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#31
08-24-2020, 10:22 AM
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If it was rebuilt it's possible the rebuilder only had the older bent guns on hand and used what they had... I've heard of this several times before.
I doubt it had a trap from new but some of the early aluminized types did either due to logistics or cases where the standard type of a tube was non-aluminized but the A postfix version was aluminized.
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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 
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#32
08-24-2020, 12:40 PM
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And it starts!
 I have just ordered a mess of electrolytic capacitors for this set. This sort of adds more fuel to the discussion that popped up in another thread about replace vs reform, I pretty much knew that C1 would fail, but I was gonna try it anyway, because the original had 3 sections in it, and the replacement cap had 4, one that was unused left unhooked, and when I hooked a tester up to it, ( I tried 2 different ones. ) it mesured over 3 times what it should have been... So as I mentioned, I was not surprised when I put power to it and it got uncomfortably warm to the touch after only 15-20 min, not to start the replace vs reform thing going again, but for me at least, after that, there was no way I was going to trust that cap.
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#33
08-24-2020, 01:32 PM
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.....(4) It acts as one plate of a high voltage capacitor. The other plate is the conductive outside paint or “aquadag”. This capacitor filters the high voltage. Which is derived from the horizontal oscillator and has 15 kHz ripple.
I beg to differ. the capacitor that filters the HV is composed of the aquadag coating on the outside of the CRT, the aquadag coating inside of the CRT and the glass between the two aquadags acting as the dielectric. The aluminized coating on the back of the screen is not part of this capacitor.
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#34
08-24-2020, 01:46 PM
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Quote:
https://frank.pocnet.net/sheets/127/2/21AUP4.pdf jr
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#35
08-25-2020, 10:55 PM
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worked on the SC a bit tonight
replaced the multi can caps, and a few papers. https://i.imgur.com/HrEK6JY.jpg admired the really ugly solder work of the person who replaced the cap before me.   then did something rather bold and Shango like, did a slow power up just to see what would happen, YES, I still have a bunch of papers to replace, but I wanted to see anyway. after a slow bring up... no smoke , no fire, had the teltale hiss in the speaker. flipped the phono/TV switch into TV mode to see if HV would come on,.,,, nothing... no surprise, it has been sitting forever. did some checking ,, found NO power at the cap of the HOT, hmmm am i missing a voltage? did some checks, they seem to be all there, what's going on here  check fuse for HV, Ok... voltage at damper OK, out of damper, OK... this is NOT looking good!  power is getting to the FBT, but not the HOT plate cap? pulled out the FBT.. resistance check OK... huh? https://i.imgur.com/bd06HX6.jpg power comes in from damper to FBT on red wire, out to HOT on the yellow... wait a sec, it is there and OK when measured at the lug of the FBT but gone at the HOT? this is something I have not seen before the wire IS connected, but degraded and not carrying power it's all green and krusty... a first for me :p
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#36
08-26-2020, 01:47 PM
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The SAMMs for this set is getting extremely frustrating with its lack of info/ omissions.
Example, the LV power source seems to be just 2 voltages, 290v and 95v, there is a voltage divider off the 290v line noted as “voltage source R” this goes to the 95v line, it has r128 r129 (4.7k) and c5 (10uf) however they are flagged as “not used” in some sets, I have looked, and looked AND LOOKED... their location is not shown anywhere in the pics in this SAMMs folder, I have no idea where they would be if they are in this set, furthermore... if it DOES NOT have that voltage divider (r128-129 c5) then where the hell does the 95v come from? Been looking for hours and can't work it out, the SAMMs must be incomplete,   If you wish to share in this agonizing frustration, you can grab the SAMMs from my FTP and see for yourself! Yes, people still use ftp address = suzaku.us name = videokarma pass = rcavictor100
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#37
08-26-2020, 07:39 PM
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it's alive! sort of!!
https://imgur.com/76iHGNt I saw what I wanted to see. I have a lot of caps to replace!
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#38
08-26-2020, 08:51 PM
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things done so far...
replaced the 2 multican electrolytic caps C1 & C2 https://imgur.com/9cm9vHf C1 replaced a few paper caps in the area. will silicone the caps down next to the x-former once the other caps are replaced. https://imgur.com/H0w6Qs0 C2 Replaced the faulty wire from the FBT to the HOT place cap. there is obvious Vert sweep problems, and the Horz is off freq. will try to work on it a bit each week a bit .
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#39
08-27-2020, 10:58 PM
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This SAMMs is really starting to annoy me,, where the HELL does the 95v come from?
it does not make any sense... does anyone have the riders version for this? perhaps they did not lay it out so stupidly...
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#40
08-28-2020, 12:50 PM
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Looks like they are pulling it from the cathode of the 12BY7 video output tube. They are using that tube as a voltage divider in other words.
I'm look as Riders vol 16. Not sure how it looks in Sams.
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#41
08-28-2020, 04:18 PM
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Quote:
https://imgur.com/YseSmi3 those dots mean voltage mesured from 95v line. https://imgur.com/Ev1QkEu r56 is 1/2 watt, (or so it says ) here om sams, that is a lot of power to be pulling through that resistor for that line esp when the alt version Volt source R, which is not in this set, is seems, uses 2 watt resistors :/ nothing here seems to make any sense... there should be a alt high power source for the 95v but not sure what it it.
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=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために Last edited by Yamamaya42; 08-28-2020 at 04:29 PM.
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#42
08-29-2020, 01:47 AM
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i spent the night replacing a lot of paper caps, 90% were quite bad, after which i was able to get a full screen raster, but still could not tune in anything...
then I remembered  the horrid problems with contacts the drum tuners have, so i opened it and looked... https://imgur.com/ZhqjAHK   black as night. so i scrubbed off chan 3 with an eraser, and. https://imgur.com/Heff2BR  great progress for such a short time! I still got caps to replace, and I'm sure that there are bad resistors in there too. but it's going OK so far.
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#43
08-30-2020, 01:47 AM
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https://imgur.com/fEsFhYK
here it is today tuner is still giving problems. works sometimes then stops this is with direct video input still have vert lin problems will prob have to pull all tubes and scrub pins and sockets. and replace even the caps that were replaced before, and not assume that they are OK even though they are not paper ( film type ) who knows how long they were in there... https://i.imgur.com/HrEK6JY.jpg you can see one of the old replaced caps in the top left. although, it could also be resistors causing the problem.
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#44
08-30-2020, 01:44 PM
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vert linearity looking much better.
https://imgur.com/gcteUfS found bad resistors. https://imgur.com/5c1EP28 r58 r59 way WAY off, they had been replaced before, but are still no good. had 1/2 watt ones in there, put in 1 watts https://imgur.com/jduVGCo REALLY BAD will prob find other very bad resistors too :/
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#45
08-30-2020, 11:52 PM
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All tubes have green krud on the pins like my FADA did, so I'm guessing the sockets are dirty too, rather than trying to clean the RF/ IF tubes, I will just replace them, they are old enough, example, when I removed the 4th IF, this was not easy because the tube shield was rusted on, ALL of them are rusty
, the tube under was an original stromberg carlson tube ( 6cb6 ) though I could not find any trace of that number on the tube, I don't know if it came off, or if was never on or what I'm still debating on taking apart the tuner to try t clean it, the SAMS clearly shows a pic with the drum removed , showing the contacts, but I'm not sure how it comes out, if it comes out w/o much trouble, then it would make easy access to the contacts for cleaning.
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Linear Mode
