#31
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Quote:
Flickr its great for posting numerous pictures of a restore and makes sense when you have lots of photos, instead of one-off posts like this, where it is kludgy to use.
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"When resistors increase in value, they're worthless" -Dave G |
#32
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Flickr acts the same on all my devices....VK's upload/image size limits prevent me from uploading %99.8 percent of the pictures I have, and a hosting site has proved easier for me to implement/use than resizing my images and hosting them on VK.
It is a bit less clunky if you run adblock plus in your browser (I still get popups occasionally). My photobucket account is effectively dead to me....Once I (rapidly) ran out of storage capacity and they started prompting me to buy more, I switched to flickr and have not looked back....Well I do occasionally go there to post an old photo still on the bucket.
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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 |
#33
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Call me late to the party, but Dad's (incomplete) Sams for the CTC11 is marked up pretty good. There's this (not in Dad's handwriting) - HOT cherries, check Osc tube filament for 6V. Was half. No corrective action listed.
And plenty about contrast, swapping guns to check CRT, and other non-germane stuff. PF Reporter also had an instance... http://www.americanradiohistory.com/...rch=%226dq5%22 Me, no experience earlier than a CTC12, so no real help beyond that note..
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Brian USN RET (Avionics / Cal) CET- Consumer Repair and Avionics ('88) "Capacitor Cosmetologist since '79" When fuses go to work, they quit! |
#34
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Gotta wonder at this point if either of the windings might have shorted turn(s), dragging down the Q enough to keep the oscillator from starting.
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#35
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All the horizontal circuits were mostly the same, even a 16 is easy to troubleshoot with a CTC-9 schematic if you know what to look for.
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Evolution... |
Audiokarma |
#36
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Ed stopped by. I think we nailed it. He said that the horizontal diodes are leaky. Since they're mounted on the vertical board, I didn't even think of it.....but I had a feeling that it was a garbage in/garbage out situation.
He said to replace them with germanium diodes. Any suggestions?
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"Restoring a tube TV is like going to war. A color one is like a land war in Asia." |
#37
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I've seen standard 1N4007s work fine as horizontal AFC diodes...I'd try those first if you've got em.
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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 |
#38
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Just curious , while the AFC dual diode can definitely cause loss of H sync, how would it being 'leaky' prevent the osc from running?
Not tryin' to be a smart arse, just thinking it could be a fault condition I never ran into before. Last edited by old_coot88; 12-03-2016 at 11:52 PM. |
#39
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The actual AFC diodes are selenium according to SAMS. I don't know what the effect would be if you used a different type of diode. Most notably would be the forward junction voltage: germanium - 0.3V; silicon - 0.7V; selenium - 0.95V. I suspect that leaky AFC diodes might cause the first stage of the 6CG7 to drive the oscillator way off frequency to the point of shutting down the oscillator.
Of all the AFC diodes I replaced, the only problem I observed was lousy AFC operation, never an oscillator shutdown. Last edited by Tom9589; 12-04-2016 at 10:59 AM. |
#40
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Honestly not quite sure, but it's a direction to go in. I spied this on ebay, so I said what the heck, let's do this instead: http://www.ebay.com/itm/262744695681...%3AMEBIDX%3AIT
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"Restoring a tube TV is like going to war. A color one is like a land war in Asia." |
Audiokarma |
#41
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Well, obviously that wasn't it.....but here's where I'm at now.
Traced the issue to PW600. I have both the +275V and the +386V voltages, but I still have no -57V. Board's been recapped. I replaced two of the resistors to no avail. I still have a couple yet to check, but since those are values that I don't stock, I figure I might as well order the disc caps as well just to cover all bases. What voltage should I get? Or, should I even bother with the discs? Ed and I worked on this chassis for at least a couple hours weekend before last. We're both scratching our heads.....
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"Restoring a tube TV is like going to war. A color one is like a land war in Asia." |
#42
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Ok this is going out on a limb, but tube sockets have been failing* while looking otherwise intact on recent repairstry the 6CG7 socket, it may have a conductive dust path underneath. Trace those hold coil wires too. I don't have Sams 550 but the resistance table for all the 6CG7 pins needs to be checked.
*Both CTC16 color demodulator 6GU7 sockets and a 12BY7 in the second set could not be helped with deoxit or new tubes.
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"When resistors increase in value, they're worthless" -Dave G |
#43
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Do you have the 24 v and 260v on the plates of V601? This would show if the tube is drawing current.
Since the -57v is developed by rectification of the horizontal drive pulse, I imagine its absence only means there are no H drive pulses. Do you have an oscilloscope? A quick check around V601 would show if the oscillator is running at all. |
#44
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Working backwards in my mind from over a week ago (been a rough week with my wife coming home from rehab), I remember that the oscillator isn't running at all. We checked and re-checked board traces, tube pin continuity, and grounds.
As I understand it, the +275V and the +386V voltages show that everything going into the board is fine. Once again I'm stymied because there are only so many parts here....
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"Restoring a tube TV is like going to war. A color one is like a land war in Asia." |
#45
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Quote:
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"Restoring a tube TV is like going to war. A color one is like a land war in Asia." |
Audiokarma |
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