Re: 2465A channel 2 problems

GerryR
 

That's the problem, in the normal mode, the 1, 2 and 5 volt ranges are all off, for example, a 1V signal on the 1V per division scale, displays as if on the 100 mV scale, etc., so I am assuming the attenuator is not switching for those ranges, but don't know if the relays in the attenuator, or the logic telling which tells them to switch that is bad. The digital readout shows 1V on the 1V scale but the display of the wave is as if it is on the 100 mV scale.
Is there a list of digital words for the different scales or a way to tell if the logic is bad?

GerryR

----- Original Message -----
From: "machineguy59 via Groups.Io" <machineguy59=yahoo.com@groups.io>
To: <TekScopes@groups.io>
Sent: Wednesday, October 16, 2019 6:48 PM
Subject: Re: [TekScopes] 2465A channel 2 problems


How does Channel 2 work when using the scope in the "normal" mode? If it seems about right (just not precisely calibrated) when measuring known voltages then the attenuator is switching.
On Wednesday, October 16, 2019, 03:31:47 PM CDT, GerryR <totalautomation1@...> wrote:

A little history first: Acquired the 'scope recently and everything was working fine. Old battery dated 07-87. Decided to change battery and took all known precautions, but somehow screwed up and requires re-cal. I have attempted re-cal, and went from a "Test 04 Failed 04" to a "Test 04 failed 02" which is a limit failure. Channel 2 "calibrates" up to the 10V input (cal 02), and I get a Limit 130 error, no matter what I try, so I assume that is my problem. In the non-calibrate run mode, the channel 2 input only works up to the 500 mV range (Hi-Impedance input with co-ax) and with the 10X probe, up to 5V. The display range readout works, but in the 1V, 2V and 5V ranges, it appears to stay in the 100 mV, 200 mV and 500 mV ranges, so it appears the attenuator isn't switching properly.

Is there a way to tell whether it is the attenuator, or if the proper outputs are not getting to the drivers for the attenuator relays, or is this still a calibration problem? I have no way to monitor a "word" from the processor at this point. I did try monitoring channel 1 at the drivers and comparing them to channel 2, but found it difficult to get any meaningful data. Any help will be appreciated.
GerryR

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