| Glossary |
| alternating white and black horizontal lines that |
| can be counted from the top of the picture to the |
| bottom. |
Vertical Scan Frequency | The number of times per second a display image |
| is written or refreshed. |
Vertical Scan | Reverses the image vertically for use with |
Reversal Jumper | |
| Reversal PCB. |
Vertical Synchronization | The number of times per second a frame is |
Frequency | transmitted to a video display screen. |
Xenon Arc Lamp | See Arc Lamp. |
Model 250 Service Manual |