Screen image pinched on sides?

[ahofle]

I believe this is a general monitor question.  I just got a Betson 27" multisync installed in my cab.  I have adjusted (sized down) the picture so that it is more like 24" to 25" or so (27" is just too big IMO).  Anyway, I noticed that on the sides of the screen the image is 'pinched' a little bit.  For example, in Joust when the ostrich runs across the screen, as he gets near the edges he gets skinnier, then fatter toward the middle.  I know this is usually an indication of bad caps but this is a brand new monitor.  Is this normal when sizing down an image?  Is there any adjustment that will remedy this?

[SirPeale]

Sounds like pincushion.  Can you show us a picture?

[ahofle]

Sure, I'll take a picture tonight.  I did mess around with the pincushion setting, but I thought it only adjusted the curvature on the sides.  Maybe I screwed it up though hehe.  I'll try that setting tonight and see if I can fix it.  Thx.

[modessitt]

I've seen this on older monitors before (like G07's) and can usually fix it by adjusting the B+ voltage a bit.  Or the horizontal oscillating frequency if there is an adjustment for that.  Haven't ever dealt with a Bentsen, so don't know what's adjustable and what isn't...

[SirPeale]

Could be trapezoid settings too.  Could be a lot of things.  Damn digital monitors have more settings than a nuke.

[MonMotha]

There is a horizontal linearity adjustment in service mode only.  If things are too fat on one side and skinny on the other side, that may need tweaked.  If things are fat in the middle and skinny on both sides, that particular monitor seems to just exhibit some of that.  If it's really noticable, it's possible that the trapezoid/pincushion/corner settings are out of whack, giving straight edges but incorrect geometry in the middle of the screen.

The service manual has a procedure for setting the geometry correctly that seems to go in an order which removes most of the interdependency between all the settings (and there's a lot, especially with the corner settings as well as trapezoid/paralleogram/pincushion/pinbalance).  Retroblast has it as a PDF.

[ahofle]

Wow, thanks all for the info.  It does seem to be skinny on both sides unfortunately.  I found the service manual, and it shows the service mode OSD, but with no descriptions of the icons (I think this manual was written by the 'all your base are belong to us' translator). 

Attached is a screen shot of the service mode OSD.
Is the icon by the red arrow the 'horizontal linearity' adjustment you mentioned?  Also I have no clue what 'HV' or 'AC' is for.
Thx again for the replies.

[modessitt]

Have you tried doing a factory memory reset to put everything back at factory defaults?  If this was caused by over-active adjusting, or even a problem adjusting to different resolutions, then that might help....

[MonMotha]

Going based on what I remember (the monitor isn't handy), the settings are:
First Row: Brightness (black level), Contrast (white level), H position, H size, V position, V size, pincushion, pinbalance, trapezoid, parallelogram
Second Row: High Voltage (unitless), ACL (luminosity), H linearity, two flavors of vertical linearity, H/V on-screen-display position, not sure, timing information
Bottom Row: Rotation (doesn't work on the Betson OEM model), top corner, bottom corner, H Moire, V Moire, OSD Language, Color Temp (white point), Degauss, not sure, not sure

The manual has a sequence of things for you to do to tweak up the geometry.  The order is chosen to minimize the interdependency between all the settings (as there's normally a whole bunch, which you'll find out if you try to fine-tune things).  As always, be sure to write down the original value of the control before changing things in service mode.  The user mode controls are simply +/- deltas from the service mode controls, and factory reset in user mode just resets them all to the middle (which means the service mode settings with no further adjustment).

[modessitt]

do a reset in factory mode, not user mode....I've seen that fix strange problems....

[ahofle]

Thx for the suggestions.  Well I tried the H linearity in the service mode and it didn't seem to help much.  I'm starting to think it's just the way this monitor is when you shrink the image horizontally.  About resetting, I assume that would be the 'recall' icon in the settings?  Does that reset for just the current resolution or all resolutions?  Anyone know how to do a complete factory reset with this monitor?