Computer Nerd Kev


Projects > Scopetrex

Scopetrex Build Notes/Modifications

Sorry, I couldn't get a good photo of the oscilloscope picture

The Scopetrex is a project by Tube Time for recreating the original Vectrex circuit on a modern PCB using components that are more easily available today. It is designed for displaying on a cathode-ray oscilloscope with an X-Y mode, or other vector display. Construction details, PCB layout, and schematics are at GitHub.

This page breifly documents some modifications and observations from my own build. I'm also selling PCBs for the main board, along with sets of all the components which aren't available from Mouser, at my OmberTech online store.

In some cases I attempted to stick to the original parts list from the Vectrex service manual in preference to changes made in the new design. Many choices were based on what parts I had available, so they're just documented to show that the substitutions are an option.



Underside of assembled circuit board showing rewiring of U204 and U201 connections to support V62C64P15L RAM chip and 27C256 EPROM

Additional resistors required for VecAdapt compatibility if a YM2149F sound chip is used

Neither of my X-Y capable oscilloscopes were sensitive enough on their Z-input for blanking to work effectively. One, which specified 40V blanking signal, fails to blank the trace at all. The other almost works with the brightness adjusted just on the threshold of visibility, but the centre-spot is still clearly visible and raster text is barely readable. A buffer circuit which increases the voltage of the Z signal should solve this problem, though as both 'scopes require a positive signal for blanking, this would require an additional voltage regulator on the scopetrex board. For me, the second 'scope works well enough for my purposes anyway. In other respects the display seems good, and equivalent to a Vectrex, besides the obvious reduced size.


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