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Discussion Starter · #1 ·
On my G70 with VDC rebuilt tubes I am getting a weird pulsating in the blue tube. The image and tube brightness will pulsate brighter then dimmer about 10? cycles per second after the pj is on an hour or so. The anomaly always happened when I was out of the room and was putting the projector into shutdown and error 39. Now I have had a chance to personal observe the pj while this is occurring . The projector stays on but I have to cycle the power off then back on to get rid of the pulsating.


Curt's first choice was the C block on the blue tube and we went ahead with long distance email trouble shooting. I have rotated the C blocks and the problem remains with the blue tube only. What the heck could be causing the intermittent pulsating?
 

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Quote:
Originally Posted by matrix /forum/post/19576774


Curt's first choice was the C block on the blue tube and we went ahead with long distance email trouble shooting. I have rotated the C blocks and the problem remains with the blue tube only. What the heck could be causing the intermittent pulsating?

if it's not a neck-board then PA board.
 

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Discussion Starter · #3 ·
PA board? Not good to hear. What other boards are specific to the PA to do a PA board swap? Or what other boards would I have to ship with the PA to Curt for a fix? I know the PA is specific to each PJ and voltage calibrations on other associated boards.


The PA was the board I posted about last year that was sagging in my PJ from excessive heat.
 

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When replacing old PA board The new replacement PA board usually requires Calibration with the E board for A matched set.. Note that it requires A special extention board

to perform the necessary adjustments..


Curt knows all about the above & would need to perform the necessary calibration..


Hope this helps,

Cheers..
 

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As Draganm suggested, I would look at the neckboard first. Swap the questionable one with another color and see if it follows the board.

I would not dig deeper into the chassis unless I had to. In fact, before I would swap neckboards, I'd wiggle or flex the one in question to make sure it's not a bad connection between the tube and board. The neckboard might just need to be removed and re-seated a couple of times to clean contaminates from the tubes pins.
 

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Discussion Starter · #6 ·
Quote:
Originally Posted by stefuel
As Draganm suggested, I would look at the neckboard first. Swap the questionable one with another color and see if it follows the board.

I would not dig deeper into the chassis unless I had to. In fact, before I would swap neckboards, I'd wiggle or flex the one in question to make sure it's not a bad connection between the tube and board. The neckboard might just need to be removed and re-seated a couple of times to clean contaminates from the tubes pins.
The first thing Curt had me do was swap the neck boards. I would think taking the neck boards on and off 3 times and rotating them between all three tubes would eliminate a bad connection on the tube pins wouldn’t it? But as I explained to Curt that is exactly what the problem looked like, a bad connection or intermittent one maybe in the blue tube video signal.


My thought is the PA board is overheating due to the warp or sag in the board I noticed earlier this year. I have since corrected the warp and taken precautions against it happening again but can’t help think the two problems are not related. When I got into the projector last week the PA board seemed to be running hot in my opinion. I can get some temp readings if anyone would know if the temps are within the norm.


I guess I could keep[ using the projector the way it is until something gives out and I have a smoking gun. With the cost of shipping the whole thing to Canada versus putting that money towards a good digital makes me wonder what to do. The projector still throws a great picture and only has 800 hours on the tubes since Terry helped me install them and then did his thing on the setup. No wear on the tubes and rock solid until now.
 

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I don't see in this thread where you said you swapped the neckboards around already. You know you have a problem with board sag. I don't know how hard it is to remove that board, but I would pull it and carefully inspect it for cracks and or bad soldered joints. Who knows, you might get lucky and spot something. Over heated areas on circuit boards are pretty easy to spot.
 

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I don't think it's the PA board since this is problem specific to one tube. About all I can offer is to take the green tube out and put it in place of the blue tube. The HV lead is too short to put the blue tube in place of the green, but take out the blue tube, put the green in. You'll need to take the main yoke off the blue tube and leave it connected to the green circuits (or stuff the blue tube in the green location, hook up everything except the HV wire that's too short.


if the green tube starts pulsing, suspect the A board (RGB input board), if the green is solid in the blue location, then I'd suspect the blue rebuild.
 

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Discussion Starter · #9 ·

Quote:
Originally Posted by stefuel /forum/post/19584173


I don't see in this thread where you said you swapped the neckboards around already. You know you have a problem with board sag. I don't know how hard it is to remove that board, but I would pull it and carefully inspect it for cracks and or bad soldered joints. Who knows, you might get lucky and spot something. Over heated areas on circuit boards are pretty easy to spot.

C blocks have gone all the way around the block, swapped three different ways. I did remove the PA today and looked very carefully at all the solder joints, connections, evidence of overheated components and cracked PCB. All is well with the visual inspection. The board is no longer warped after my shim job or little legs of plastic I installed on the leading edge of the board last year to help support the board.


Quote:
Originally Posted by Curt Palme /forum/post/19584372


I don't think it's the PA board since this is problem specific to one tube. About all I can offer is to take the green tube out and put it in place of the blue tube. The HV lead is too short to put the blue tube in place of the green, but take out the blue tube, put the green in. You'll need to take the main yoke off the blue tube and leave it connected to the green circuits (or stuff the blue tube in the green location, hook up everything except the HV wire that's too short.


if the green tube starts pulsing, suspect the A board (RGB input board), if the green is solid in the blue location, then I'd suspect the blue rebuild.

Curt, I just got home and my son said the blue tube was jumping out of registration by about eight inches or so but would go back in line with a repower of the PJ. I have not seen that before. Does this give any more clues for a direction to pursue?

I hate to take the tubes out and swap. I had 2 extra sets of duds and sold them a couple of years ago and now I wish I had held onto them. Maybe I can find one for sale at a reasonable cost to try a tube swap.
 

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I think the registration problem is completely different, that's your convergence board dying. I'd try the physical tube swap first. I do have a couple of toasted tubes here, but swapping positions within the set is about as easy.
 

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Discussion Starter · #11 ·
Curt, I am getting ready to dive into a tube swap this morning.After turning the projector on the blue image has in fact jumped down about eight inches as my son described. On the blue tube face image are wavy diagonal white lines. The blue tube will remain lit when I press PIC MUTE on the remote and the lines are still there but no video image. The red and green do mute. After seeing this I am starting to agree there is more going on besides the blue tube.

Take a look at the attached photo of the blue tube through the lens. The dark band is actually not present, must be the camera trying to decide how much light to register.
 

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Quote:
Originally Posted by matrix /forum/post/19587015


Take a look at the attached photo of the blue tube through the lens. The dark band is actually not present, must be the camera trying to decide how much light to register.

No it's the tube retrace. Some digital camera's, like my POS Kodak, have a "TV" setting which is just a fast shutter priority.

Like Curt said you might have a bad video input board (common), or the Convergence board might be going bad too (common). At any rate I would ship both to him prior to swapping tubes. just my opinion.


Quote:
Originally Posted by Curt Palme /forum/post/19584372


if the green tube starts pulsing, suspect the A board (RGB input board), if the green is solid in the blue location, then I'd suspect the blue rebuild.

don't you mean B-board?
 

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Discussion Starter · #13 ·
Tried reseating the boards just in case, no luck. What letter boards are involved with the RGB input and convergence?
 

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Discussion Starter · #14 ·
Tube swap results.....

The problem is not in the blue tube posotion. The green tube works fine whithin the blue tube electronics.


EDIT:To clarify one point. I did not swap the deflection yokes or the tube neck assemblies.

CURT YOU WHERE RIGHT FROM THE START!


Bad blue tube.

I have never been happy with the focus on this VDC blue rebuild from the start. This is the second one I have had from VDC. The first one cracked when Ken Whitcombe attempted the first setup before Terry did his.

Now the decision of what to replace the blue tube with.

VDC rebuild again?

New Pany tube from Eiseman?"

Decent used tube from somewhere?


Ideas please!
 

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Quote:
Originally Posted by matrix
New Pany tube from Eiseman?"

Decent used tube from somewhere?


Ideas please!
I don't think VDC even does re-builds anymore? A new tube from Eisemann is your best bet. the 9 inch set I bought from him were very good and i've only heard kudo's to him from people here.
 

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Discussion Starter · #16 ·
I may call it quits on the G70 and go digital. I was switching around with the remote while in service mode and I can trigger an error 39 while switching patterns. I believe the white pattern is doing the trigger even with the brightness and contrast way down. This is with the green tube in the blue tube position. Could be a C block but I doubt it. I have switched the C blocks all the way around. Without pulling the whole thing down and shipping it off to Curt, I really don’t see an economical way of fixing the thing. There are working G70’s on eBay for around $1500. Makes more sense to buy a whole new one and start over or put the money towards the digital DLP. I am getting tired hitting my head onf the beast hanging from the low ceiling in the basement.
 

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Discussion Starter · #17 ·
One more try before I throw the towel in. Are these diagnal lines from a defective deflection yoke or tube or a bad board?

 

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Well it might be crud stuck to the guns grids. Try tapping the tubes neck with something non conductive. G2 short anyone???
 

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Quote:
Originally Posted by matrix /forum/post/19588484


CURT YOU WHERE RIGHT FROM THE START!

Tell my g/f that, would ya?



I don't think rebuilds are available, so that's out. Regardless, I wouldn't get a rebuild. Check with Greg or VDC about new P16 tubes, not sure who carries what right now.


I am working on a completely different source, and hope to have something in place in the new year for many/all tubes.
 

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Discussion Starter · #20 ·
Curt, thanks for the chime in. I just put the thing back together in spite of the diagonal lines. The blue tube is blooming and will not respond to "RASTER OFF" on the remote. The red and green will respond but the blue remains lit without the video image. Very bright! Does this give a clue?
 
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