For those who are struggling with the white dot problem, this was my fix.
I bought a faulty vectrex which didn't start up.
symptoms:
- white dot slightly off center in the middle
- no vectrex "buzz"
- light bulb from tube is glowing
- when touching the reset button the white dot moves
- Brightness pot behind vectrex is responding
- static and sometimes beeping sounds from speaker.
Solution:
- Checked voltages on the power board - 4.95 v, ground ,+ 4.88 v en -0.77 v ( aha! must be - 13v! )
- Checked voltages at the power switch: 1 of the 2 wires ( the wire going to -13v point at power board didn't have voltage continuity )
- fixed the switch
- Powered up the system and yes we have -13 v! , but still the white dot.......
- Switched the removable ic's from the logic board ( i have a second and working vectrex ), IC chip SY6522 was faulty.
Hopefully this will help out some with the white dot problem
In my case this was the solution.
The white dot problem is a common problem and many parts can be faulty.
Also good to mention:
- check the power and logic board for broken or bad solder points
- Swollen or leaking capacitors
- Clean the removable ic's and sockets and check for dust in sockets or corrosion (also check if they are firmly mounted )
- measure the 4 wire point on the power board
- check the x-y-z cable for correct voltages/ resistance
I,m not an expert in fixing Vectrex systems but every fixed problem is good to mention for the community!
Greetings,
Dennis