[acasha]

I have just unpacked my first projector - Marquee 8500 with rebuilt green and blue tubes.


Initially on power up there was a a horizontal flicker on the internal test pattern (about 1 Hz increase/ decrease in horizontal width about 10%) but this then settled.


The red and green patterns are almost in focus/alignment but the blue pattern is about 25 degrees sloping up. I think it must have moved during shipping.


Any suggestions on how to rotate the blue CRT tube?


Many thanks

Aaron Casha

 

[Tim in Phoenix]

Sir


It is likely that the blue scan yoke has rotated during shipment. First, null the zone convergence by pushing CONV, 1, 2 and exit with a save; make sure the memory is not locked, check UTIL, 1, 3 and select Unlock. Remove ac power and pull off the top gray covers. The blue CRT is on the same side as the power cord socket. Remove the metal and plastic covers from the tube shroud, they are held by phillips screws. You are likely faced with one of two scenarios; One is that the scan yoke (grey bell-shaped device at front of tube neck with white/red/blue wires at top) is still glued to the convergence yoke (device just behind scan yoke with allen head screw clamp behind it and orange/violet/brown/black wires atop) and that someone forgot to tighten the clamp; you would need to rotate the convergence yoke/scan yoke so the blue grid is level to green, then tighten the clamp, a 3mm metric allen driver is required. Scenario Two is that the convergence yoke is secure and the scan yoke is not glued to it; in this case you need to level the grid by turning the scan yoke, then glue it with hot-melt glue or silicone sealer. Be aware that the white/red/blue wires carry pulses of at least 1000 volts; do not touch the exposed solder points of these wires or any exposed copper windings. The pinkish wire is 34,000 volts to the tube anode, you are reaching amid Lethal Voltages. Before reinstalling the top covers try reseating the horizontal sweep board, it is in the metal sleeve next to the blue tube. If you are not technically inclined then you may want to call in someone experienced in CRT servicing.

 

[DoyleS]

When Tim answers, you don't get suggestions. You get detailed instructions along with warnings. He is the Master of the Marquee!


..Doyle

 

[Tim in Phoenix]

Well Doyle


I haven't gotten anyone electrocuted Yet!

 

[Gary Stevens]

Dead men tell no tales!


(Sorry, Dr. Tim, I just couldn't resist.)


-Gary

 

[Coyotes]

Hi Tim!

There is the third scenario mine, with OUR project in North Scottsdale).

That being the bell housing is glued to the CRT, the convergence yoke is tight, and the bell housing is skewed

Oh well, I have to get the porta-torch out and melt that goop.


Guys: Tim IS the MAN!

 

[acasha]

Many thanks Tim for your answer. I will try to have a go at this over the weekend.

I hope I will be able to tell the tale


Aaron Casha