Vectrex - screen compresses slightly when moving joystick

[fugu]

Hi,

I just received my Vectrex which is a NoBuzz Version.
All fine, except one thing...
I have tried to capture the effect in a short video (link below), but I am not sure if this comes across well?

The problem is if any of my controller is plugged into 1st player and I move the Joystick, the screen becomes horizontally compressed.
This becomes very visible when text is displayed.

 

Checksum = 7ADB

 

If anyone has any idea of possible root causes, that would be really fantastic.

Many thanks for your help in advance.

Best regards,

Sven.

 

Vectrex.MP4

 

 

I have posted this already at Facebook, but with no response:

https://www.facebook.com/groups/104852679725118/permalink/612723958937985/

 

 

Edited May 15, 2017 by fugu

[+KylJoy]

Well, I believe you have a problem with an IC. I seem to remember that happening with one of my Vectrices (I have no idea what is plural for Vectrex) and swapping out one of the ICs alleviated that symptom. I cannot remember which IC though. Perhaps the field service manual would be helpful. It is online at several places. It is likely the IC related to analog inputs.

 

This is one of the reasons I have two of everything... component swaps for troubleshooting.

[fugu]

Hi KylJoy,

 

many thanks for pointing direction.

 

Can anyone help me which IC(s) could be the rootcause?

 

Many thanks in advance.

 

Best regards,

 

Sven.

 

[TomSon]

Hmm, I'm not certain that this is an IC issue - I've seen similar behavior in the past: the 7ADB bios version has a slightly

different joystick measurement routine to the older ones so it doesn't surprise me that some effect might happen on a 7adb

but not an older one. This is usually a non-issue depending on what happens afterwards.

 

I actually saw a behavior a .lot. worse which I had to specifically fix in an old VecFever menu a long time ago:

the 7ADB joystick analog measurements are actually fixed, there's a bug in the older bios versions,

but they don't zeroref just like the old ones, either, which I'd call a new bug - this is probably the culprit here, not the actual fix.