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blue_z
Joined: 27 Apr 2006
Posts: 63
Location: So Calif
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| Posted: Tue Jun 04, 2013 4:41 am Post subject: DWIN HD-700 issues: blue level and losing sync |
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I have been trying to setup the DWIN HD700 that I got from Curt and jkruger about 6 weeks ago.
But there's one major and one minor issue that needs solving.
1. blue level is too high
The entire raster area of the blue tube is dimly lit up, as if Brightness just for blue is turned up. Blue Gain and Blue Level in the Greyscale menu can still be adjusted, but not enough to remove the blue tinge to the viewed image.
This problem has occurred three times. It seems to happen whenever I "disturbed" the blue CRT, i.e. pull out the tube or unplug/plug the HV cables right next to it. On two occasions, I've unknowingly done something to undo this elevated blue level. The second time this blue level got "corrected", I do remember that I was adjusting the yoke on the blue CRT and after finishing tightening the clamp, I noticed that the blue level was back to normal. The DWIN was able to operate in a normal manner for a few days until I had to "disturb" the blue CRT again. So now that this blue level has gone bonkers a 3rd time a few days ago, this time nothing seems to restore it to a normal level.
This elevated blue level persists:
. even after a power cycle (including unplugging from mains);
. when Brightness, Blue Level and Blue Level are all set to minimum (0);
. after cables are jiggled and connections are broken and remade;
Could this be a tube issue or a bad neck board or ???
2. 1280x960 input loses sync when warmed up
I'm using an HTPC with a nVidia GeForce 210 GPU as the video source for the DWIN HD700 projector. The preferred desktop resolution is 1280x960, which has a 4:3 aspect ratio but widescreen 1280x720 can easily be letterboxed. With reduced horizontal porches (based on advice long ago from MarkW), this is about a 60KHz horz scanrate; the HD700 is rated for up to 65KHz.
I can setup this DWIN HD700 to accept and display a 1280x960 resolution for 32-bit color. But as the PJ warms up, the projected image slowly shifts to the left side of the screen. After about 30 minutes the left edge of the image is folding upon itself. After about 45 minutes the image is totally unstable and it looks like that there are about 5 copies of the video frame stacked vertically.
But I can call up a menu or built-in test pattern and that is stable. I can switch to another (lower) resolution at the HTPC (like 1024x768 or 720p) and the image is stable. But once the DWIN is warmed up, it will not display a stable image from a 1280x960 video input. The PJ has otherwise operated okay at lower resolutions for 4 hours.
Is this fixable? Or is the HD700 simply not capable of this 1280x960 resolution?
This PJ has just over 3200 hours, and is about 9 years old.
Any ideas to resolve these issues?
Thanks in advance!
Regards
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the big E
Joined: 20 Apr 2013
Posts: 1928
Location: speedwell Tn.
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| Posted: Tue Jun 04, 2013 5:54 am Post subject: |
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Not sure about the sync issue but I would check the neck board as it could have worked loose (I had this issue with my Ecp not long after I got only to find out the blue tube neck board had worked loose in transit(mine did a bright blue flash and shut down the hv cage because of it the first time afterward I could tap the top of the set to reduce the blue tube from overpowering the image I checked the neck board and pushed it back on the tube fully and haven't had a issue since)
If the neck board isn't loose it may be going bad
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crt king of black
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blue_z
Joined: 27 Apr 2006
Posts: 63
Location: So Calif
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| Posted: Tue Jun 04, 2013 6:04 am Post subject: |
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Thanks for the suggestion, but the neck board is seated okay.
Actually I have to remove it from the tube when I pull the CRT (and lens) out of the chassis.
So the neck boards(s) have been off & on the tubes a few times.
I've even cleaned the tube pins.
Regards
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the big E
Joined: 20 Apr 2013
Posts: 1928
Location: speedwell Tn.
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| Posted: Tue Jun 04, 2013 6:07 am Post subject: |
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| blue_z wrote: | Thanks for the suggestion, but the neck board is seated okay.
Actually I have to remove it from the tube when I pull the CRT out of the chassis.
So the neck boards(s) have been off & on the tubes a few times.
I've even cleaned the tube pins.
Regards |
Neck board could be failing(I recently replaced the neck boards on a samsung rptv after the convergence amp board took out the red tube)
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Tue Jun 04, 2013 12:59 pm Post subject: |
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The neck board could be bad, but I'd suspect one of the connectors carrying the video signal has a bad connection. This includes the large white connector at the very back of the motherboard that brings the signal from the BNC connectors at the front.
It could also be a bad blue tube, changing in emission. Rare but possible.
Sync issue-no idea, but frankly you're out of the sweet spot. I'd suspect something on the motherboard or CPU board. You could pull them and send them up for repair, but frankly, why not just run at a resolution that works consistently?
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Tim in Phoenix
Joined: 21 Oct 2006
Posts: 4409
Location: Phoenix
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| Posted: Tue Jun 04, 2013 1:16 pm Post subject: |
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Hello
Maybe try reflowing the solder connections on the neckboard.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Jun 04, 2013 1:21 pm Post subject: |
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The G2 pot on the neckboard may be dirty. With the projector off, swipe it back and forth a dozen or more times. Then start it up and reset it for no raster.
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blue_z
Joined: 27 Apr 2006
Posts: 63
Location: So Calif
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| Posted: Tue Jun 04, 2013 8:37 pm Post subject: |
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Thanks for the ideas so far.
| Curt Palme wrote: | | The neck board could be bad, but I'd suspect one of the connectors carrying the video signal has a bad connection. This includes the large white connector at the very back of the motherboard that brings the signal from the BNC connectors at the front. |
Trying the simplest first, I disconnected the blue input at the front panel (I had already tried different VGA-5BNC cables): blue tube still lit up.
Disconnected the Molex connector for RGBHV at the motherboard: blue tube still lit up.
Tentative conclusion: early input connection doesn't affect blue level issue.
| the big E wrote: | | Neck board could be failing(I recently replaced the neck boards on a samsung rptv after the convergence amp board took out the red tube) |
| Curt Palme wrote: | | The neck board could be bad, ... |
| macgyver655 wrote: | | The G2 pot on the neckboard may be dirty. With the projector off, swipe it back and forth a dozen or more times. Then start it up and reset it for no raster. |
So there's three votes for the neck board.
Since I don't have another blue board to swap with, I decide to try macgyver655's pot idea.
The mounting of the potentiometer is a kludge, and an indication of DWIN was too cheap to re-layout the board in spite of finding mistakes (e.g. the PCB fiberglass is scored to ensure that some adjacent traces that are too close to each other aren't shorted). The neckboards are laid out so that the dial of the pot would face downward, away from the technician. So DWIN rotates the pot 180 degrees so that the dial is accessible, and wraps the the middle lead over the edge of the PCB to make the connection to its solder pad.
But on my blue neckboard this pot is wobbly. The pots on the green and red boards seem rigid, well connected to the PCB. Initially I don't see or can determine why this pot is not as secure as the others. But before I'm done reinstalling the neckboard on the end of the tube, I touch the pot and then notice it can now move more than it should. Really close inspection indicates that there's a clean break on the #3 lead as it enters the pot body. Not sure if I actually broke the lead. The history of this PJ indicates that is has been serviced more than once by DWIN, and there's obvious signs of rework on this neckboard.
Don't know if I can/should replace this pot myself.
Maybe a replacement blue neckboard from Curt is a better solution?
Would matching resistances between pins 1&2 and 2&3 from the old pot to the new pot be sufficient to get the proper G2 voltage for the blue tube on my PJ?
Regards
Last edited by blue_z on Tue Jun 04, 2013 8:45 pm; edited 1 time in total
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the big E
Joined: 20 Apr 2013
Posts: 1928
Location: speedwell Tn.
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| Posted: Tue Jun 04, 2013 8:43 pm Post subject: |
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| blue_z wrote: | Thanks for the ideas so far.
| Curt Palme wrote: | | The neck board could be bad, but I'd suspect one of the connectors carrying the video signal has a bad connection. This includes the large white connector at the very back of the motherboard that brings the signal from the BNC connectors at the front. |
Trying the simplest first, I disconnected the blue input at the front panel (I had already tried different VGA-5BNC cables): blue tube still lit up.
Disconnected the Molex connector for RGBHV at the motherboard: blue tube still lit up.
Tentative conclusion: early input connection doesn't affect blue level issue.
| the big E wrote: | | Neck board could be failing(I recently replaced the neck boards on a samsung rptv after the convergence amp board took out the red tube) |
| Curt Palme wrote: | | The neck board could be bad, ... |
| macgyver655 wrote: | | The G2 pot on the neckboard may be dirty. With the projector off, swipe it back and forth a dozen or more times. Then start it up and reset it for no raster. |
So there's three votes for the neck board.
Since I don't have another blue board to swap with, I decide to try macgyver655's pot idea.
The mounting of the potentiometer is a kludge, and an indication of DWIN was too cheap to re-layout the board in spite of finding mistakes (e.g. the PCB fiberglass is scored to ensure that some adjacent traces that are too close to each other aren't shorted). The neckboards are laid out so that the dial of the pot would face downward, away from the technician. So DWIN rotates the pot 180 degrees so that the dial is accessible, and wraps the the middle lead over the edge of the PCB to make the connection to its solder pad.
But on my blue neckboard this pot is wobbly. The pots on the green and red boards seem rigid, well connected to the PCB. Initially I don't see or can determine why this pot is not as secure as the others. But before I'm done reinstalling the neckboard on the end of the tube, I touch the pot and then notice it can now move more than it should. Really close inspection indicates that there's a clean break on the #3 lead as it enters the pot body. Not sure if I actually broke the lead. The history of this PJ indicates that is has been serviced more than once by DWIN, and there's obvious signs of rework on this neckboard.
Don't know if I can/should replace this pot myself.
Maybe a replacement blue neckboard from Curt is a better solution?
Would a matching resistance between pins 1 & 2 from the pot be sufficient to get the proper G2 voltage for the blue tube on my PJ?
Regards |
I would just replace the neck board given its history and not fool with the pot on the board as the g2 voltage is risky busness to work with if not careful and can do major damage to the set if you make a mistake while tring to repair the current neck board(the only guy I would let work on the board if it was mine would be curt)
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Jun 04, 2013 9:59 pm Post subject: |
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I will refrain from any further response and let Curt continue.
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Wed Jun 05, 2013 12:13 am Post subject: |
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BTW, electronics never 'is failing'. It either works or it doesn't. 
'It's failing' can only really mean a bad connection. What I would do is measure the G2 voltage coming off the wiper of the blue G2 pot, and see if it jumps around. The only 'failure' I've had on a DWIN CRT socket are a couple of parts that will kill the tube video output completely. My guess is that the fluctuating brightness is indeed related to the G2 voltage level, which will change the brightness level no question.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Wed Jun 05, 2013 12:27 am Post subject: |
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| Curt Palme wrote: | BTW, electronics never 'is failing'. It either works or it doesn't.
'It's failing' can only really mean a bad connection. What I would do is measure the G2 voltage coming off the wiper of the blue G2 pot, and see if it jumps around. The only 'failure' I've had on a DWIN CRT socket are a couple of parts that will kill the tube video output completely. My guess is that the fluctuating brightness is indeed related to the G2 voltage level, which will change the brightness level no question. |
Hey, quit speed reading when it's important. LOL. "I touch the pot and then notice it can now move more than it should. Really close inspection indicates that there's a clean break on the #3 lead as it enters the pot body. Not sure if I actually broke the lead."
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Wed Jun 05, 2013 12:28 am Post subject: |
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I dropped out of the conversation in case you want to do the repair or sell him another neck board.
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the big E
Joined: 20 Apr 2013
Posts: 1928
Location: speedwell Tn.
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| Posted: Wed Jun 05, 2013 12:30 am Post subject: |
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Curt electronics can fail I had a hp computer that died not long after I got it and it was brand new(hp claimed it was fixed it wasn't)
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blue_z
Joined: 27 Apr 2006
Posts: 63
Location: So Calif
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| Posted: Wed Jun 05, 2013 1:28 am Post subject: |
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| Curt Palme wrote: | | BTW, electronics never 'is failing'. It either works or it doesn't. |
I've been working with digital electronics for several decades, and seen intermittent "failures" before the hardware/system had a hard failure. I.E. a long time ago I was programming a digital plotter, and about once a session at random a couple of feet of paper would feed through the plotter. I couldn't correlate the plotter misbehavior to any commands I was sending to it, so I warned the boss that there's an intermittent HW or firmware error in the plotter. He poo-poos that assessment, but a week later I come to work and there's a plotter repair guy fixing it 'cause it spits out paper continuously when turned on. Vindication!
| Quote: | | 'It's failing' can only really mean a bad connection. What I would do is measure the G2 voltage coming off the wiper of the blue G2 pot, and see if it jumps around. The only 'failure' I've had on a DWIN CRT socket are a couple of parts that will kill the tube video output completely. My guess is that the fluctuating brightness is indeed related to the G2 voltage level, which will change the brightness level no question. |
Is it safe to use this board to measure the voltage?
It's pin 3 of the pot that is now not connected to the ground side. So the pot is now just a (small?) voltage drop instead of a proper voltage divider?
The blue level wasn't "jumping around" or "fluctuating". It was either normal or too bright (at a steady level) for extended periods.
What range is the G2 voltage? I have meters that only measure up to 600VDC, and the highest voltage I've probed has been about 500V in a tube audio amp.
Regards
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the big E
Joined: 20 Apr 2013
Posts: 1928
Location: speedwell Tn.
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| Posted: Wed Jun 05, 2013 1:32 am Post subject: |
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| blue_z wrote: | | Curt Palme wrote: | | BTW, electronics never 'is failing'. It either works or it doesn't. |
I've been working with digital electronics for several decades, and seen intermittent "failures" before the hardware/system had a hard failure. I.E. a long time ago I was programming a digital plotter, and about once a session at random a couple of feet of paper would feed through the plotter. I couldn't correlate the plotter misbehavior to any commands I was sending to it, so I warned the boss that there's an intermittent HW or firmware error in the plotter. He poo-poos that assessment, but a week later I come to work and there's a plotter repair guy fixing it 'cause it spits out paper continuously when turned on. Vindication!
| Quote: | | 'It's failing' can only really mean a bad connection. What I would do is measure the G2 voltage coming off the wiper of the blue G2 pot, and see if it jumps around. The only 'failure' I've had on a DWIN CRT socket are a couple of parts that will kill the tube video output completely. My guess is that the fluctuating brightness is indeed related to the G2 voltage level, which will change the brightness level no question. |
Is it safe to use this board to measure the voltage?
It's pin 3 of the pot that is now not connected to the ground side. So the pot is now just a (small?) voltage drop instead of a proper voltage divider?
The blue level wasn't "jumping around" or "fluctuating". It was either normal or too bright (at a steady level) for extended periods.
What range is the G2 voltage? I have meters that only measure up to 600VDC, and the highest voltage I've probed has been about 500V in a tube audio amp.
Regards |
I have had computers turn themselves on when no one was there but I am not continuing from here on
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blue_z
Joined: 27 Apr 2006
Posts: 63
Location: So Calif
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| Posted: Fri Jun 14, 2013 8:04 pm Post subject: |
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Thanks to the hints, the DWIN now has a normal blue level.
The G2 pot on the neckboard had a fractured lead as it exited the body, so it was replaced. The original part has been end-of-lifed, so it was substituted with an equivalent Vishay M63X205 trimmer resistor.
The original part, with the center lead wrapping around the board edge and extension wire tack soldered to the lead:
The repair, with the three leads bent to accommodate the PCB error:
Regards
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the big E
Joined: 20 Apr 2013
Posts: 1928
Location: speedwell Tn.
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| Posted: Fri Jun 14, 2013 8:08 pm Post subject: |
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| blue_z wrote: | Thanks to the hints, the DWIN now has a normal blue level.
The G2 pot on the neckboard had a fractured lead as it exited the body, so it was replaced. The original part has been end-of-lifed, so it was substituted with an equivalent Vishay M63X205 trimmer resistor.
The original part, with the center lead wrapping around the board edge and extension wire tack soldered to the lead:
The repair, with the three leads bent to accommodate the PCB error:
Regards |
Glad to hear you got it fixed
I have been tinkering around on my nec 10pg(needs new caps and a possible part on the video output board) and my Ecp has a high voltage leak in the power supply(yet hasn't died from it)
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