Sencore Champion CR-143 fault

[Fairlane500skyliner]

Hi all,

I tried using my Sencore CRT tester the other day, but was greeted by a burning smell when I plugged it in. Upon opening, I found that R1 (180 ohm) was burning up. I replaced it, but the new replacement started smoking almost instantly. Does anyone know what's going on with it, as I have no experience with CRT testers. Could it be because I switched it on without having a load (a CRT) connected?

Thanks,

Chris