#16
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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 |
#17
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Getting back into it again. Thanks to Dave, I now have a good 21AXP22 in it. My brief glass conversion proved to be easily reversible...The most time-consuming part was patching a hole in the CRT shrowd that appears to have been chewed by mice...I filled that with clear silicone caulk and it is hard to tell it ever had a hole (at least from the outside).
I decided to swap the rectifier tube socket contacts in the 5U4 sockets. They were making poor contact (sometimes the set would power up and not have B+ until one was wiggled) and the heater contacts were getting heat discolored so I swapped the 4 unused contacts on each socket with the 4 used ones and tightened the new ones so they make good contact...It used to be I could barely see the 5U4 heaters glow now they glow properly. Got the new AXP installed yesterday, and finally got to the yoke issues. The yoke cover and the sides had rotted. Approximately 1/4 of the side of the yoke was gone, the bottom half of the side was just hanging by the wires that pass through it. I got a ~2-3 quart plastic paint container from ACE hardware. Below the top ~1/2" of the container the diameter was too small to go around the yoke properly and the yoke sides had to be taller than 1/2" so I sliced strips from the side of the bucket with 'teeth' coming out the bottom of the strips, wrapped the strips around and melted the two strips together to fuse them into a ring that enclosed the remains of the old sides of the yoke. I then bent the teeth under and slipped them into gaps between the windings and structure and glued them in place. I trimmed the new sides to match the height best as I could tell it from the warped remnants, then added the ring the lid snaps to and heat fused it in and cut two notches*. I cut a center hole for the neck out of the old lid then enlarged it at top and bottom to match the original. By then I had ground out the rivets that joined the metal parts of the old cover. *The cover contains two levers that protrude from the side of the yoke below the lid (thus the two notches). Those two levers move two pieces of, presumably, steel in and out of a plastic slide track that rides between the yoke windings and CRT neck as some sort of adjustment. I painted the lid and new sides Lincoln touch up paint black and assembled. The result while not perfect is a heck of a lot better than exposed yoke terminal strip and uninstalled adjustment levers. Up close you can tell it is a repair but at least it is a decent looking/working one. While I was at it last night I also repaired a contact in the yoke. There is a box above it that contains an adjuster and a terminal for a device mounted on the blue lateral that is in series with one of the horizontal yoke leads. The terminal that device plugs into broke on me early in the resto and I was using an alligator clip to get by.The contact was basically the same as a fat pin tube socket heater contact so I robbed one from a junk socket and soldered it in on top of the original contact. The yoke is now good. I was able to do a quick roughing in of the purity adjustment last night. Hopefully in the coming week I'll have it working right.
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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 |
#18
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And here I thought you'd be using some 45rpm records and black electrical tape. I ran into that on a set once...
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#19
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Motoroly CRT Install ind Yoke Recovery
WOW!!! Great job. Using the Ace paint buckets, did you have any issue getting the Lincoln (paint brand?) paint to stick and stay stuck to the plastic?
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#20
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Quote:
About 10 years ago I did something similar on a Zenith that was the 3rd tube TV set I owned...I sliced up the plastic top to a cheap dead VCR and made a really lousy yoke cover stand in...It even had electrical tape...I need to redo that one of these days if I haven't yet. Quote:
It was actually Duplicolor paint; the stuff I use on my 78 Lincoln Mark V...It stuck okay with the caveat that I cut the center hole, painted it then later widened it at the top and bottom...When I widened it the ~1/32" along the cut peeled. It touched up fine though.
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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 |
Audiokarma |
#21
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About three weeks ago I tested the tubes in the color circuits...Nearly all were weak and or shorted so I replaced nearly every color stage tube (took a good bit of searching to find the oddball types it uses, but I had them in stock). That got me the rainbow of off-frequency chroma osc. I soon found the osc. slug was both stuck and cracked...Ugh! I pulled the osc. coil and after some debate began the nerve-wracking process of gently compressing/crushing the coil form by a fraction of it's diameter just above the coil where the slug was stuck...With great finesse I was able to crack the old slug up enough for it to drop out of the form in pieces yet keep the form usable and not damage the coil. A tiny bit of the top of the form chipped off, but it is inconsequential.
I took a larger slug (I plan to hunt up the estimated correct size soon) that was handy and adjusted it for color sync. I have color bars now, the tint does not really get them the right color, but I've got them! DSCN9658 by Tom Carlson, on Flickr Between a vacation and other projects, it has sat since then. I need to try either direct video injection or do an alignment...That pastel pic is with color maxed and fine tuning set for max color level.
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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 |
#22
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With a lot more bench time than I've had in a while due to covid19 lockdowns I finally got back to this.
So far I have replaced some off tolerance resistors in the IF and color stages and managed to coax a decent color picture out of it.... however it don't want to stay good. The color osc is drifty and looses lock occasionally....more frustrating is the tendency of the osc to jump between being locked on the correct phase of color burst and the inverse phase...I can sometimes get it to jump between the two by adjusting horizontal hold... Which is not wonderfully stable either.
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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 |
#23
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Nice progress. I think I would worry about the horizontal sync first - could be messing up the burst gate.
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#24
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Quote:
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Charlie Trahan He who dies with the most toys still dies. |
#25
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Quote:
Yesterday one of my habbits specifically tuning to cartoon Network for test signal with saturated color bit me in the butt...the amazing world of gumball was on and with the chroma osc phase sync issue the orange character and the blue character were taking turns being each others color... Glad I had the sound muted or it would have been a confusing episode.
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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 |
Audiokarma |
#26
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Quote:
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#27
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Here in the midwest, we predominately saw RCA and then Zenith sets. I never had a chance to see a Motorola color until mid 60's. Old people liked them because they had a really smooth picture (no detail)
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#28
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Quote:
John |
#29
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Horizontal hold behavior is intermittent. Sometimes it won't sync worth a damn sometimes okay but control lock range is limited sometimes I can get close to the 30 degrees lock in range Sam's suggests is correct. The hold pot has a VERY broad effect on the frequency compared to other sets (heck it will pull it so far the osc will die on a good portion of one end of the range). Trying the Sam's H osc adjustment procedure that involves grounding the H AFC, putting a .1uf between the H osc coil and ground, locking with the hold, removing the cap, locking with the coil (can't do it it isn't very close to frequency), removing the AFC short and calling it done. All the resistors in the horizontal are good the paper caps have been changed and the 680pF mica was changed... I'm not sure what could be changing the coil lock point.
After doing the sams horizontal osc proceedure I got the horizontal lock good but color lock was barely present/not stable for more than a minute. The picture often has bad ringing on high contrast so I have started my first video IF alignment with my B&K 415..the first 2 injection points went well the adjustment on the first was almost spot on, the second needed touch up but was cooperative, the third that goes through the tuner is not close and getting it there is proving difficult...I may have to dig for a 6BC8 for the tuner. Sam's calls out a 6BC8 but a 6BK7 is what is in there... I'll probably have to dig as there are no BC8 in my boxed/labeled tubes so it will be a bunch of digging into my bins of loose pulls. I when I have more time I'm going to have to rant about how Motorola and Sam's think you should deal with removing the H output tube during alignment... they musta been bribed by ohmite.
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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 |
#30
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Sam's errors
When I had my shop sometimes I used to compare factory service manuals with photofacts. Sometimes they were right on and other times there were errors in the Sams version. I guess sometimes you had to take it for what it's worth, keep in mind a lot of time there were service bulletins that came out after both versions were released, and those had some very good info on them
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