#61
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My order from Just Radios came in! Full speed ahead. I placed the order last Monday night the 26th. Great service. Just less than a week to get here.
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#62
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Last edited by Crist Rigott; 12-03-2016 at 03:20 PM. |
#63
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That really is a labor of love.
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#64
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Recapping continues. I replaced the 1.5K 10W Candohm resistor with a 1.5K 50W chassis mount resistor. I was going to use a 25W resistor but the 50W was less than a buck more and I feel it will work better to dissipate the heat.
I'm using 1W resistors to replace the 1/2W carbon composition ones. I'm staying with replacing 1W with 1W and so on. In one instance, I used a 3W resistor instead of a 2W. When I replace a component, I check it off my list, and then highlight it on the schematic. Helps keeps track of what was replaced and a "visual" of my progress. I'm also checking each removed resistor for its value and the value of its replacement. If interested, I'll publish that list when done. Last edited by Crist Rigott; 12-03-2016 at 03:18 PM. |
#65
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I think I found out why I lost HV on the power up. Looks like R82 a 6.8K resistor is open. I'm redoing V16 a 6BQ6GT Horizontal Output tube. This resistor was buried way down.
The resistor has a couple of small cracks on one end. Other than that the resistor looks normal. Last edited by Crist Rigott; 12-03-2016 at 03:15 PM. |
Audiokarma |
#66
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Well, I got V15 and V16 done. It was a bit tight! I like the way Admiral did the 3 resistors on V15!
Here are some before and after pictures. |
#67
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Looks like VK won't allow me to upload any more pictures. I'll have to contact the Admin.
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#68
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I decided to power it up again to check my progress so far. The good news is that it powered up nicely and my B+ is 244 volts. Sams lists 238 volts. I also have a raster and each control seems to do something. Like Brightness does control the brightness and so on. I only have a low level buzz coming through the speaker which can be varied with the volume control. Also no video.
I tried wiggling each tube but that didn't help. On a few like the sound IF amp it clicked pretty loud in the speaker. Seeing I haven't gotten to the IF stages yet, I'm not surprised. What's left to do is the 3 IF stages, Video Detector, a little in the Video Amp, Sound IF amp, Ratio Detector, Sync Amp-Sync Separator, and the Sync Clipper. Once these are done then I'll have to get into the troubleshooting phase. So far so good. Last edited by Crist Rigott; 10-07-2016 at 04:48 PM. |
#69
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I recapped the Video Amp, Sync Amp-Sync Sep., and Sync Clipper. I powered it up and still no audio except some hash which goes to a loud buzz when I touch the center wiper on the volume pot. Basically the same thing as before. I'm thinking that the trouble lies in the IF stages or tuner.
BTW, the tuner inserts have numbers on them that seem to correspond to channel numbers. Does the ones with "4F" on them equal channel 4? I need to know so I can be sure I'm on channel 4 because my CD player and RF modulator are set to Channel 4. Another thing, I remember seeing something about hooking up a CD player directly to the video section? thus bypassing the tuner. Can this be done? Recapping that's left are the 3 IF stages, Sound IF Amp, and the Ratio Detector. Thanks. |
#70
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If you have a source with separate audio and video (not RF) output, you can temporarily connect that video source to the video input of your TV. Typically, this is a spot directly after the video detector, where it sends the video signal to the grid of the video amplifier tube. This diagram is for a different TV, but it should give you the general idea:
http://antiqueradio.org/art/A-V_Adap...oInjection.jpg If the picture looks dramatically better when you inject the video, that suggests that you have a problem somewhere upstream of the injection point, in the tuner/IF/detector stages. Phil Nelson Phil's Old Radios http://antiqueradio.org/index.html |
Audiokarma |
#71
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Phil,
Thanks! I made the box and used alligator clips. I pulled the cap off the volume pot and clipped on the audio. Then I had a spare 6AU6 tube so I bent #1 pin up and soldered on a small extension. I inserted the tube and clipped on the video. I have both audio and video now. I'll trouble shoot the IF stages now. Last edited by Crist Rigott; 10-07-2016 at 05:53 PM. |
#72
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I have a question about my problem. It is either in the IF stages or the tuner. Is there a way to substitute the tuner? That way I could really narrow down the problem.
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#73
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I'd look at the IF stages first. Tuners are comparatively bulletproof in my (limited) experience. Make sure the tuner tubes are good and its contacts are clean.
Yes, there are ways to substitute for the tuner. Back in the day, they sold "tuner subbers," little gizmos that do what they sound like. You can also inject an IF signal (and do many other tricks) with a BK 1077 TV Analyst like this one: http://antiqueradio.org/BK1077BTelevisionAnalyst.htm You can also make simpler measurements such as checking the gain of each stage, checking voltages on each tube, etc. If you have a voltage chart, that's one easy way to start. Phil Nelson Phil's Old Radios http://antiqueradio.org/index.html |
#74
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Phil,
Thanks for the suggestions. I forgot about the voltage chart. I'll do the resistance checks first then the voltage checks. |
#75
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Success! I did the resistance checks per the chart in Sams and found V5 pins 5 and 6 showed open when they should have had 2.6K to pin 8 of the LV rectifier tube (120V). I checked the schematic and R29, a 1K resistor, was between the tube pins and 120V bus. I then did a visual on the resistor and it looked good. I then bumped it with my finger and a lead pulled out of the resistor! I replaced the resistor and now I have very good audio and video through the antenna terminals.
I have to finish replacing the rest of the resistors and a few micas yet. But getting a good picture and sound is very encouraging. BTW, the CRT, a 14CP4 tested very low on my BK 467 but played in my AMC TV came up real good with a very good life test when I gave it to my friend who has a Beltron. He rejuvenated the CRT for me. Last edited by Crist Rigott; 10-07-2016 at 10:56 PM. |
Audiokarma |
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