Service concerns for Tek 2246

[krish2487]

Hello Folks,

I ve recently acquired a Tek 2246 scope off flea bay for pretty cheap.
For what I paid for it, it was a pretty good deal. I have opened the scope to clean it up and to perform a general
checkup of the instrument.

The lithium battery underneath the top board reads 3.4 V.
This unit was last calibrated in 2011 and its manufacturing year was 1987.

While admiring the engineering of tek I noticed a couple of socketed windowed EPROMS on the top board.

I was wondering , if it makes prudent sense to just back up the firmware from the EPROMS in case of an emergency.

The scope is a bit off calibration in the horizontal  section. The test 1 Khz signal did not correspond to the horizontal divisions and
the time base setting.
I ll perform the service sometime this weekend.

Thanks in advance.

[grumpydoc]

The scope is a bit off calibration in the horizontal  section. The test 1 Khz signal did not correspond to the horizontal divisions and
the time base setting.

If it was calibrated in 2011 I would be more suspicious that the 1kHz was not quite 1kHz - the frequency of the test output is not usually accurate, it just has to have reasonably clean edges for the probe adjustment.

[nctnico]

Making a backup of EPROMs is always a good idea but chances are someone else already did that so you can download the images. Do check the firmware version though.

[krish2487]

@grumpydoc
Thanks. It did not strike me that the 1 Khz reference is out.
Will definitely check it out.

@nctnico
Thank you..
I ll keep posting the updates when I get around to actually servicing it this weekend.

[grumpydoc]

Thanks. It did not strike me that the 1 Khz reference is out.

The spec appears to be 1kHz ± 10%, 0.5V ± 2%.

As I said frequency accuracy isn't generally a feature of scope "calibration" outputs. They're not there to calibrate the 'scope but so that the user can adjust the compensation trimmer on an x10 probe and they only need to be "in the ballpark" for that.