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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Goldstar CNR-2994P Tuner problem
The set may need a new tuner module.
-- Jerry G. ===== "Boris" wrote in message om... Hello! I really liked the quality of the some of the posts in this group. So here is the problem: I got (from a sale) a very nice GoldStar CNR-2994P TV. After fixing the power supply problem, which I guess caused the owners to sell it, I am left with a strange tuner problem: poor reception quality for most (may be all) channels. Summary of diagnostics: * Although I am able to receive a few (2) channels very well, the main aired channels in my area are shown with poor quality (unlike on my other TV). The TV is generally of very high quality and I would expect at least to match the other TVs in terms of receiver sensitivity. * DVD and VCR play though the RCA jack is excellent (which brings the problem down to the tuner) * Sound is excellent on all channels * There are two standalone (and looking identical) tuners to support picture-in-picture. Unfortunately, all menus are in Korean language and I still haven't been able to find a translation. So, I am not exactly sure how to test both tuners one by one (or even how to invoke the small picture). * There are 3 power supply voltages on each tuner pins: 5, 12 and 33 volts. They are all a little bit lower, but the biggest difference (from the nominal) is in the 33V, which is 29.5V. This is quite strange since this 33V is produced from 40V coming out of the power supply, which is in reality 50V (the only power supply voltage out of normal range). The raw voltage is higher while the zener voltage 33V is lower (could be a filtering problem)! Both tuners have the same 29.5V instead of 33V. * Due to difficulties with Korean, I haven't been able to fully understand the menus, but the AutoProgram also seems to have a problem: some strong channels are visible but not recorded automatically. Any help with debugging the problem would be appreciated! |
#2
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Tuner problem
Can anyone here advise me how to determine if the tuner is broken (versus
tuner supply voltages or subsequent circuits)? Unfortunately, no schematic! Thanks, Boris "Jerry G." wrote in message ... The set may need a new tuner module. Jerry G. |
#3
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Tuner problem
Not without some more information; make, model, chassis, symptoms...
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#4
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Tuner problem
Well, I thought I have described the problem details well in the first
message of this topic. Basically, relatively poor (still watchable) reception quality (definitely from the RF tuner portion). Model: GoldStar CNR-2994P "BWL" wrote in message ... Not without some more information; make, model, chassis, symptoms... |
#5
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Tuner problem
If you're still getting a watchable pic, then the tuner is at least
functioning; may have low or missing AGC voltage (typically about 8volts at full gain); also may have loose or broken isolation capacitor inside antenna connector(if the TV uses one). Possible weak RF amp inside tuner, but subbing with new tuner is really the only way to test for this |
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