Hi Rich:
I don¡¯t have the manual here in front of me, but I did a lot of troubleshooting and calibration of the 2440 series. What you describe, reminds me of the current sense resistors going out of tolerance. If I recall these are very low value resistors, with tight tolerances. If they drift the PSU will start acting very similar to what you describe.
Hopefully, someone can tell you which resistors these are.
Rich Miller
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On Jun 27, 2018, at 1:03 PM, RichR via Groups.Io <choicetrans1@...> wrote:
I recently purchased a 2440 with a 4000 code, battery weak. Everything else appeared to be working. That was the only fault code. I replaced the two ram modules with new. The original were obsolete (DS1235BWL-120) so I purchased DS1230-100+. When I first turned on the scope everything powered up and there were plenty of fault codes so I started a self calibration. It never completed the self calibration. The scope went blank. I was able to power it up only occasionally until it stopped completely. It no longer tries to test when it is powered on the only lights on are the three GPIB lights. The screen will start with some erroneous dots and then go blank. I have tested the low power board and have some readings that do not match the schematics The voltage reading according to the power supply overcurrent check page 478 of the manual do not match. The voltages on the side board are correct so I am not sure where to proceed. I have attached a - of the readings I got from the power supply. Any help is greatly appreciated. Thank you, Rich
/g/TekScopes/files/015-0282-00/TEK%202440%20Power%20supply%20test/TEK2440%20Curret%20test20180627_12351992.pdf
