Star Wars vector problem

[edwoodjnr]

My Star Wars has just developed a vector problem while I was playing as shown in the video below. I have a spare board and through a process of elimination confirmed that the problem lies with the AVG board. I swapped all the RAM chips and AVG chip but the problem is still there.

This isn't a monitor deflection problem as my working board display is fine.

Gameplay and sound looks fine but there is a deflection problem from the AVG board. Has anyone seen this before and know what I should try next?

Thanks for any assistance, Gavin

 

[Alpha1]

What does test mode say?

 

[edwoodjnr]

I have the Vectorlabs ESB kit installed and it gives the known error of Program Rom Error at 1KL 3171. Apparently this is due to them not getting the checksum right. No other errors are reported.

I get all beeps ok but #14 is a boop which indicates a problem with EPROM 1F or 1M on the CPU board. I installed it a while ago but I think you have to remove these chips as part of the ESB kit install.

Having swapped a good AVG board over plus the little board from the ESB kit then it plays fine so it is definitely an AVG board problem.

 

[ColinD]

Gavin,

Bring it round in a few weeks and I'll go over it with the ABI.... I'm suspecting Ram round the AVG circuit, but not looked at these boards in ages....

 

[ColinD]

As Oll says.... go through the diagnostics for now (all the drawing test functions).... and report back....

 

[edwoodjnr]

Ok will do thanks Col.

Getting through the diagnostics is tricky as the vectors are all screwy, even on test mode. I will take a look later using this AVG board and the non-ESB working board.

 

[edwoodjnr]

Ok, I put the faulty AVG board with a working CPU and sound board and without the ESB kit and started it up.

Again the vectors were screwy and condensed into the centre of the screen as shown in the video above. Switching to test mode gave 16 good beeps in the sound test, no math box errors, no divider errors and no matrix errors. There were also no rom errors reported.

Not sure what to check next and maybe will need to take it to Col for a look

 

[trm]

That looks very similar to the symptoms of my dead AVG chip. Do you have another you can swap in, even for a test?

 

[Alpha1]

Ah Tim - yes the AVG chip, that is worth swapping as a priority.

 

[edwoodjnr]

Hi Tim, yes it was one of the first things I tried but no luck with this