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Post by tschaeikaei on Apr 1, 2016 21:07:25 GMT -5
Grounding looks good, congratulations
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Post by tschaeikaei on Mar 24, 2016 11:38:55 GMT -5
The paint is to prevent the aluminum from corroding. And it will corrode very heavily if it is exposed to the (monoetylene)glycol. But since you used propyleneglycol, could be that nothing will happen. Why do you ask after filling? I would leave it as is now and give it a try. Regards, Julian
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Post by tschaeikaei on Mar 23, 2016 17:37:10 GMT -5
So why don't you use the 7800h red with the new green and blue? So you save the new red for future use. If you're using the 7800h red together with a new green and blue and use a red filtered c-element, i could imagine they'll all wear equally fast. That's kind of what i would want and expect. But i think your real problem at this point is that you don't have spare housings, right? I would not think a new tube is better than a rebuild, the sim grades are rebuild, too. And i think Eisemann gets them from Lexel, but i'm not sure. Do you mean arcing inside the blue tube? Contamination means dirty glycol? Since you opened another thread on nearly the same topic, where you ask if it would make sense to use a blue sim grade. Why should a finer focus blue tube (that's what sim grade means, right?) be of any use. You'll defocuss the blue anyways. And you're not gonna see that on the screen. So if you are making the focus worse on purpose, why would you spend lots of money for a finer focus blue. Don't get me wrong, i did not use sim grades myself, but i cannot think of any advantage on blue. Neither of red as my red tubes always were a bit sharper then the green of the same projector and the green tube determines the overall focus. That's why it is in the middle (no flapping needed) and why people spend so much time on tweaking the green. I think the reason the red tubes being sharper is that they're driven with lower current and this causes less spotsize and less gaussian blur (electron beam hitting the phosphor). Regards, Julian
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Post by tschaeikaei on Mar 23, 2016 16:23:38 GMT -5
I don't get the point why you want to change that red tube. If phosphor and emission are good, why would you change it? The "3 new out of the box" is a RGB set? G and or B in the projector are worn? I'd cut the worn tubes (regardless of color) out of their housings and silicone into the housings whatever tube you need. But I don't think that rebuild is in any case worse than original panasonic. Would you mind telling the whole story? I still don't get why you want to stop using a good tube. Regards, Julian
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Post by tschaeikaei on Mar 23, 2016 16:12:15 GMT -5
According to wikipedia, propylene glycol has a refractive index of 1,4324 whereas MONO- etylene glycol has 1,4318. This is so close together that i think it should be possible using propylene glycol instead of monoetyleneglycol (which is the standard stuff) and mix it with glycerine (1,4745) maybe in a different ratio than the standard 70/30. Plus 1,2 propandiol (=propylene glycol) is a approved food additive and (i found no proof for this) most likely it isn't corrosive like monoetylene glycol. So if it is clear like water... i'd try it. I actually have about 500ml of propylene glycol here. It is clear, defenitely. But i haven't compared it to other stuff, just a quick look. Regards, Julian
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Post by tschaeikaei on Mar 23, 2016 15:21:02 GMT -5
Afaik (and I've done some research and spoke to different people) a rebuild tube uses a new phosphor coating (and aluminum backing), and a new electron gun, which is most likely the high rez- gun if you're rebuilding tubes today. And of course the aquadag (conductive anode coating) is also new. So everything that is kept is the glass and maybe the outer carbon conductive coating. So in my opinion it is actually better to have a rebuild tube than a NOS one. You'll get state of the art electron gun systems and a new (maybe better quality) phosphor coating. What should be the advantage using a NOS vs. a rebuild? The production process is also exactly the same. Regards, Julian
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Post by tschaeikaei on Feb 16, 2016 18:13:17 GMT -5
I must have had a false reading on the meter because they were still in the circuit when i measured them the first time. After Gjaky asked me again about them i desoldered one pin of each resistor and got an infinite resistance reading. Too bad, sometimes i feel like a real idiot It was the first i measured (after seeing R1001 blown) and noted them "ok" on my checklist. I reassembled the projector and everything seems fine. Going on with the setup tomorrow. Could i still get an answer on how fast Q20 has to switch? I like the idea of replacing it with another mosfet with less Rds on to be sure it doesn't blow again. Regards, Julian
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Post by tschaeikaei on Feb 16, 2016 14:06:34 GMT -5
Skip the math, i found some resistors. The board is fully working again. But still the 3V is not as i think it should be. +3.7 and -4.1V at the worst case. mod-supply ramps to aobut -120V if the picture is 100% wide. I'm going to reassemble everything now.
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Post by tschaeikaei on Feb 16, 2016 13:03:21 GMT -5
Do you have actual pictures of the mirror and how it is attached to the projector? I'm very interested in this, really nice idea. Regards, Julian
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Post by tschaeikaei on Feb 16, 2016 12:25:37 GMT -5
Mastertech, do you mean center convergence on red?
I tried that on both red and blue in all directions yesterday. Worked well, but i did not tweak it to the limit, meaning 0 or 100% of the range.
In the service manual i found that R93 and R96 are both 1/3W 1Ohm. R1001 is 2.2Ohm and the same size so i think it is 1/3W, too.
Am i right there is the full 85V (or maybe a bit reduced under load) flowing through Q20 and the resistors?
So assuming Q20 with an Rdson of 1 Ohm (datasheet tells this) 0.41Ohms 1W of the 3 parallel resistors in series with 0.47Ohms 1W of R97, L2 being in the 0.1Ohms range... Regards, Julian
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Post by tschaeikaei on Feb 16, 2016 12:16:00 GMT -5
Ha! 100 points for Mr. Gjaky! Both of them open connection. Although they look like new out of the box. This is really annoying because that part of the circuit was the first i checked. I don't have 1 Ohm resistors here, could you tell me if i could use a fuse instead and what value it should have? I will replace R93, R96 and R1001 all together with it. Those 0.41 Ohms should not matter to much, should it? Thank you, Regards, Julian
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Post by tschaeikaei on Feb 16, 2016 11:48:15 GMT -5
Oh yes, you are right. It does follow but not to the very end of the page. I have to scroll one step up again. Knowing that it makes things easier, didn't notice before. Thank you. So no need to change anything i'll live with that. Regards, Julian
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Post by tschaeikaei on Feb 16, 2016 11:41:30 GMT -5
Hey, would it be possible to add the site navigation that is currently at the top of the pages only also to the bottom of pages? I mean the site navigation first, second, third.... page of a thread. Would make navigation easier because you usually are at the bottom of a page before you go to the next one. Thanks! Regards, Julian
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Post by tschaeikaei on Feb 16, 2016 11:18:08 GMT -5
Ok, i did solder some wires onto the board and measured the voltages. Percentage values stand for PIC-2 width settings +3V measured at C40: 3.4V 0-100% -3V at C39: -3.68V at 0%, falling to -4V at 100% mod-supply: -80V at 0%, linear falling to -102V at 66%, 97V at 100% ground for all measurements between C39 and C40
Regards, Julian
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Post by tschaeikaei on Feb 15, 2016 19:00:36 GMT -5
Thank you Gabor. I don't understand at all what U2 is doing, but i'm going to follow your instructions and change it. I still had the old Q20 laying around and tested it again. 32Ohms between source and drain in either direction, no continuity from gate to one of the other pins. Even checked with the lab power supply, 35V from gate to the other two pins... no current flow in any direction. Do you agree with me that U12 has to be on the safe side? Oh and could you tell me what frequency does Q20 switch? I saw this thing has a Rds on of 1 Ohm, what lead me to the guess that i should use another MOSFET with smaller resistance here. Should improve temperature problems. cdn-reichelt.de/documents/datenblatt/A100/IRF730_FSC.pdfIRF 730 is the same part as MTP5N40 as it is called in my schematic. I'm going to test the board again in the projector now after i did change U2 and made sure everything discrete around is ok. Will report back in a few minutes. Thanks! Julian No, still the same.
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