Mr. Mentor,
Thanx for your reply. No, I did not test the receiver on separate OTA signals, although I have an AB switch and antenna in the attic. The symptoms I saw were enough to convince me the problem was
1) video processor or, 2) combination of failures, either of which would be excessively expensive and time consuming for me to repair.
Regarding: "In general, chips pretty much work, or don't. It's rare to get the sort of fault that you're describing from any kind of semiconductor failure. My money would be on caps."
While I generally agree with this above rationale, if the semiconductor or IC naturally runs hot or very hot, there can be situations where the heat sink compound has dried out and the solder is getting so hot as to make intermittent electrical contact with the PC board or wiring. In such a case, applying fresh heat sink compound, re-mounting the component and sucking up the old solder from the pins and re-soldering with fresh solder connections can lead to a return of reliable operation. I've had experience with this very same situation where the output IC was electrically just fine, but it was getting too hot not being adequately heat sunk. Result was cold solder connections to the PC board due to repeated excessive heating then later cooling.
Have you tested your Sony on VHF reception vs. UHF reception? Are the symptoms the same with either band? What happens if you feed the set video from a DVD drive or alternate source, is the video then fine or still distorted? By doing these things, you can end up eliminating a great deal of the circuitry involved in the set. This also tends to isolate what areas could be of concern. The slick part of this is you can do this without removing a single screw.
My reasoning, I have a little Sony KV-1380R sitting right in front of me. This set a few years ago started losing UHF reception which ended up resulting in the 'snow' type display. The first thing I did is move over to VHF to see if the same symptoms existed with intermittent lose of video reception - it didn't. I then fed it a signal from an old VHS recorder. In fact, I used the tuner in the VHS recorder - again, all was well and reliable since it used either channel 3 or 4 (VHF). This pointed to the UHF tuner before I removed one screw from the cabinet. Sure enough, one of the multi-pins extruding from the metal enclosed UHF tuner through the main PC board had become electrically disconnected with heat. Kind of looked like a volcano with a smaller lead sticking up through the middle of the volcano. Under magnification, you could see the black ring around the lead sticking through. I took my thumb nail and nudged the lead and it freely moved. I sucked up the old solder, re-soldered that pin, cleaned up the residual flux, re-assembled the set and it's been working fine for 7 years now on VHF or UHF.
Cheers, Mr. Mentor
| > Bob Swinney | >
| | In general, chips pretty much work, or don't. It's rare to get the sort of | fault that you're describing from any kind of semiconductor failure. My | money would be on caps. | | Arfa | |