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| neo-tec nt3500 38" monitor wont turn on!! |
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| rocklite:
hi i have a monitor that wont turn on anymore. it is a neo-tec nt-3500 afaik. i have been playing with the pots on the chassis pcbs in order to try and make the image better. sometimes when i move certain pots the monitor turns right off and wont start up again until i set them back to where they were. the monitor started to make a lot more noise when displaying brighter colors lately and i have been trying to adjust them again to be quieter. when i went to turn on my cab today it wouldnt start up at all. it seems to be making a ticking sound. "shwoop-tick, shwoop-tick" it goes. and it just does that instead of powering up. my monitor is connected directly to a "peter chou usp-11-200xt" single block power supply. it used to connect with some bare molex pins but i snipped them off to connect to a grounded power cable to a power bar connected to the wall instead. it was just as noisy this way so i decided to connect with the power supply again. i reconnected it to the peter chou by stuffing the threaded cables into the proper places (molex pins removed). it worked fine last time i saw it but today it wont turn on at all. tried plugging into the wall again but it gave me the same result. it sounds like its trying to power up. every second i hear this tick/ click/ bweep noise that just repeats in one second. help. even if you can think of a better place to ask. please help. |
| lilshawn:
sounds like maybe you've overdriven the HOT (horizontal output transistor) by cranking up the B+ too high and caused it to fry. the HOT is a large 3 legged transistor mounted to a heatsink. you can check it dirty and quick with a multimeter by placing one lead on the middle leg and probing on of the two others. a reading of continuity (zero ohms) or low resistance says it's bad. (should read in the Kohms or Mohms) do this with the power off of course. |
| MonMotha:
Oh boy, you really shouldn't go playing with controls on these things when you don't know what they do. It's possible to damage components or even create hazards by defeating protection mechanisms like the x-ray protection. The ticking sound you hear is the power supply attempting to start up, finding that something is shorted and therefore drawing way too much power, then giving up and trying again later. Likely culprits are the HOT or vertical output IC with the HOT probably being more likely given the circumstances. Hopefully nothing else got hurt due to the high B+. It does sound like you've blown up the HOT. It will need to be replaced, if so. Before powering back up, you'll also need to make sure that some of the controls are at least in reasonable positions, especially B+ and any HV/x-ray settings, though HV/x-ray settings are often glued into place at the factory. This may be difficult without some service info, especially if the pots aren't labeled on the board. Hopefully you marked the original position of everything before you started tweaking them? |
| rocklite:
hmm. well there are at least 4 possible ones to test then. i cant reach them all with the multimeter so im going to have to dissconnect the whole chassis board. i disconnected my flyback but i didnt hear a pop. is that a bad sign? |
| lilshawn:
no...most newer chassis have system built into them to discharge most of the voltage after a few moments. you might want to take a wire with an aligator clip at each end and clip one end to the metal frame and stick the other end inside the bellybutton of the tube...it's the tube that has the charge in it, not the electronics. |
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