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Beamracer power requirements
Thanks for the inputs, looks interesting.

Quote:Instability can happen when playing a game, it will randomly crash, graphics will go bad, etc. I've noticed from past experience going in and out of the U2 menu will eventually trigger some sort of glitch. Sometimes it takes a while, sometimes it happens first go. Sometimes going in and out of the menu will clear the glitch and it will look normal again and sometimes it will just wedge harder the more times you do it.

Just to clarify - does it mean that the glitches can only occur _after_ entering U2 menu at least once? Or that entering menu is just increasing the likelihood of crash/glitch, but is not strictly necessary?

I have been experimenting most of the day with Ultimate-II Plus 3.6a (115), a barebones 250425 board, BeamRacer, and a variety of power sources. I was repeatedly (>100x) entering and exiting U2 menu from the boot screen, with following results:

- two different original PSUs: no issues with and without BR,
- externally provided +5V (bench PSU): one screen memory corruption event (with no BR inserted at the time),
- externally provided +5V with undervoltage: the lower the voltage, the easier was to create a corruption, with 4.3 V "succeeding" in just a few attempts. I wasn't running careful statistics, but it did not appear that the presence of BR was making any difference,
- original PSUs using low-quality connection (see the photo): having jumper wires and hook clips leading from the PS plug to C64 power socket was producing screen corruption around once per twenty menu enter/exit events. (This setup corresponds to about 4.7V on +5V pin, but also adds poor ground).

The screen and color ram corruption were relatively mild, but I'd expect that having a demo/game running while memory corruption is taking place could be much more impressive visually. EDIT: after testing with a demo, it indeed does blow up spectacularly.

Things to do:

- please measure PS voltages while computer is powered on, ideally at power socket pins,
- please try another power supply, if possible,
- if U2 is not stricly required to cause a corruption, please remove it and see if problems persist,
- please remove SIDFX and see if there is change in stability, 
- please download and run VSP Lab with and without BR inserted, to see how susceptible to VSP bug your machine is (,

While it does not appear that the socket situation you describe is solely responsible for the instability, it can certainly be a part of the problem. Can you see if touching/nudging the BR while the computer is powered on causes any visual glitches and/or crashes?

Also, what is the make of your PS?

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Messages In This Thread
Beamracer power requirements - by bodgit - 2022-01-01, 05:29 PM
RE: Beamracer power requirements - by laubzega - 2022-01-02, 07:48 AM
RE: Beamracer power requirements - by bodgit - 2022-01-06, 05:45 PM
RE: Beamracer power requirements - by laubzega - 2022-01-08, 02:45 AM

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