#31
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I, like a fool, removed the jumper and installed the resistor. It looked like the jumper was installed by a tech. Didn't look like factory issue. Just remove the resistor, install the jumper and wire, per these instructions. |
#32
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Thanks!
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"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free" |
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[QUOTE=Zenith6S321;3126651]The 25MC30 schematic shows the 1.5K resistor connects to pin 1 and 9 of the 3AT2. The 3AT2 PDF shows that pin 4 is a no connect. So pin 4 could be used as a tie point for connecting the other end of the resistor to the anode lead. The schematic does not show this, so I'm guessing.
Dave Hi Dave, is there any way that you can post something showing this resistor connected to pins 1 and 9. Reason being is that if it shows it there then both ends are interconnected to the cathode. According to the .pdf on the tube, pins 2, 5, 6, & 9 are the same as pin 1. Now the second anode lead does for sure connect to one end of the resistor, but I dare to ask is it at a no connect as a tie point or is it at 1 and 9. There is a big difference that presents obvious concerns. My lack of completely understanding the circuit may lend to this. Sorry to keep going back to this, but what I am reading surely makes me wish that I could see a for sure Zenith reference to this.
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"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free" Last edited by Tubejunke; 02-19-2015 at 04:47 PM. |
#34
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[QUOTE=Tubejunke;3126823]
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Dave Last edited by Zenith6S321; 02-19-2015 at 06:44 PM. |
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OK thanks! This diagram drives home the fact that everyone was right but me. I just wanted to see it in black and white as my Sams's schematic only shows the heater connection. Your schematic clearly shows the corona ring being bonded to pin 1 which is the same as pin 9 where that connection is made on mine with one end of the resistor and the plate cap of the regulator. Makes no difference. So the other end along with the second anode lead are at pin 4 of NC just as we all suspected and as DieselJeep has it.
I didn't get a picture because the initial connector pulled out with the tube clean of solder and somehow I had it stuck in my head that it was on pin 4. Duhhh! GeeZ! When I pulled the assembly apart the split resistor, connector and anode lead fell to the bottom of the cage leaving me with two adjacent open holes. In the name of not looking like a complete idiot; at least I suspected that what I had in mind would have caused some major issues and all of this might have been for nothing. Thanks once again for advice and more helpful information. My 25LC30/U is not going to serve me well in this. I didn't realize that Zenith had that many design changes in only a few years. The set pictured on my folder looks like my set. Maybe next time I will have good news. I thought I could get the HV cage off without removing or pulling back the chassis as I got all but one screw out. That one screw is mid way deep and close to the cabinet. Can't win em' all, but removal of the cage will make the job much easier than trying to work through the cover.
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"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free" |
Audiokarma |
#36
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Is HV actually set to 25kv on these? What is the procedure for setting the efficiency coil?
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#37
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Other than that you operate the set normally and turn the slug slowly and find what is called the "dip" point or the point where the lowest current flows and that's about it. If you are like me, you won't be satisfied with that current as it may still be too high due to some other component causing that condition. I hope this helps. I think you can Google setting the cathode current on a vintage color television" and there is a pretty in depth article on this topic, but it is a bit scattered in nature. If you find it you will see what I mean.
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"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free" Last edited by Tubejunke; 02-20-2015 at 06:49 PM. |
#38
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Try it again with a .47uF cap (any voltage >10 should work). You should get different readings, and they may be lower.... Remember the goal of measuring equipment is to load or disturb the behavior of the circuit under test as little as possible. The meter will have very low DC resistance, but may have higher AC impedance, the cap neutralizes that impedance by giving AC an alternate path to follow.
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Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
#39
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Dave |
#40
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Thanks Dave! That should help a lot.
Anyway, today I got everything reassembled and powered it up. Nothing bad happened, but nothing good either. No HV and only a blue glow in the top portion of the rectifier. I put it on my B&K tester and it is dead as a doornail like the heater is open. Not sure where or why that would have happened. So, now I will hunt another 3AT2. A local supplier here has International Servicemaster brand which I don't want to get. If anyone has a supply of these and needs anything of that style base; I have a box of these type tubes which I have no use for including some pretty expensive sweep tubes. Just throwing it out there.
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"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free" Last edited by Tubejunke; 02-21-2015 at 06:32 PM. |
Audiokarma |
#41
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http://www.ebay.com/itm/NOS-Zenith-S...p2054897.l4275 Zenith branded for true authenticity, and you no longer need to worry about heater juice. Sounds like a good deal to me. (No affiliation with seller.) Last edited by NoPegs; 02-21-2015 at 06:39 PM. |
#42
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Have you ever tried a solid state replacement? My only experience is watching a video by one of our members on YouTube where he tries one and the set absolutely would not operate correctly with that type rectifier in it. He went back to the vacuum tube and all was fine.
I just suspect that the arching that went on in more than one place with my old socket got the best of the tube. Months ago before any of the socket issues developed I put and International Servicemaster in the set and it only lasted a few minutes. The one that I just pulled out and tested bad was used before that and up until the socket issue of late. Hopefully another decent quality tube will take care of things.
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"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free" |
#43
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The voltage withstanding and current handling capability of the S-3AT2 replacement exceeds the specs for the normal 3AT2 (A/B) series. |
#44
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shows they sell 3AT2s for $3.00. Other places are probably similar prices. I usually get two of each tube I order to have a spare and in case one is not so good. Actually, a bad 3AT2 matches the Goodman description of the burnt resistor problem. Dave |
#45
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Never had any problems. Usually on an RCA or one of the clones. |
Audiokarma |
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