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Old 01-08-2019, 12:26 AM
Jeff Jeff is offline
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Join Date: Oct 2015
Posts: 32
Question Issue with GE "Portacolor III"

This set's been a real thorn in my side, so I posted to the classifieds looking for a set to swap parts with, and it turns out there were actually a lot of sets that used the same chassis, only problem is they are apparently unobtanium. Anyways, my scope is saying I'm not getting any video out of the IF amp ic, (nte1545) but I've replaced it twice, and still no signal. It's got the classic "clean" raster (no snow) symptom of a bad detector, and when I inject composite video into the first video amp, there's no black and white video, just color. I suspect this is because composite is 1v peak to peak and the amp expects 2v. I've ordered another replacement IF amp chip, as the other two were old stock. I'm a little perplexed at this point, as I don't see how two IF amp chips were bad, although they were from the same seller.

Attached is a pic of this section of the schematic. The little numbers scribbled on the chip are voltage readings I took, and you probably can't read them as the file size was reduced, but the only thing of note was that pin 3 was supposed to be .7v, but is 4.5v, and I can't figure out why.
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File Type: jpg circuitdiagram.jpg (112.9 KB, 50 views)
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