Vectrex screen alignment

[James1760]

Hi, I was hoping to get some advice on a vectrex issue that my Father in law is currently trying to fix, he is an ex tv engineer but seems to be struggling  resolving.

 

The original fault on the unit was a delayed start when powering on. Once the switch was turned, it took around 5-10 min to get a game to start, even then sometimes the cartridge was ignored and the built in game started. He has since been through the manual and checked voltage on components and replaced a lot of the IC’s.

 

The unit now appears to power up instantly, as expected as the sound can be heard, and controller seems to be operational (button presses result in the game firing shots) but the screen is not locking the x & y. This issue has got progressively worse, to the point where the images are barely showing on the screen.

 

He has used the vectrex documentation to check voltages on various points. IC 301 has been replaced, and recently the 6522 chip. The attached diagrams show various other components that have been checked/replaced.

 

He seems to think this is no longer an analogue issue, but a digital issue. Does anyone know what component could fail to cause the unit not to lock the picture?

 

Thanks

 

[fiddlepaddle]

I'm no hardware expert, but I've read a lot about the Vectrex (and have one). There are others on here who know much more about diagnosing these problems, but thought I'd just mention that the X & Y focus are adjustable and need to be tuned, preferably with an acceptable diagnostic cartridge for best results. Also, capacitors are likely to need replacement, if you haven't done that yet.

[James1760]

I think my FiL just needs to determine what controls the x & y, all analogue components that would typically control all check out and have the correct voltages based on the workshop diagrams. Capacitors have also been checked and when needed, replaced but still no joy. He has also checked the crystals with an oscilloscope and all checks out.

 

His thoughts are that this is an electronic component that may have failed which is now preventing the screen to lock. The 6522 seemed a likely culprit, but this does not seem to have fixed the issue.