I was asked if it was possible to modify a Jupiter Ace so it would work on 60Hz televisions. The Ace does not have any preparations for this. But it is possible to do so as the Ace is made out of off-the-shelf components.

  A TV frame for 50Hz televisions has 312 lines. The Aces display is drawn on the first 192 lines and the vertical synchronization pulse is generated after 248 lines to center the display correctly. For 60Hz televisions a TV frame must be reduced to 262 lines and the vertical synchronization should be generated after 223 lines.

  I've found two ways to modify a Ace for 60Hz TVs. A quick and dirty one and a accurate one.

  The quick and dirty one is the simplest of the two. But also the least accurate and requires a TV with vertical hold and vertical position controls. It will reduce the number of lines per TV frame from 312 lines to 260 lines which is close enough to 262. But the TV picture might start to roll. When this does happen you must adjust the vertical hold control on your TV to stop the TV picture from rolling.

The vertical synchronization is not changed and this will cause the top lines of the display to disappear over the top of the TV screen. To get the picture back in the center the TVs vertical position control must be adjusted accordingly.

For TVs without the vertical controls there is a more accurate modification that is requires some more work and a integrated circuit 74HCT00.

QUICK AND DIRTY MOD

  For this mod all there is to it is cut pin 1 of Z20 (see picture) and solder a wire from that same pin (pin 1 of Z20) to pin 9 of Z10 (see diagram).

Note:
When cutting a pin make sure that it does not make contact with the PCB anymore and doesn't snap off too. It must still be possible to solder to the pin afterwards.

ACCURATE MOD

  For this mod you need a IC(integrated circuit) 74HCT00. This IC will have a small notch or marking to tell which pin is pin 1. When you hold the marking up as shown in the diagram. The top-left pin is pin 1 and the top-right pin is pin 14.

  First solder pins 3,4,5 of the IC together and then pins 14,13 and 9 as shown in the diagram. After that solder wires to all other pins and pin 14. Next you need to cut the pins of the following ICs on the Ace: pin 1 of Z20, pin 3 and pin 4 of Z21. See the picture for locations of these ICs. Make sure you cut these pins in such a way that they no longer make contact with the PCB. But you can still solder to them.

After this you can solder each wire to the pins as shown in the diagram. the 0V wire can be soldered to any pin 7 of the marked ICs and the 5V wire can be soldered to any other pin 14 likewise.

Your Ace will now work on 60Hz televisions.