[volt-nuts] Keithley 2182A

[Todd Micallef]

The repair was performed last November and my memory is bad, too many
projects since then. The two defective parts were the TF-245 and U626.

My symptoms were noisy readings across all ranges. I could not get them to
settle down even with the input shorted. I measured the TF-245 in-circuit
to see if anything was too far out to be in spec. I was certain that the
30K resistor between 5-11 was open, so I removed it and measured. There was
also another open 90K resistor between 7-8.

I also had to trace an input signal through the meter and it led to the
resistor array. I will try and find the actual in-circuit measurements
before the part was replaced.

I


Todd

On Sun, Jun 26, 2016 at 4:23 PM, Russ Ramirez <russ.ramirez at gmail.com>
wrote:

> Looking forward to your notes Todd. A bit more info on the repair.
>
> DCV1 is OK except for the 10 V range. A test voltage input of 100 mV
> appears on the input side of Q665 fine, but not on the output side in the
> 10 V range, however a DMM measurement is solid in the other applicable
> ranges. So this issue does seem to be completely isolated to the 10 V
> range.
>
> DCV2 input is fine through the path to the ADC (TP652) in all ranges, but
> the unit is not making a stable measurement. For example, a 9 V input reads
> between 8.8 V and 9.2 V on the 10 V scale. The same 9 V input to DCV1 also
> looks good up to TP652, on the 100 V range since 10 v is out it, and it
> reads a stable 9.002 V at that TP. Without a schematic, it will take some
> time to determine what is different after the TP652 point - maybe there are
> in fact 2 ADCs, but it's not obvious either way.
>
> Russ
>
> On Sun, Jun 26, 2016 at 11:16 AM, Todd Micallef <tmicallef at gmail.com>
> wrote:
>
> > I have to review my notes, but I know of the two bad parts that were
> > found, one was the TF-245. I happened to have a spare on hand. I will
> look
> > through any notes to get the other part number.
> >
> > Todd
> >
> > Sent from my iPad
> >
> > > On Jun 26, 2016, at 10:09, Russ Ramirez <russ.ramirez at gmail.com>
> wrote:
> > >
> > > Thanks Illya - very nice piece of work!
> > >
> > > Russ
> > >
> > >> On Sun, Jun 26, 2016 at 5:27 AM, Illya Tsemenko <illya at xdevs.com>
> > wrote:
> > >>
> > >> If you looking into repair or internals detail of 2182, this draft
> > article
> > >> may help: https://xdevs.com/fix/kei2182/
> > >> Keithley stopped releasing schematics and detailed information since
> > >> xxxx-series instruments due to IP issues.
> > >>
> > >> 26/06/16 18:08, Brian Smith пишет:
> > >>
> > >> Hello Russ
> > >>>
> > >>> It appears that there are neither a service manual nor a schematic
> > >>> available anywhere.
> > >>>
> > >>> My educated guess is that this is because the 2182A is a current
> model
> > >>> instrument. The newest production model keithley gear does not have
> > >>> associated service manuals nor schematics published. These appear to
> be
> > >>> treated as trade secrets.
> > >>>
> > >>> You can have your 2182A serviced by Keithley if it is in need of
> > repair.
> > >>>
> > >>> I had my model 2000 DMM that I bought from eBay serviced by Keihtley
> > for
> > >>> $560. They replaced the motherboard bringing the DMM up to brand new
> > >>> condition. I asked for and received the calibration data with the
> > returned
> > >>> instrument.
> > >>>
> > >>> best regards,
> > >>>
> > >>> Brian
> > >>>
> > >>>
> > >>>
> > >>> On Fri, Jun 24, 2016 at 10:38 PM, Russ Ramirez <
> russ.ramirez at gmail.com
> > >
> > >>> wrote:
> > >>>
> > >>> The service manual, or a schematic. I asked just in case someone had
> > one
> > >>>> from an original purchase. I also asked a friend who worked for
> > Keithley,
> > >>>> but apparently no one he knew had one either. Hard to find.
> > >>>>
> > >>>> Russ
> > >>>> On Jun 24, 2016 6:26 PM, "Brian Smith" <briansmith23456 at gmail.com>
> > >>>> wrote:
> > >>>>
> > >>>> What document do you need? Keithley publishes most needed docs.
> > >>>>> On Jun 24, 2016 12:59 PM, "Russ Ramirez" <russ.ramirez at gmail.com>
> > >>>>> wrote:
> > >>>>>
> > >>>>> Just wondering if any of you might have a PDF of the subject
> > >>>>>>
> > >>>>> Nanovoltmeter?
> > >>>>>
> > >>>>>> TIA
> > >>>>>>
> > >>>>>> Russ
> > >>>>>> _______________________________________________
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> > >>
> > >>
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