[proudx]

I cannot keep my tubes from drifting during operation. They do not stabilize at any point and continue to drift up to 4 hours. The tubes will drifit up and down horizontally across the entire screen very gradually. Temperature will accelerate the drift. The entire green tube will drift up and sometimes the blue will drift down as well as the red.


All values are between 30 and 70 for convergence.


Here are my observations for the past week for reference..


30 Minute warmup Time with white warmup screen is always initiated before making observations...


The green tube will move vertically upward over a 4 hour period. After the first 30 mins of warmup the green tube is slightly below the red and blue. After 1 1/2 hours they are lined up. AFter 2 or 3 hours the green shifts above the blue and red.


Now the funny thing about my observations is while green is the biggest mover, sometimes red or blue will move up and down horizontally as well.


What could be the problem. I am going to have to attack this problem one card at a time, has anyone seen this?


Thanks,


David

 

[Kieth]

I'm not familiar with the internals of your particular projector, but based on your description it sounds like you have a bad capacitor or IC somewhere.


Common Sense applies. LETHAL currents/voltages are in the unit, possible even after being turned off. If you do something wrong you could smoke your projector or kill yourself. As I tell fellow techs at work, "If the Genie Comes Out, don't blame me."


A technique I have used with electronics in general which are heat sensitive is to turn the unit on and immediately heat one board with a hair dryer. Heat it gently and see if it speeds the shifting process you are describing. If not, turn the unit off to let it cool a bit; then turn on and try again on another board with the heat. It might take 20 or 30 seconds of good hot air to get noticeable shift. Don't get things too hot because you don't want to introduce problems. (In most cases, boards being wave soldered are heated more than a hair dryer can do, making a hair dryer relatively safe. This is also why I don't recommend a real heat gun.)


Once you locate the board causing the problem, let the unit cool yet again, and repeat the process again to narrow down the section of board causing the trouble. Once narrowed down as much as possible, visibly examine that area of the board for obviously defective components like leaking caps, replacing as needed. If you found some bad components hopefully the unit will be fixed after replacing them.


Otherwise -


*Caution about the next procedure. Use only high quality freeze spray. Some cheap freeze sprays I have encountered contain excessive amounts of water and can introduce problems, even failures. Make sure your spray specifically states that it is OK for use on live circuits.*


- warm the unit up to normal temperature where the described drift is present. "Freeze" components one at a time in the area of the board you suspect is causing the problem until you narrow down the exact component causing the drift. You will be able to reduce the drift by freezing and re-introduce the drift by heating with your hair dryer. Sometimes there may be two or three components giving trouble, especially in the case of caps. Note that it might be possible to avoide the use of freeze by carefully repeating the heat method... Anyhow, once located replace the suspected component(s) or board, and - hopefully - Viola!


Good luck!



Kieth

 

[proudx]

So you are saying do not allow the PJ any warmup time at all, just turn on and begin with the hair dryer and looks for movement?


I can't seem to get anything to shift with the hair dryer. Maybe I am not getting it close enough to the boards or heating long enough. Or maybe I shouldn't blow on it with the PJ warmed up. The movement is very gradual, I mean 1/4 of an inch over 4 hours. I just don't wanna introduce problems, my hair dryer is very hot, 1750 Watts.


I am going to be able to swap cards out later this week, however I am burning some major hours on my tubes trying to troubleshoot this issue. 2 or 3 hours to look for it to stabilize. The quicker I fix it the longer my tubes live So any idea where to start? Power supply, Convergence board, etc?


btw, convergence is anything but friendly with my pj, could this be an indication to a bad convergence board?

 

[wireburn]

You have some out-of-spec capacitors on one or more boards, as Kieth mentioned. If you have a capacitance tester, you'll need to desolder them one by one and check them. Replace them with the highest quality caps you can find. You're going to want to check the bypass caps on the SMPS first, then go for the vertical and horizontal cards.


I would start looking for another 808 that is close to the same manufacture date so you have some spare parts to play with. It should be fairly cheap if you get one with burned tubes.


Good luck!

-Mike

 

[proudx]

check the SMPS first? what is the SMPS? The Power Supply Board.

 

[wireburn]

Switching Mode Power Supply, you guessed it.

 

[Kieth]

With the projector cold and when first turned on, blast the suspect board with the hair dryer. Alternatively with the unit warmed up you could spray freeze.


I personally dont worry about getting stuff to hot. Keep in mind that these board go through wave and sometimes surface solder machines (basically a pizza oven) and the components survive. Too hot in general = cant hold your hand on it - and it probably wont get that hot to exhibit the drift. While I lean towards it being a thermal issue of some sort...as wireburn suggests it could very well be a component which is out of spec and drifts from being used rather than heat. If it came down to it, swapping boards is far easier in most cases then testing all the caps, especially when boards are available...


Good Luck!


Kieth

 

[DaveInVA]

I had the same problem with my BD801. The horizontal would sometimes shift about 2 inches on the sreen during warm up. There was another thread about this not to long ago only for an 801. I fixed mine by replacing most of the capacitors on the power supply and its rock solid now (for a Barco anyways). The blue/green convergence hardly drifts at all now and the red/green is stable after 20 mins or so (depending on room temp etc) and the horizontal doesn't drift at all anymore. I tried to use 105 degree rated caps instead of 85 degree caps wherever possible and no low quality caps.


Dave

 

[proudx]

I replaced SMPS. This did not fix the problem. There is still 1/4 of an inch shift in the green tube. It seems that the green tubes shifts up or that the

red and blue tubes shift down 1/4 of an inch during 2 or 3 hour duration. It will continue to drift the longer the PJ is on.


What should I replace next?


I did notice some differences with the new SMPS board. With the new SMPS board I was able to set hsize to 20 and get the same horizontal width as with the old SMPS board set to 90, any idea why this happened?


Thanks,


David

 

[Vic C]

30 Minute warmup Time with white warmup screen is always initiated before making observations...

................................................QUOTE....... ............................................



I hope your not projecting a WHITE screen? Those tubes are problably toast.


I guess there were some out of spec components on that board causing you to over drive it to get needed results. I would go for the convergend board next. I have heard of failures on Barco convergene boards. Im not a BARCO expert and I couldnt tel you which one is the convergence board.

 

[proudx]

I tried a new convergence board today. re aligned the tubes, went though the entire setup. everything looked good.


But sure enough when I powered up today after 30 min barco screen warmup it drifted!


The blue and red tubes stay locked on to each other, but horizontally the Green tube had been drifted down across the whole picture like someone did a raster shift down on only the green tube. The longer the power is on the green tube will shift up again like someone is gradually doing a raster shift upward.


AHHH, this is driving me nuts. What is next, the V shift board?

 

[proudx]

Ok Guys I just got the green to drift into good working position with the hair dryer!


However I heated so many boards trying to figure out which was the culprit I am not sure which one made the green drift.


First I heated the Verticle and Horizontal shift boards, nothing moved, next I heated the power supply board, nothing moved.


Next I focused the hair dryer in behind the rear most part of the green CRT where it plugs into the chassis. This is when I noticed the green started to drift into place with the red and blues.


So this could indicate a couple of things.


#1 there is a something or a wire loss behind the green crt that makes the tube drift as it warms up.


#2 the h shift and v shift, power supply cards I warmed before needed a few minutes to kick in and make the green drift.


I think it is something to do with #1 b/c I actually watched the green shift into place as I blew the hair dryer behind the green crts rear most assembly.


What can be done to fix such a problem.


Thanks,


David

 

[mp20748]

David,

check the center cross pattern in the installation menu. All three tubes (colors) should align on top of each other. On the Barcos if that center cross is not aligned you'll experience drift (toe-in).


Also crank up the contrast and defocus the green to check the astimatism. Make sure the center cross is aligned and make sure that the astigmatism/centering is properly aligned. In other words the toe-in on the tubes should be set correctly and the image must be properly centered in the tubes (mechanically) BEFORE any convergence is performed.



Let us know!

 

[proudx]

I have run though the installation menu, set all three rasters

to 50 and aligned the center cross pattern. However it should be noted

that I cannot get the center cross pattern to align perferctly vertically

as I cannot adjust the verticle aim of the CRTS mechanically. However

horizontally the Cross pattern is perfect.


Is there a way to mechanically adjust the verticle aim of the CRTS so my

cross pattern will be dead on vertically as well as horizontally?


"Also crank up the contrast and defocus the green to check the astimatism. Make sure the center cross is aligned and make sure that the astigmatism/centering is properly aligned. "


How do I make sure the astigmatism/centering is properly aligned?


I have noticed that my red tube throws out a thinner line than my green and blue tubes.


I have found the board or whatever its called that causes the green to shift. When blowing the hair dryer on board number is 1076175 Barco DATA 120V. It is a grey piece of plastic that is wrapped around the Back of the Green CRT. Is this called the Neckboard?

 

[mp20748]

"I have found the board or whatever its called that causes the green to shift. When blowing the hair dryer on board number is 1076175 Barco DATA 120V. It is a grey piece of plastic that is wrapped around the Back of the Green CRT. Is this called the Neckboard?"


Can you do a picture? I'm not sure what you're refering to here. The neck board number should be: 761750 and it should be mounted on the chassis right above the tube, and connected by a wire/plug to the CRT. I'm curious as to what the grey piece of plastic is. If it is on the glass neck of the tube you could be refering the astig/centering ring.


You would need a manual to perform the astig/centering. That could also be the reason why your green and blue lines are larger. You'll need to do a complete setup, and if you follow the procedure in the manual you just might eliminate that proplem.


I hope this helps!

 

[MrHiEnd]

"I cannot get the center cross pattern to align perferctly vertically ..."


To get perfect vertical raster alignment you need to play with vertical adjustment pots.

The vertical adjustment pots are the two pots in the center of the vertical deflection board that have a small metal heads on them - they are thirty turn pots. The pot with the red splash of paint is for the red adjust the one below it with no paint is for the blue. The board is the third board from the left floor mounted or from the right ceiling mounted.


TIP: If the projector is floor mounted, take care to use a guarded screwdriver or a tweaker. Dropping an unguarded tool into the projector WILL short out the cards. Cover the metal portion of a small screwdriver with electrical tape exposing just the very tip if you don’t have a guarded screwdriver.


Cheers

Richard

 

[proudx]

here is a pic of part number 076175.


What is this. When I blow the hair dryer on it it makes the green tube shift upward the hotter it gets.

http://www.davidproud.com:81/pic.jpg

 

[Chuchuf]

David,

If you do the same thing to the others on the Red and Blue necks do they drift like the Green does??


Terry

 

[proudx]

Hi Terry, I am in Austin on business this week but will give the red and blue tubes a test with the hair dryer to see if they move as well this weekend.

 

[proudx]

back from Austin and back at the PJ. I blew the hair dreyer on the other 2 crt modules like the one in the picture and there was no drift. I believe it is a lose wire going into the module in the picture. AS the wire heats up the green drifts up.


More specifically tonight I blew the blow dryer directly on the wire going in to the module in the picture and watched an even faster green drift than before.


Does that module need to be replaced, or does the wire simply need to be reconnected/etc better?