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Discussion Starter · #1 ·
I came downstairs and tried to turn my projector on. It was working great last night. Red and green look great, but blue is not working right. It is showing a full blue screen, with 4-5 diagonal static lines. This shows both on internally generated and externaly generated screens. I have turned the g2 down on blue and that did cause it to dim out.


Other settings don't seem to do anything. Unplugging the blue source does not do anything.


What should I check???


(please be technical but detailed, I am not familiar with all of the different parts inside in terms of their names or locations)


Muchas gracias guys!


(I have powered on and off a few times, and there are no failure lights on the projector or power supply. Unplugging all sources does not shut the blue tube down, it still shows the same image.)
 

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Discussion Starter · #2 ·
I also took a picture of the display in the tube. Unfortunately I don't know where to host it from, so if you want to take a look ask me and I can email you a copy. 800k 640by420 image.


Again, the entire raster area is bright blue, with dark lines running through the raster diagonally. There is no image coming through at all, through internal or external sources just the full blue screen with lines.


Scot
 

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Scot-


You can attach a file up to 640x640 by using the "Attach file" field at the bottom of the "Post Reply" screen by clicking the "Post Reply" button about 2" below (instead of just the "Post Quick Reply" field at the bottom of this screen).


It'll upload to the AVS server and the attachment link will show in your post. But you'll have to increase the amount of JPG compression and save it as
 

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Discussion Starter · #4 ·
Done. I have reseated the hdm, and pulled the VIM and reseated the mini connector, but no dice...


Just wanted to add since this was taken straight into the lens. It only fills the raster area, not the entire tube face. The smudges you see are just from dust on the lens face, they are not actually on the tube and are not visable from a displayed image, but I had the camera directly up to the lens to shoot this so it is visable in the shot.
 

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Neck board or tube is dead is my guess.


Try swapping neck boards between blue and another color.


Troy
 

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Discussion Starter · #6 ·
What should I know about before swapping neck boards? Special HV concerns etc.


Anyone who has some step by step instructions, please send em this way, I would really appreciate it.


Scot
 

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Scot, The 30Kv high voltage is in the red anode wire and the 1500v is at the pins sticking out of the yoke going to the deflection boards. You don't need to touch either one to swap the neck board.


Just be carefull when you remove or attach the neckboards so not to stress the pins and crack the tube. Just be reasonably gentle and you'll be fine. Make sure you reconnect everything as it came apart. Double check the connections before you plug it back in and fire it up.
 

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Say Scot


You likely have either a failed blue neckboard, or the blue tube electron gun has shorted out. On the neckboard locate R23, a 33 ohm 1/2 watt resistor just between where the two black ground lugs plug onto the metal plate. R23 is mounted vertically up off the neck board and is likely covered in clear heatshrink tubing. R23 is in series with the cathode, and if charred, may indicate a shorted gun due to a cathode-to-heater short. Call me daytime if I can assist, 480 368 7434 weekends okay too.
 

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Discussion Starter · #9 ·
OK, I will be giving this a shot tonight. I believe the best way to do this is to lower the rear part of the projector on the hinge, then unscrew the rear cover on the tube. It is 2 screws with 2 wires on it.


I believe this will allow me to look directly at the neck board. The service docs are not what I would consider clear in this aspect. If I don't see the above problem, my plan is to swap my red onto the blue to see if the blue will fire up, if I do see the problem I will leave it as is and put a new blue tube on the list along with another neck board..


What I dont know at this point is what I will need to remove to pull the neck card off, and any hints for removing it. Please don't assume I know anything. I have seen what I think are the 2 1500v wires going into the tube area, but it was from above through the holes, and thats as close as I have gotten.
 

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Discussion Starter · #10 ·
Ok the resistor Tim is referencing looks fine to me. So I guess the chances are it is the neck board. Problem here is avax states you dont have to remove the 2 1500v connectors and I just dont see how to do it without removing the two? I see two hv connectors, the white ground, and the row at the bottom, but all of those must be removed to pull the board off?


Scot
 

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Say Scot


Nothing, nnnooootthhhiiinnnggg going to the neckboard involves 1500 volts, not never. The 14-pin connector carries voltages up to 85 volts, filament voltage around 6.3 volts, and some over-current sensing. The small coax line just above it is 500mv video from the input board. Above that on a single black wire, push-on connection, is G2 bias voltage, around 700-800 volts. The short white jumper onto the tube pin is G2 passed thru a resistor. The two black spade connections coming thru the holes in the sheet metal that contain the neckboard are ground lines from the tube bell. Another short white wire to sheet metal is a ground. All these must be unplugged, and replaced correctly, when swapping a neck board.
 

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Discussion Starter · #12 ·
Ok, cool. Well I got the neck board off then removed the neck board from my red. Plugged it into the blue and there is my image. All nice and blue...


So it looks like the neck board is the culprit.


Looks like I need to get a new one now. Anyone in the dc area have one that I could use for the superbowl? :D


Sorry about all the questions, I would rather ask than get zapped!



I don't see anything specific as far as board versions, but the projector was produced in 1996 and I have the cl449a chips on them. Should I worry about another one blowing out or just move on and get a new one that should last me years?
 

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It is highly unlikely you will get zapped with the power cord unplugged. As long as you do not mis-handle the big red High Voltage wires (Anode). The tubes can hold a charge and zap you through the red HV if you do not properly discharge them. This is only required if you need to disconnect them. Everything else is safe when unplugged.
 

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Discussion Starter · #15 ·
Yes you can. The tubes themselves DO hold a charge, which is why when replacing them you must discharge them before really messing with them.


The neck boards were relatively easy to remove.


Here are my steps:


1 Rotate the rear tray down. This is done by removing the screws/ground wires on the rear railing and letting the rear come backwards. It will stop at 90 degrees.


2: Remove the 2 screws on the rear cover of the tube. There will be more ground wires you must remove.


3: Inspect the board. The whole thing there is the neck board. On the bottom you will see a ground cable which must be removed from the housing below the board. You will also see a bundle of cables going into the board. I left this in on the board side, but unplugged on the motherboard side. Unplug the 2 single wire connectors, one going into the tube and a color coded one going into the board. Leave everything else since it takes some force and could break the tube!


3: Remove the neck board from the projector. The easiest way I could see is by putting your finger on the heatsync side of the top of the board, and grabbing the cable bundle on the bottom. Pull outward on that, after making sure it is slightly broken free. Mine were fine in this sense, so I cant say what to do if its frozen in place.


4: Remove the mini rca cable since you will not be putting pressure on the tube. Only remaining cables are the 2 black cables going into the metal assembly on the middle of the board. These were TIGHT on my board but with enough manipulation they came off.


Just do it backwards to put it back together and make sure everything goes back where it came from!
 

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Tim has neck boards available as do I.


They don't fail that often, you might see if you want to buy the modded cards off Tim for an ext abit of performance, I only stock the stock boards.


Curt
 

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Scot,


If you need to replace the NB, try and make sure you get one with the CL449A chips on it. That is the latest version. There was a lengthy discusion on this in the Anyone for some Marquee Maint thread.


Jay
 

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Discussion Starter · #18 ·
I did end up gettting a new neck board from an 8500 and it completely fixed the issue. In fact it looks better than before!


I actually got 2 complete and functional, but burnt, 8500 tubes with electronics. I am thinking about upgrading from an 8111 to an 8500 at this point. Just need one more tubes worth of electronics and a stigmator board. If anyone has this stuff, or knows where I can get it, cheap, let me know! :D
 
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