Tektronix 2445B On-screen text problem

Hello,
I recently acquired a Tektronix 2445B 'scope but the text display is faulty.

The display fails to give any meaningful information regarding timebase or volts/div settings. There are rows of dots along the bottom and various hyroglyphic characters appearing on screen.

I am able to remove the characters mentioned above using the readout intensity control.

The 4 traces work fine and are obviously fully controlable using the timebase and volts/div controls.

I can supply examples of the display if this would help. I recently found eprom sets for this model and wondered if replacing these may be a solution as I understand they hold calibration data etc.

Any advice would be gratefully received. Thanks for your help,

Larry

I have a TEKTRONIX 2445B, with an other problem, they don´t appears the trace.
Have you got this problem in the past?

No, the traces have not been a problem.

I let a local specialist look at it in January and he said it required a new computer board though.

We had that problem on one many years ago. It was the oscillator circuit that provided the clock for the digital circuit that does the readout. They had designed their own oscillator and the signal levels were marginal for driving the digital circuits.

I forget what we did to fix it, but it involved a component value change to improve the signal level.