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#226
09-06-2022, 01:58 PM
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You will just have to hunt around, there is no telling, for example, the RCA CTC-16s had a bad habit with faulty R48 (150K) R50 (180K), and a few others, my rca 630ts clone had all bad 39 ohm cathode resistors in the IF, same with the Stromberg Carlson TV I did, 47 ohm as did the Arvin, which also had 47 ohm on the cathodes.
It seemed more than coincidence that they had bad resistors in the same places more or less.
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#227
09-06-2022, 03:11 PM
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Well I went over all resistors on all 3 IF tubes and the only one on 2 was a 1.6k that measured 2k that’s it. Is it likely that a disc to ground may be bad ? I still have a hunch that L6 may have been touched it looks like it was moved looking in the adjustment hole. Do you know how to check a germanium diode get a reading on ohms both ways where one side flashes numbers back and forth. And so again if there is sound then the video rides along so I think I could exclude the tuner.
Last edited by timmy; 09-06-2022 at 03:26 PM.
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#228
09-06-2022, 06:14 PM
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there is a diode check feature on your meter.
http://www.instrumart.com/assets/uei...nix-manual.pdf you have to make sure it is diode mode, not sure what button to press but when in the right mode, a diode symbol should be seen on the display. https://www.youtube.com/watch?v=Rj9WpoaX2Gk how the test is done there should be easy access via pins 2 and 4 at L6. diode mode is the only way to really test it. resistance checks wont tell you anything, in diode check mode, one way should be about .5xx on the meter ( give or take) and the other much higher, as seen in that video.
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#229
09-06-2022, 06:37 PM
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That diode test is for silicon diodes the one in the set is a germanium diode much different in diode mode the germanium diode does nothing no reading either way but different reading in resistance mode they are very sensitive and I have these diodes and compared mine with the one in the set and I have my doubts that it’s bad. I just thought there was a special way to check.
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#230
09-06-2022, 06:42 PM
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Quote:
you should be seeing a voltage difference when you change the leads back and forth.
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#232
09-06-2022, 07:04 PM
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Quote:
If you have a replacement already then try the meter on it, if it does not show a reading, it A) not in the right mode, or B) not able to test diodes for some reason. they test the same way https://www.petervis.com/Radios/maki...iode-test.html just give dif readings.
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#235
09-06-2022, 07:37 PM
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Quote:
 chances are that the Detector is OK in the set. what you may end up doing is NOT trusting the tube tester, and getting a whole NOS set of IF tubes, and perhaps Tuner tubes, but that's just a suggestion.
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#236
09-06-2022, 07:46 PM
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Well I hope the detector is good and I even thought of putting in the old tuner tubes which showed shorts to see what happens and I also tried different IF tubes but still the L6 like I said it looks like it was screwed in and out marks left in the plastic sleeve both top and bottom.
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#237
09-06-2022, 08:29 PM
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Let's hope that;s not the case, cause if any if them were changed, then the level of difficulty to align it is very VERY high, needing very special equipment and skills to get it right. sweep marker generator + oscilloscope and LOTS of time / experience.
https://www.youtube.com/watch?v=fHeWbyFMF8A https://www.youtube.com/watch?v=I1h5zNFvn_U&t=212s NOT easy
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#240
09-07-2022, 08:24 AM
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As mentioned before, it's best that you have a set of known good (NOS) IF tubes, 2, 6EH7s 1 6EJ7, and new tuner tubes.
And it looks like you have the coil/core type tuner vs the rotary switch type, these type have a bad habit of getting dirty contacts (black), making tuning impossible, the best way most have found to clean them was to remove the tuner cover, and clean them with a pencil eraser and solvent like isopropyl alcohol or the like, until the contacts are bright and shiny, making sure not to leave any bits of eraser behind. If the tuner has not been cleaned already, there is a good chance that the contacts in there are all black and dirty and a source of trouble.
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Linear Mode
