N 2710010, that was working for about a year and then developed a problem where the voltage won't stay stable.  After power-on with the metr in the TVM mode you could wath the meter slowly swing up and down the scale at varying rates, but never settling on a stable value.  I've put it on the shelf for about the last 6 years and haven't been back to it, since.

The troubleshooting flow chart leads me to the chopper oscillator section.  I've read through the procedure but haven't gone into the unit to attemp the alignment.  I am curious about the part of the procedure cautioning the user about going too far one way or the other in the adjustment and causing instrument damage.  Any comments or tips?

I'll also check the electrolytics while I'm in there.  Probably do that before the chopper aligment.


-John



-----Original Message-----
From: volt-nuts-bounces at febo.com [mailto:volt-nuts-bounces at febo.com] On Behalf Of gbusg
Sent: Tuesday, September 13, 2011 3:11 AM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Fluke 335A

I had similar, severe repeatability problems with the rotary switches in a 
very old (blue front panel) Fluke 335A.

By comparison I later acquired a much newer (late serial number with beige 
front panel) 335D having much more stable and repeatable output as related 
to its rotary switch settings.

Joe and Bill, did you happen to notice the date codes on the capacitors (and 
other parts) in your old 335As? (I no longer have my 335A, but I suspect it 
was made in the 1970 timeframe?  By contrast, IIRC, my 335D was made in the 
1990 timeframe.)

Greg