Tek 1740a Blurry Screen

Hi everyone, I'm pretty new to the oscilloscope world so please forgive my lack of knowledge.<br> <br> I recently bought a Tektronix 1740a that was supposed to be in full working condition, but the screen is extremely blurry, even the menu options that show up on the sides are unreadable. I have a picture attached to show what the screen looks like. I've tried adjusting the intensity and focus controls but this is as good as I can get it.<br> <br> I also have a 1740 (non &quot;a&quot;) that I may be able to pull parts out of if needed, but the guts of the two look very different so I wouldn't be surprised if it won't help at all. The 1740 works just fine, but I want to get the 1740a working to use for audio signals, which the regular 1740 isn't capable of.<br> <br> Thanks in advance!

Hi,<br> <br> The 1740 and 1740A are waveform monitors, not oscilloscopes. They were especially made to work with NTSC signals, not general electrical signals like an oscilloscope and so have many functions and capabilities that aren't of much use outside of video signals.<br> <br> As far as I know, the A version was a complete redesign and so compatible parts might be limited.<br> <br> The unofficial TekWiki page on them includes more information on them, including manuals: https://w140.com/tekwiki/wiki/1740

The 1740a is definitely capable of processing audio signals as an oscilloscope and as a vectorscope. Both are defined in the manual and there are many videos of others using them in this way.<br> <br> Regardless, the issue is that&#160;<em>nothing&#160;</em>is clear on the screen, whether it's a waveform, oscilloscope, or vector, or even just the dialog options for the different menus.