Sony 1270Q shutdown - AVS Forum
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post #1 of 6 Old 02-11-2013, 06:11 PM - Thread Starter
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I recently brought my old Sony VPH-1270Q out of storage to use as a basement system. It turned on without issue, and ran for about 10 minutes before it just shut off on its own. I was playing with the convergence crosshatch when it shut off, and there was no indication of a problem. Now it only turns on for about half a second before it clicks off. I'm very experienced with electronic repair, but this one has me stumped for now, and I don't want to spend a ton of time on it. I do have the full service manual.

I've thoroughly checked it over for obvious problems like bad soldering, physical damage, water damage,... I traced the protection signals to the CPU board, and none of them seemed to be active in the brief time it would stay on. I also confirmed that the power supply voltages were present and not too high. I had to look at them with an oscilloscope because it shut off too quickly to take a reading with a volt meter. The HV is coming up just before shutdown.

Since it didn't seem to have an obvious fatal problem, I tried jumpering the power on signal to force it on. It will stay on and everything looks normal (rules out the power supply shutting itself down). All the protection signals at the CPU board are correct, the fans are running, there is HV and deflection, and nothing has blown up. I haven't left it on long enough for the CRTs to warm up yet because I would hate to ruin a good set of CRTs.

Does anyone have any suggestions before I pull the CRTs and wait for a 1271, or 1272 to show up on Craigslist?
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post #2 of 6 Old 02-12-2013, 11:03 AM - Thread Starter
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I decided to try powering it up for longer so I could get a better idea of what's happening. As a safety measure, I turned the screen controls to minimum first. After letting the CRTs warm up, I carefully turned up the screen controls, and I was able to get red and blue rasters. I couldn't get any green, but I suspect that's just because the CRTs are biased fully off (200v on the cathodes). The raster is blank with retrace lines, flickering at about 40 Hz, and with heavy keystone distortion, but I suspect that's because the convergence and geometry controls aren't operating. Holding the power on button caused the raster to jump slightly, but there was no sign of OSD.

I'm starting to think the problem is related to the system control circuit since I can't find any reason it should be going into protection shutdown.
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post #3 of 6 Old 02-12-2013, 12:24 PM
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You/'re sort of on your own on this one., mainly because the problem is a bit unusual, and there's no test LEDs or error display like there is on the later units. I would have done exactly what you've done, check the shutdown lines to the CPU. Are you sure the 'status' button is 'on'? If not, it will wipe out all onscreen displays..

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post #4 of 6 Old 02-12-2013, 01:12 PM
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gotta respect folks who have not only the ability but the willpower to repair one of these but gotta wonder if it's worth it. Early 90's ES focusing set = kind loud, kinda blurry, kinda dim.
Keep an eye out on CL and Videogon for something local in the "intermediate " category with EM focus

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post #5 of 6 Old 02-12-2013, 01:48 PM
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BTW Andy, where are you located? Just got a call from an ISF calibrator that he's giving me a 1271 and 1272. One of them is 'supposedly' near new (whatever that means, low hours I guess), and both work. I don't really want either of them, but I'll take them for parts. If you're within driving range of me, you're welcome to the higher hour one for a case of coolers, we could haggle over the 'low hour' one if it truly is mint...smile.gif

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post #6 of 6 Old 02-12-2013, 03:52 PM - Thread Starter
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Believe me, I don't want to put much time, or money into it since it's not the world's best projector. Since it was already there, and I still have the hush box I made for it 10 years ago I figured I might as well set it up for old time's sake. It really didn't look that bad with an 85" curved screen, although it's been 7 years since I've used it, so my memory might be faulty. Blu-Ray didn't even exist, and there wasn't much HD content available where I lived.

Curt,

I'd take a high hour 1271, or 1272 since I could reuse the low hour CRTs from my 1270, but I'm in Austin Texas. I'll just have to keep an eye out for something on Craigslist. There's a G70 for $300 near me. Even if that's a good buy, I'm not sure I want to invest that much into this project. What's a fair price for one (assuming the CRTs are good)?

I will post back with any results I get on the repair. It's so frustrating that it was working fine, then just died for no apparent reason.

Thanks,

Andy
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