Hantarex 9110 image slightly tilted, how to fix?

[truffelzwijn]

Finally I had the courage to replace all electrolitic caps (and the fan) on my MTC 9110 and indeed the picture quality has improved greatly. The horizontal lines are straight allright but they are not completely horizontal. The complete image is tilted about 0.5 cm horizontally. I was hoping that changing the caps would fix this, but it didn't  I'm going though the service manual (
http://www.cityofberwyn.com/manuals/MTC9110.pdf ) but I can't find any controls for tilt/rotation.

Is there a way to fix this? Thanks!

[grantspain]

if you mean you entire picture is slightly twisted then you will need to do manually adjust the yoke

[truffelzwijn]

Thanks, and yes, the entire picture is tilted. I don't have a digital camera at the moment, so I made this example. How would I go about manually adjusting the yoke? That seems a lot more complicated than just turning a pot.

[truffelzwijn]

Just googled 'adjusting yoke hantarex'......Does this mean that I'm just going to have to live with it?

The MTC9000 features a very sharp and colourful display that is that is not found on other monitors. The MTC 9000 uses a RCA picture tube, a main feature which can be seen by looking at the neck. The purity and convergence ring assembly that is normally found just behind the yoke has been replaced by a non-adjustable ferrite sleeve. Instead of using a set of six magnetic rings to manually converge the picture tube, this CRT is converged by a computer during assembly. After adjustment, glue is injected between the yoke and the picture tube to hold the yoke in place. Once applied, the yoke cannot be removed! It becomes an integral part of the picture tube. The ferrite sleeve is then selectively magnetised by computer controlled electromagnets so that the red, green and blue beams from the electron gun are precisely aligned. This replaces the purity and convergence ring assembly, and eliminates the possibility of ending up with a poorly converged monitor.
http://www.coin.demon.co.uk/monitor.htm

[grantspain]

well all depends on if you have a bonded yoke or not,i seriously doubt you have a bonded yoke on that age crt

only way to tell is a photo of the yoke assembly

[truffelzwijn]

I just borrowed a digital cam to take some pics of the neck of the tube:

[grantspain]

well its not a bonded yoke BUT it has anchored glue points so not easy to rotate
another option is to lossen the bolts on the crt frame and see if you get enough movement from those

[truffelzwijn]

Ok, I studied the assembly a bit and I don't think i can get enough movement from the four bolts. They look mighty tight and are filled with a yellow resin.

If I loosen the bolt on the neck of the tube (big arrow), will I be able to rotate the yoke? It seems 'clicked' behind a number of plastic tabs (small arrows), but free to move around it's axis.  I don't see any other parts holding the assembly in place (or is this were the glue comes in?).

[grantspain]

i don't think you will get the movement and you could damage the neck,it is a bonded yoke-i did not look close enough earlier

[truffelzwijn]

Thank you for your help, Grantspain. Not the answer i was hoping for, so I guess I just have to learn to live with it.

[grantspain]

the bolts i referred to earlier are the crt fixing bolts on the front of the monitor,you can loosen them a little and reposition the entire crt itself

[qrz]

some of the larger screen (crt type) RCA's had a circular coil for "rotation"
don't recall if it used a modulated drive signal or dc...
gonna need to pull out some prints to double check . it could be your answer for that bonded yoke .

[MonMotha]

Most monitors I've seen with rotation coils are on digital monitors.  The coil is fed effectively DC via a filtered PWM coming from the micro.  It may be possible to install such a rotation coil and play around to get the current right to null out to rotation.

Or you could just live with it.