CurtPalme.com Home Theater Forum

[Curt Palme]

I rarely get stumped with CRTs, but this one has me going.

It started innocently enough. Customer called, local installation from 10 years ago (not mine). Has a DWIN 700 w/a line doubler, and it needed converging. Customer said that the convergence would drift. OK, fine, I took along a motherboard in case the convergence amps were drifting.

For those not familiar with the DWIN, it's a really simple set. Data only, P16 Toshiba ES tubes, super nice image, a la Barco Cine 7 or similar. Almost totally silent. Construction is simple as well. A CPU board is like a Marquee CLM, has the memory and menus on it, controls the whole set, and all of the drive signals start at the CPU board. THe motherboard has the convergence, deflection and a bit of video stuff on it. THe video output boards are similar to the Marquees, with the video output amps on them. THe LVPS also contains the HVPS, all in one box. Various interconnects via Molex cables.

Trip 1- I get to the customer's place and take the covers off. the DWIN cover comes off in 2 pieces, the lens part and the chassis part (again, similar to marquee). Each lid is held in with screws. I take the lens cover off first, the main cover drops on me as SOMEONE (not me!) didn't put the damn screws into the cover when they replaced it. I turn the set on. I see their problem- the image shakes at random in an H direction. Vertical is completely rock solid. it's an intermittent shake, but is there almost all the time. To boot, the raster shifts L-R on top of a shake, so the static convergence is all over the map. I change the motherboard. No difference. Motherboard is held in with 4 screws originally, 8/32 bolts. I find that two screws are actually wood screws. Effing technician!

I change the motherboard. No difference. Shaking still there. sh*t! It must be the CPU board. Dammit!. OK, I take the motherboard back out, take out the CPU board and for good measure I take the power supply as well. Short of the G2 block, the HV splitter, the HV leads and the CRT video amps, I've now got the whole set with me.

I get home, put the boards into my test set here. Solid as a rock. I bang on it, I shake the set, rock solid. NO shaking.

Trip 2 (today). I return with my whole DWIN 700 just in case his set still acts up. Sure enough, I put all his stuff back into his set, shaking is back. Disconnect the inputs, the set shakes by itself. Now, I notice that when the green raster shifts left, the red shifts right. That's a bit strange since the yoke connections for the deflection are seriesed as they are on many projectors. The convergence yokes are of course separated.

So.. thinking maybe I missed something, I put in my motherboard, CPU board and power supply independently. Still shaking. I scratch my head, and decide to change the video amps and HV splitter/G2 block as a whole unit, since wires are soldered together. Still shaking.

In desperation, I disconnect the tube CRT sockets one at a time, and take a yoke out of my projector and let the yoke hang off the one disconnected tube. Still shaking. Yokes are OK.

More desperation, I change the CPU, power supply and motherboard again. More shaking.

So literally the only thing I haven't changed in the set is the wiring harness between the LVPS and the motherboard, and two belly fans are tied into that wiring harness.

I even disconnected the CRT anode leads per tube to see if the shaking stops. Nope.

Trip 3 will be to pull the set down with a friend. Trip 4 will be to return the damn set.

Ideas? Outside interference? Basement installation in a modern style house. No reason for outside interference. No reason for issues with their incoming AC. Pix size itself is rock solid indicating no HV arcing or changing in regulation. Oh, and I disconnected the IR sensor board as well as the video inut Molex connector right at the motherboard. Still shaking.

The only silver lining in the afternoon is that there was a really nice Sansui 9090DB and a Sony Super Beta high end machine waiting for me at the recyclers/.

[Curt Palme]

I rarely get stumped with CRTs, but this one has me going.

It started innocently enough. Customer called, local installation from 10 years ago (not mine). Has a DWIN 700 w/a line doubler, and it needed converging. Customer said that the convergence would drift. OK, fine, I took along a motherboard in case the convergence amps were drifting.

For those not familiar with the DWIN, it's a really simple set. Data only, P16 Toshiba ES tubes, super nice image, a la Barco Cine 7 or similar. Almost totally silent. Construction is simple as well. A CPU board is like a Marquee CLM, has the memory and menus on it, controls the whole set, and all of the drive signals start at the CPU board. THe motherboard has the convergence, deflection and a bit of video stuff on it. THe video output boards are similar to the Marquees, with the video output amps on them. THe LVPS also contains the HVPS, all in one box. Various interconnects via Molex cables.

Trip 1- I get to the customer's place and take the covers off. the DWIN cover comes off in 2 pieces, the lens part and the chassis part (again, similar to marquee). Each lid is held in with screws. I take the lens cover off first, the main cover drops on me as SOMEONE (not me!) didn't put the damn screws into the cover when they replaced it. I turn the set on. I see their problem- the image shakes at random in an H direction. Vertical is completely rock solid. it's an intermittent shake, but is there almost all the time. To boot, the raster shifts L-R on top of a shake, so the static convergence is all over the map. I change the motherboard. No difference. Motherboard is held in with 4 screws originally, 8/32 bolts. I find that two screws are actually wood screws. Effing technician!

I change the motherboard. No difference. Shaking still there. sh*t! It must be the CPU board. Dammit!. OK, I take the motherboard back out, take out the CPU board and for good measure I take the power supply as well. Short of the G2 block, the HV splitter, the HV leads and the CRT video amps, I've now got the whole set with me.

I get home, put the boards into my test set here. Solid as a rock. I bang on it, I shake the set, rock solid. NO shaking.

Trip 2 (today). I return with my whole DWIN 700 just in case his set still acts up. Sure enough, I put all his stuff back into his set, shaking is back. Disconnect the inputs, the set shakes by itself. Now, I notice that when the green raster shifts left, the red shifts right. That's a bit strange since the yoke connections for the deflection are seriesed as they are on many projectors. The convergence yokes are of course separated.

So.. thinking maybe I missed something, I put in my motherboard, CPU board and power supply independently. Still shaking. I scratch my head, and decide to change the video amps and HV splitter/G2 block as a whole unit, since wires are soldered together. Still shaking.

In desperation, I disconnect the tube CRT sockets one at a time, and take a yoke out of my projector and let the yoke hang off the one disconnected tube. Still shaking. Yokes are OK.

More desperation, I change the CPU, power supply and motherboard again. More shaking.

So literally the only thing I haven't changed in the set is the wiring harness between the LVPS and the motherboard, and two belly fans are tied into that wiring harness.

I even disconnected the CRT anode leads per tube to see if the shaking stops. Nope.

Trip 3 will be to pull the set down with a friend. Trip 4 will be to return the damn set.

Ideas? Outside interference? Basement installation in a modern style house. No reason for outside interference. No reason for issues with their incoming AC. Pix size itself is rock solid indicating no HV arcing or changing in regulation. Oh, and I disconnected the IR sensor board as well as the video inut Molex connector right at the motherboard. Still shaking.

The only silver lining in the afternoon is that there was a really nice Sansui 9090DB and a Sony Super Beta high end machine waiting for me at the recyclers/.

[mp20748]

On the Dwin, all of the video circuits are on each neck board. So rule the video stages out, especially with the convergence grids moving in opposite directions.

And with the indication of the grids moving in opposite direction horizontally, I would suspect the problem to be a distant to close varying magnetic field. Horizontal sweep is basically tied together on these sets, therefore the only way to have the grids move opposite, it would have to be a magnetic force that's only effecting the horizontal sweep. plus I've had this problem before, but not on a Dwin.

[Curt Palme]

Yup, that's the conclusion I came to as well. I can't see an intermittent belly fan cause this, but that's the one thing I thought about 1/2 way home today. I should have cut the fan wires before I left.

I will power the set up on the floor before I leave at his place to make sure that something wasn't installed above the projector that could affect it. It's a mystery until I go back...

[Curt Palme]

Yup, that's the conclusion I came to as well. I can't see an intermittent belly fan cause this, but that's the one thing I thought about 1/2 way home today. I should have cut the fan wires before I left.

I will power the set up on the floor before I leave at his place to make sure that something wasn't installed above the projector that could affect it. It's a mystery until I go back...

[mp20748]

We had this problem on a Barco 909 in a military facility. It took a while to isolate. It was on a three projector blend setup, and the problem only showed up on the right projector (left screen). At first I thought the problem was vibration that effected only the right projector. We purchased a small lazer pointer and attached it to the projector pointed at the screen to see if the problem was from vibration.

After noticing that not all grids moved the same, we then suspected something magnetic that was closer top to the right projector. We had the building engineer called in to look at what's in the ceiling and ducts. to later look into adjoining rooms, to later end up on the floor below the rooms that where the projectors were installed.

When going to the floor below following the building engineer, he opened a door to a large room where there was a lot of noise and a bunch of large machines that looked like generators. Not sure what that was in the room, but I did learn to that if I had simply purchased a compass, I would have solve the problem a long time ago.

[Curt Palme]

Just an FYI from the customer when I asked him if something was added in the house:

Nothing new. When the projector warms up it does get better. Worse when cold. The room is solid concrete all around. Walls are 12 inch and roof is 10 inch solid concrete. I haven't added anything new. It seems like the sound from the subs also distorts it. You can see it move as bass is on.

[Curt Palme]

Just an FYI from the customer when I asked him if something was added in the house:

Nothing new. When the projector warms up it does get better. Worse when cold. The room is solid concrete all around. Walls are 12 inch and roof is 10 inch solid concrete. I haven't added anything new. It seems like the sound from the subs also distorts it. You can see it move as bass is on.

[Tim in Phoenix]

[stefuel]

Swap out the wiring harness from a known working projector.
Just get it done before the Bruins win tonight. I wouldn't want a disgruntled tech working on my projector

[CasetheCorvetteman]

How much steel is in that concrete? What are the chances it may have a voltage induced into the steel reinforcing from some electrical installation??

If there is an electrical installation passing that projector that is carrying a reasonable amount of current, it may be generating enough magnetic field to cause issues.

I have seen this at work where we had issues with CRT displays in about 40 poker machines. Incomming mains run in a cable tray on the underside of the concrete slab, which is quite thick. Probably about 1 foot thick. From there, the poker machines sit on a console that is around 600mm tall, then the height of the machine its self, so in total, the magnetic flux was traveling around about 6 or 7 feet. Even that far away, 30-40 amps was all it took.

The effect was wavy lines, MAJOR wavy lines ( abit like hitting the degause button on a computer monitor, but continuous ), rolling picture, substantial jittering side to side on almost all the effected machines, and all those machines performed perfectly when moved out of the interference.

Take your compass, and also one of those induction type test pens if youve got one.

[garyfritz]

If you bought your 700 with you, did you try turning it on to see if it suffered from the same / similar problem? Especially if you could hoist it up close to the customer's 700? That would seem to definitely determine if it's the projector or the environment.

[Curt Palme]

I'll do that when I return with my buddy in the next couple of days. It's a really nice house, and I didn't want to risk nicking the stairwell wall trying to cart the 700 down by myself.

[Curt Palme]

I'll do that when I return with my buddy in the next couple of days. It's a really nice house, and I didn't want to risk nicking the stairwell wall trying to cart the 700 down by myself.

[garyfritz]

Jeeze Curt, you're used to slinging around G90s and 909s. I would think you could pop that itty-bitty thing in your pocket.

Wrap a couple of straps around it and you can carry it like a suitcase. Hell I hauled my 8500 up & down stairs like that, with lenses, though not carrying it suitcase fashion!!

[Curt Palme]

Do you REALLY want me to post pix of my wall going into the shop? Repainted it last year, I gotta get the drywall mud out..

[Curt Palme]

Do you REALLY want me to post pix of my wall going into the shop? Repainted it last year, I gotta get the drywall mud out..

[VideoGrabber]

Curt, I agree with Mike.

[VideoGrabber]

[Curt Palme]

BTW, from now on EVERYTHING comes into the shop for service. I say that almost every time I go out to repair a CRT. It's always something other than what I think it is. Very strange, since my batting average is super high on email tech support stuff.

Generally speaking, I hate doing service calls when I try and repair something in the field. Setups and alignment, no problems, I'm always prepared for that, but service calls in the field SUCK.

[Curt Palme]

BTW, from now on EVERYTHING comes into the shop for service. I say that almost every time I go out to repair a CRT. It's always something other than what I think it is. Very strange, since my batting average is super high on email tech support stuff.

Generally speaking, I hate doing service calls when I try and repair something in the field. Setups and alignment, no problems, I'm always prepared for that, but service calls in the field SUCK.

[Gannon]

Yeah, turns us into digital beings.

Either heroes or zeroes.



AND, that f'in' MURPHY is always lingering about, with frequency and severity of his effectiveness directly proportional to the distance from your shop.

[Gannon]

Multiplied by the distance to the nearest Radio Shack, to the power of the distance to the nearest REAL parts emporium.


Goes to mere certainty when they have an event the next day.

[VideoGrabber]

So, Curt, whatever happened with this? Or have you not been back there yet?

[Curt Palme]

Haven't been back yet. That hopefully will happen today. Rest assured, this will not go unfinished!

[Curt Palme]

Haven't been back yet. That hopefully will happen today. Rest assured, this will not go unfinished!

[stefuel]