Tektronix 2445A: Repair/Restoration/Calibration

11393407_504943222988196_8837509473214264700_oThis is the Tektronix 2445A on my workbench, underside (belly) shown. This is the A1 board containing the attenuators for Ch1 and Ch2, and preamps for all 4 channels.

I’m doing voltage and voltage ripple measurements, as per Service Manual. So far, all voltages were within tolerance, though the 5V ripple is on the high side and exceeds what the Service Manual recommends. But even though, this higher ripple voltage shouldn’t cause the problems I’m experiencing with the scope (wrong reading for Channel1 measurements.)

Reading the Service Manual, I noticed there is a way to switch the scope into Diagnostics mode. This is done by pressing Delta-V, Delta-T and Slope buttons all at the same time.

Repeatedly doing these steps, I noticed my scope not reacting or doing anything. According to manual, the scope should display certain user prompts on the screen but on my scope, they’re not showing at all.

I know the buttons for the Delta-V and Delta-T works, because I’ve been using these cursors in the past to make voltage and frequency measurements. The Slope button, I admit I haven’t really used. It’s always shown (+), and doesn’t toggle to (-) when the button is pressed…. Hmmm……


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