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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Wed Oct 12, 2016 5:37 pm Post subject: |
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| jbltecnicspro wrote: | | Which now brings me to another point... Our screen sucks. No ifs, and's or but's. It's a home-built one using Carl's fabric, but I'm honestly not that impressed. Even at 1.1 gain it hot spots. I was thinking about possibly getting a Da-Lite 84-inch rollup. Does anyone here have any experience with Model-B roll-ups? How's quality? Or should I just get a decent permanent screen? Who makes a decent (and affordable) 84-inch screen? I was also thinking about Silver Ticket 92 inch screens, but that would mean I'd have to do it all over again (ceiling mount and all) - which I'm not super opposed to. I'm learning more and more as I go. |
I would stay away from Silver screens of any kind and if your getting hot-spotting now then it's not 1:1 gain.
Typically CRT works best with 1.3:1 gain and the hot-spotting should be very little in exchange for a higher light output.
| jbltecnicspro wrote: | | I put the three color dot lenses up and now the projector is well-focused. |
the filtering on a G70 is done wit hthe C-elements, so the little dots make no sense. Probably added by a service tech who didn't understand the optics. The only "special" lens used oi nthe G70 was the lenses off a VR machine. look at the machine ID tag on the side, if one says G70VR then use those lenses .
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jbltecnicspro
Joined: 23 Apr 2016
Posts: 512
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| Posted: Thu Oct 13, 2016 2:15 am Post subject: |
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| draganm wrote: | | jbltecnicspro wrote: | | Which now brings me to another point... Our screen sucks. No ifs, and's or but's. It's a home-built one using Carl's fabric, but I'm honestly not that impressed. Even at 1.1 gain it hot spots. I was thinking about possibly getting a Da-Lite 84-inch rollup. Does anyone here have any experience with Model-B roll-ups? How's quality? Or should I just get a decent permanent screen? Who makes a decent (and affordable) 84-inch screen? I was also thinking about Silver Ticket 92 inch screens, but that would mean I'd have to do it all over again (ceiling mount and all) - which I'm not super opposed to. I'm learning more and more as I go. |
I would stay away from Silver screens of any kind and if your getting hot-spotting now then it's not 1:1 gain.
Typically CRT works best with 1.3:1 gain and the hot-spotting should be very little in exchange for a higher light output.
| jbltecnicspro wrote: | | I put the three color dot lenses up and now the projector is well-focused. |
the filtering on a G70 is done wit hthe C-elements, so the little dots make no sense. Probably added by a service tech who didn't understand the optics. The only "special" lens used oi nthe G70 was the lenses off a VR machine. look at the machine ID tag on the side, if one says G70VR then use those lenses . |
Regarding the screen - Silver Ticket is the brand, not the color.  Gain is 1.1 white.
Regarding the lenses... Yeah, I matched the group together and the results are good. Though I think the real reason is that the other lens I was using on red had a bad corner focus adjustment. No idea why but the new one is far better. Green and red now match in thickness on grid patterns (yay!).
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jbltecnicspro
Joined: 23 Apr 2016
Posts: 512
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| Posted: Sat Oct 29, 2016 8:12 pm Post subject: |
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And I'm back with more issues. So the convergence board is now the latest to go. The projectors came with two IC's for a convergence board repair and so I attempted that. However, when I put the board back in the projector it threw an Error 23. I'm 99% sure it's the IC's because right before the "repair" the machine powered on no problem. Swapping in the parts projector's board also resulted in a power-on, but the board is shot, as evidenced by blue being very much out of convergence.
So protop on the IC's - if it doesn't have an alphanumeric code on the back plate (the part that is against the heatsink) then it's not genuine. The replacement IC's was given are clones and are likely out-of-spec, and that's most likely causing my problem. For grins, I pulled the spare board's IC's out and sure enough, they have the alphanumeric code on the back as well. So I'm almost 100% sure that the "new" IC's aren't genuine.
That being said, this is the end of the line for me and the G70. As of right now I've spent about $600 fixing it , and I've had them since May. It's now almost November and I have only watched two movies on it. I probably should have quit when the PA board blew.
So at this point I don't really know what to do. Here's my last "hail Mary" - Does anyone here have a working convergence board they'd send me for shipping? I cannot afford to send these boards to Curt (not even one) to fix. I know I'm not entitled to this, and this is more-or-less a last-ditch effort to keep this thing operating long enough so that I can save and assess where to go from here (most likely a projector purchase from Curt, which in hindsight is what I should have done to begin with).
Thanks. 
I'm not sure about other G70's, but while doing more and more research as I've had problems, I've come to the conclusion that these projectors aren't very reliable anymore. Obviously age will factor into that but the G70 seems to be one of the more problem-riddled late-model CRT projectors.
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gregstv
Joined: 27 Aug 2007
Posts: 628
Location: Australia
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| Posted: Sat Oct 29, 2016 8:22 pm Post subject: |
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Double check your soldering. Also check that a track hasn't cracked from heat when removing the old chips. This would be more likely than did chips.
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jbltecnicspro
Joined: 23 Apr 2016
Posts: 512
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| Posted: Sat Oct 29, 2016 8:52 pm Post subject: |
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Thanks Greg. I'm not really seeing anything that jumps out as suspect to me at the moment. I'll have a closer look with a magnifying glass and a better light source.
Edit: Not seeing any burnt traces or bad solder joints. I can get a decent picture up online tomorrow probably.
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Tue Nov 01, 2016 10:24 pm Post subject: |
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there was a known batch of bad STK chips a few years back on fleabay, either counterfeit or manufacturer rejects fished out of a dumpster.
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jbltecnicspro
Joined: 23 Apr 2016
Posts: 512
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| Posted: Sat Nov 05, 2016 9:52 pm Post subject: |
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Does anyone know where I can legitimately find some genuine ones? I did some quick googling but I didn't come up with much.
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Tue Nov 08, 2016 5:52 pm Post subject: |
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| jbltecnicspro wrote: | | Does anyone know where I can legitimately find some genuine ones? I did some quick googling but I didn't come up with much. |
did you try the classics, Mouser, Digikey, Allied Electronics, etc.?
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jbltecnicspro
Joined: 23 Apr 2016
Posts: 512
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| Posted: Tue Nov 08, 2016 6:21 pm Post subject: |
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| draganm wrote: | | jbltecnicspro wrote: | | Does anyone know where I can legitimately find some genuine ones? I did some quick googling but I didn't come up with much. |
did you try the classics, Mouser, Digikey, Allied Electronics, etc.? |
Yessir - nothing comes up with STK392. Sanyo semiconductors are now ON Semiconductor (or I think that's what it's called?) and that particular IC isn't available at those places.
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gregstv
Joined: 27 Aug 2007
Posts: 628
Location: Australia
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| Posted: Tue Nov 08, 2016 6:29 pm Post subject: |
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Check with Curt. He may have a repaired board.
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