I measured 1.1V so it looks like a bad IC. I used the coax tuner chassis box as a ground point. The CRT metal band as a ground gave a lower .8V measurement so I don't think it is a good ground for this test.
Another reply suggested that I check Horizontal Output Transistor. Do you think that is worth looking into at this point? I don't know what to measure for or the designation of the Horizontal Output Transistor. If you feel that the odds are high that IC561is the problem then thats were I will stop.
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Re: I measured 1.1V at pin 2 on IC561
Check for +15V from the flyback pin # 9, if that voltage is present; check R541 and D531. If these parts are good you should find +12V at TP98 nearby C539.
If still not voltage found, I would suggest to desolder and isolate IC561 pin 2.
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Your problem is not in the tuner. Since you have a sound but horizontal line only and when you bump the unit the video comes out, this is only indicated that you have a dry joints in the vertical section.
Re-soldering the cold solder on that area will cure the problem. Dry joints is hard to spot so you need to work with a good source of light. Vertical IC is located near the FBT and secured with the heat sink.
Hope it may help you.
Have a nice day.
Thanks for using fixya.
Your TVs vertical output section has the fault. You just open your TV after disconnecting it from the AC mains wall socket, and locate the vertical output section. This section uses an Ic marked as part [IC 401] on the board and its number is LA7840. Just look for any loose soderings around its components legs, and the solderings at the IC legs, which has 7 of them. The IC stated above will be screwed onto a heatsink to radiate heat out of it when it works.
If all soldering point are fine, come towards the IC legs and measure the voltages at each leg. The voltages must be
pin 1= Ground
pin 2= 12.6
pin 3= 24.7
pin 4= 4.4
pin 5= 4.4
pin 6= 24v [vcc]
pin 7= 1.8
All voltages stated above are DC voltages with respect to ground. If any of this voltage is missing, find out the reason for that. If all of them are noted abnormal, IC may be defective, and replace it.
[vcc] stands for main input voltage to the IC.
If you need any more assistance, feel free to contact me through Fixya. Ok.
Tuner is lokely the cause or cable box that is hooked up is on mute.
If you have no cable box or sat system the cause would be a bad tuner at coaxe region there is ashort in the connection the brings the adio filtered from the tuner to the control IC AMp witch is part of the tuner assay what this means is bad tuner or bad control ic at coaxe region. Or its one of the causes above a device is on mute. Best of luck to you in your repairs. good feedback and ratings will be expected further in this diagnosis.
The chassis series used in that set was notorious for bad solder connections around its tuner and a few other places. (They used the tuner shield to provide a number of ground connections, and these cracked and went flaky.) These connections would cause a variety of problems including a set that won't turn on.
The fuse is located right near the AC mains cord connections on the board. You will probably find it's good. Not much went wrong on this chassis to blow that fuse unless it was power line troubles or shorted parts on the power supply primary side.
Check for 5 volts at one of the 3 pins on the the remote sensor. If the power is there, you probably have a bad EEPROM IC. Operating parameters and TV settings are stored in that chip, and the bad solder connections I mentioned above can lead to the data getting scrambled and a "dead" set. To repair this, you need to resolder the connections at the tuner shield and a few other locations, then replace the EEPROM.
If you Google "RCA tuner solder problems" or something similar, you should find all kinds of information about where to solder. The replacement EEPROMs are available from MCM (www.mcminone.com) and you order the appropriate IC for the chassis. I'm not home now, but when I get home later I'll check my files for the service bulletin RCA released, and look up the EEPROM you need in case that turns out to be the trouble.
Most TVs today use a "hot-chassis" design and a switch-mode power supply. You should use an isolation transformer when doing any service work on a TV. This helps protect you and your test equipment, and can prevent accidental damage to the TV by grounding parts to the wrong point.
Hot-chassis sets use two different grounds. The power supplies have one ground reference for the primary side (hot ground) and a different point for the secondary (cold ground). The point you pick will depend on what part of the TV you're measuring.
If you are troubleshooting a dead set and working on the primary side of the power supply, use the negative lead of the large electrolytic capacitor you'll find near the AC input connection. There's almost always a bridge rectifier and filter cap (300 to 400 uF range, 180 to 250 volt rating, so physically pretty large) in that area to make the raw DC. That's a guaranteed good hot ground. Sometimes the set will have a labeled hot ground point right on the circuit board for you.
For measurements on the secondary (output) side of the supply, almost any shield can is ground. The tuner cover is a good choice.
in theses set's there should be a board that has a module that the power chord plugs into this module supllies the motherboard and the componants on it. to be honest it would be best to just let a professional replace any defective chips orboards at this point because i believe it is not just one problem but several and without me beibg hands on it would be difficult to narrow it down to just a simple answer.
Picture int disappears leaving snow on screen
Resolder the Xtal in the tuner
No picture - screen is empty. Sound is ok
Check IC101 (BA7630F), if video signal comes to input (pin 1) but not present at output (pin 14) then replace this IC
Intermittent video or snow
Resolder points A, B, C, D in tuner PCB, check cold solder on tuner shield 2-106-349-21
The coax connector you describe is called the F connector and the silver box it is attached to is called the tuner. The original F connector or a replacement F connector can be soldered back into the tuner, but the metal frame of the tuner must be straightened out and the center pin must be delicately reattached too. This is quite an easy job but requires some labor, assuming that nothing was jammed into the tuner when the F connector was out and the coils behind the F connector have not been disturbed. I usually charge about $40 to reattach F connectors but if I have to replace the tuner I charge about $50 because it is a lot less labor to replace the tuner and they can be purchased for about $25.
The GE (actually RCA) 35GT690 uses the CTC187 series chassis. The tuner uses the VHF circuits for cable channels lower then 51 and the UHF circuits for the higher channels. This means that the VHF circuits have stopped working in your set. I usually find that this is caused by a defective U7301 IC in the tuner, the SIP IC labeled CXA1594L. This is a very difficult IC to change and all tuner ground solder joints should be resoldered too, so that should be done by someone with experience in the CTC187 chassis.