I have recently re tubed an ECP 4000 with known good tubes from a 3000. Everything went well with all aspects of the machine lining up with little trouble. There is one problem left and I am unable to determine if is a fault, or a design flaw.
At this point I should say that the projector is level and square to the screen, the rasters have been centered on the phosphor area, and the yokes have been adjusted to match skew to the red tube (which has its original yoke, and therefore considered a reference.
This is a basic geometry problem.
It seems to be impossible to get geometry correct using KEY bow and Pincushion correction only.
The projected image can only ever be correct on three sides, the other having keystone distortion, as if the correction waveform is acting asymmetrically.
Obviously I can correct for this using green only convergence, but the quantities required produce unacceptable banding on the resultant image. (it seems to me that green only convergence is only of use for removing the smallest of errors before banding becomes a problem, and not really helpful in a "real" situation....a design limitation in itself ??)
Are there any adjustments which affect the symmetry of the keystone waveform so that I may cure this problem ? (it is almost as if I require a separate left/right keystone adjustment) or indeed may this be a problem with the Keystone module, or the waveform module itself ?
I am quite keen to resolve this, as in all other respects it is producing stunning pictures (much brighter and sharper than the sony 4200 it was meant to replace (although some of this can be due to the superior glassware in the ecp...)
Any help offered much appreciated....
At this point I should say that the projector is level and square to the screen, the rasters have been centered on the phosphor area, and the yokes have been adjusted to match skew to the red tube (which has its original yoke, and therefore considered a reference.
This is a basic geometry problem.
It seems to be impossible to get geometry correct using KEY bow and Pincushion correction only.
The projected image can only ever be correct on three sides, the other having keystone distortion, as if the correction waveform is acting asymmetrically.
Obviously I can correct for this using green only convergence, but the quantities required produce unacceptable banding on the resultant image. (it seems to me that green only convergence is only of use for removing the smallest of errors before banding becomes a problem, and not really helpful in a "real" situation....a design limitation in itself ??)
Are there any adjustments which affect the symmetry of the keystone waveform so that I may cure this problem ? (it is almost as if I require a separate left/right keystone adjustment) or indeed may this be a problem with the Keystone module, or the waveform module itself ?
I am quite keen to resolve this, as in all other respects it is producing stunning pictures (much brighter and sharper than the sony 4200 it was meant to replace (although some of this can be due to the superior glassware in the ecp...)
Any help offered much appreciated....