Help, please

[DevJust]

Hello everyone. I am new to the board. I was referred here by someone at DIY message board for an answer to my problem. Any help would be tremendous.

I sure hope someone may know what I am talking about. I have a 35 inch RCA TV that is about 7-8 years old. (I don't know what the model is off the top of my head) I am having big problems with it and none of it makes any sense. With the cable, all the stations are clear but all but one has static for sound. And one even has a radio station coming in for the sound. OK the odd thing is that I have a splitter from the main cable out of the wall and the other TV works fine, all the channels with sound. So I thought maybe I had a bad cable so I unhooked the main cable and went directly to the bad tv. Still the same. But, video games and DVDs play good. What could the problem be? Sorry if the story is hard to follow or even if this is the wrong place to post this. I am just at my wits end.

[JPKNHTP]

-JPKNHTP

[jimandy]

DevJust, You've troubleshot it well and one final step may be academic, but interesting. If you're in range of some broadcast staions, unhook the cable altogether and attach a rabbit ear temporarily. If the problem persists it is confirmed the TV is the problem.

[Robert Reed]

As Jimandy suggested, try rabbet ears or outside antenna ,but make sure you progam TV for AIR channels. If still bad, you probably have internal problems in the sound I.F. strip or a bad crystal in conversion oscillator. If you are up to speed on repair, you will definately need a schematic to go any further.

[rshayes]

You have a fair amount of information. Since you have good video, the tuner and video IF strip are probably OK. The game and DVD work. If they use either a component video (RCA plug) or S-video (DIN plug) connection to the TV set, the sound is going through separate cables (usually RCA plugs or miniature stereo plugs) directly to the audio stages and not through the tuner and IF strip.

The first place to look would be in the sound IF stages, the sound detector, and the switching that brings the TV sound to the audio stages.

[jwax]

Sounds like a lame approach, but have the cable company check your signal levels. The sig level may be borderline for the big RCA. They don't want radio stations coming down the cable!

[JerryR]

DevJust, RCA TVs of that vintage that had the tunner integrated on the main board were a major source of weired problems, some of the problems just did not look like it's a tunner/IF problem. resoldering all connections in the tunner/IF(remove the shields) assembly usually fixed it.
HTH
JerryR

[jollyrgr]

I have another possibility; the type of cable system the tuner is set to. If I recall there are Low-High VHF, Midband, Superband, Hyperband, and Ultraband channel sets. Each of these bands could be STANDARD, HRC, or ICC. On the HRC and ICC system the video and audio carriers are offset and this would explain the lack of audio and the weird radio station on one channel. (It might be that your set is configured for STANDARD and your cable system is HRC or ICC or it could be that your cable system is STANDARD but your set is configured for HRC or ICC.)

My first suggestion would be to rescan the channel lineup but force the set to scan for ANTENNA signals first as others suggested. (If you don't have any local channels, scan for an RF modulator from a VCR.) If the "Over The Air" signals work fine, then try scanning the cable system signal using the ANTENNA setting and NOT the CATV setting. In other words look for OTA signals but have the cable TV coax hooked up. If you get pictures on channels 2-13 but wrong/no sound it is likely you have a non-standard cable system. If this is the case you may manually have to change the standard within the cable tuner setup. Then try scanning the cable signal using the various modes of cable systems.

As I stated earlier there are several bands of cable systems and these DO NOT correspond to the UHF channels found OTA. In addition to the different bands there are "STANDARD", "HRC", and "ICC" systems. The HRC system is a Harmonically Related Carrier and ICC (or sometimes IRC) is Incrementally Coherent Related Carrier. The audio and video carriers on these two systems are PURPOSELY shifted around to prevent co-channel interference. It might be that the cable system uses one of these two schemes and you manually have to tell the set to look for this signal. (On the other sets it might be automatic.) Or it might be that you are on HRC or ICC/IRC and the system is standard.

The selection for the HRC and ICC may be a small switch on the front panel of the set (hidden under a panel) or possibly on the back of the set near where the coax enters. Or it might be a menu setting within the on screen displays. (Edd, can you help me on where this is at on RCA sets from 7 or 8 years ago?)

[haklesup]

FM radio is stuffed between channels 6 and 7, if you are getting FM audio from these channels, it indicates a problem with the tuner.

8 years is not bad for a TV though replacing a 35"er is not going to be cheap in any technology. It sounds like it still makes a fine monitor using the AV inputs. If nothing else, you can still use it with a VCR tuner or cable box. Either would be cheaper than a repair shop. You wouldn't be the first.

If you're dedicated to fixing it, look for a cold solder joint to a coil inside one of the shielded areas on the PCB. The cold solder joint may not be to the PCB but where the terminals and fine wires of the coil connect, at least thats where I found a similar problem with my sony (thanks E W)

[DevJust]

Thanks to all of you for your time in trying to help. I must admit though, it was like trying to read Russian to me seeing that I am no where near capable of doing most of that stuff. LOL. I guess working on electronics and working on bulldozers don't go hand and hand.

I did have a thought. My wife and I have been debating about going to a satalite network for some time now. I was just wondering if the dish system has a different hook up to the tv ( for example. RCA plugs ) and that may solve the problem short term. At least until we may be in better shape to replace a 35 inch TV set.

[jimandy]

Do you have a VCR around the house, one designed to record off air and cable channels? If you do then you could try attaching your cable service to the VCR and patch the VCR into your TV via those RCA jacks (one for audio and one for video) - this assumes your TV has those inputs, often referred at as AV inputs. Then you can select your channels with the VCR

[DevJust]

All is well for now. Running the cable through the vcr down to the tv with the rca plugs works like a charm. Thank all you guys for the help.