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#16
08-07-2006, 09:22 PM
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Ok. First things first I wanted to make sure the chassis isn't "hot" (after a fellow AKer this week spoke of getting "tingled" when his set was plugged in one way, but not when the plug was reversed). So first test was to ohm each side of the plug against the chassis. Guess what! One side of the plug was indeed somewhat shorted to the chassis (500 Ohms). Even with the power switch off. That made tracing it down rather easy. The two black-plastic "line filter" capacitors shown here, one was toast.
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#17
08-07-2006, 09:37 PM
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...so this evening was about cutting out sticky ooey-gooey (probably chewy) wax-paper capacitors and replacing them with Orange Drops. Pictured is 23 of 29 caps replaced. The four big ones remaining are .25mFd@400V which I didn't have in stock -- to be ordered soon, with electrolytic order already planned. Two more wax caps are not plainly in sight in the photo. Looking forward to getting the new Orange Drops, to put the messy job behind me. Mouser.com usually delivers 2nd-day, I'll make the order up probably tomorrow (after I inventory the remaining electrolytics). There are two electolytics in the photo (leftmost, bottomish black one, and topmost, lefmost end-view). I don't have those on hand either (20mFd@150V). Then of course the multi-section cans on top. Those should be an interesting topic, for another day...
The set has an unusual Hi-Voltage cage interlock -- when the cage cover is bolted into place, a sheet-metal tab fits thru a slot in the chassis and rests up against a spring-loaded toggle switch in series with the main power switch. No cabinet-back interlock like we're used to seeing -- I guess Magnavox at the time figured the "low Voltage" side was safe enough. The rest of the chassis is ready to rock, no cheater-cord required. As you can see, I replaced the two "line filter" caps with equivalent orange drops as well. The 500-Ohm short went away -- no more hot chassis! More later. -k
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#18
08-10-2006, 07:27 PM
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Made my capacitor order with www.justradios.com. Mouser.com let me down on selection and on price this time. 4 or 5 days I should have the parts to finish the recap. Maybe work on the cabinet over the weekend... -k
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#19
08-17-2006, 11:41 AM
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Capacitors arrived from www.JustRadios.com in about 6 days. According to the US Post Office:
Electronic Shipping Info Received *, August 10, 2006 Enroute, August 12, 2006, 7:43 pm, ATLANTA, GA 30369 Enroute, August 15, 2006, 12:33 am, ALLEN PARK, MI 48101 Delivered, August 16, 2006, 11:32 am (home) Excellent capacitors. I highly recommend them. Last night I installed the remainder of the orange-drops and three electrolytics, so the underside of the chassis is completely recapped (photo). Replaced one of the topside electrolytic multi-cans, first time I ever tried "re-canning" one with discrete capacitors (keeps an authentic appearance by salvaging the original can). Went very well. I'll photograph the next one in progress. It's probably the most time-consuming part of the whole job. Assuming all else goes straightforwardly.
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#20
08-17-2006, 03:52 PM
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Topside electrolytics C1 (A, B, and C) and C2 (A, B and C) are done. C3 and C4 left to do, then this stage of the task is (finally) done. As viewed from below-chassis (note the perfboard and heat-shrink-tubed wire connections on the lower two circular areas). Details next post.
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#22
08-17-2006, 04:13 PM
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3 discrete capacitors, matching the ratings called for in the specs, are mounted on a small piece of perfboard. A hole is drilled in the center of the perfboard first to allow the ground-side (or "-") wire to exit. The Positive ("+") sides are mounted to the face of the perfboard, the "-" sides are common, soldered together at the top, with a wire coming back down the center and thru the hole in the perfboard. The "+" leads are left long and sticking thru separate and reasonably-spaced perfboard holes. A quick solder at the perfboard foil holds it all in place.
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#23
08-17-2006, 04:20 PM
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Mount the perfboard to the chassis where the original can used to be. This isn't an unpleasant sight as-is, but if you want you can wrap the caps with just enough electrical tape such that the original can fits snugly over the trio and reasonably resembles an original look.
You can glue the perfboard down, drill and screw or rivet it down, or (as I chose in this example) tie it down by passing salvaged clipped capacitor leads thru two perfboard holes and the thru the original tab holes and then "twist-tie"-ing the perfboards down. This seems like the least intrusive method, if somebody wanted to undo my work later.
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#24
08-17-2006, 04:28 PM
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Wire up the capacitors thru the perfboard, as originally wired (shown in-progress). Use plenty of spaghetti tubing and heat-shrink to make sure everything's well-insulated. When taking the old can out, make sure you label all the loose wires (ex: my green post-it tabs).
You can see my "twist-tie" method of mounting the perfboards. It worked well, if not terribly elegant. Two down, two to go. I find this part really tedious, so I'll tackle the other two tomorrow. - k
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#26
09-21-2006, 09:47 PM
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One last way-out-of-tolerance resistor was dragging down the height (R96 of Sams 82-7). Replaced that, lots of height to work with now. Had some retrace lines and bad linearity/centering (the Bones/Justice pic). Set up a mirror and found a balance with the Vert Lin, Height, and Vert Centering controls that gave a pretty linear pic, vertically centered, and minimal retrace lines. Put the glass faceplate temporarily over the pic tube to make sure the height matches the height of the mask (Pepsi truck shot). I like it. I guess it's done.
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#27
09-21-2006, 09:51 PM
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Looks great so far.
 Assuming that this is your current state of affairsyou're almost home. Looks like it needs some work on the vertical output. Possibly just adjusting the vert height and vert linearity (they usually interact with each other). But a weak but passing on the tube tester output tube can cause this. But usually leaky caps (but you replaced them all, yes). High value resistors (above about half a megohm) are known to drift high. so check the resistors in the vertical circuits. As it is, I see that your flyback is healthy, picture tube looks good too. And the deflection yoke looks like it's good too. Those are hard to find replacements for. And the tuner and IF must also be working well enough to at least get a strong TV station, or your VCR. I now see that you got the vertical fixed. good job. 
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#28
09-22-2006, 01:42 AM
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Looking good
John
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#30
09-22-2006, 09:30 PM
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I plan on block-sanding the cabinet top with 600 and finer paper and re-clearcoating it. The original clearcoat is flaked badly and has a few water-rings (and is a little dirty). The sides are fine as-is except the veneer is lifted in places. I'll have to glue it down again. Other than that, it's good.
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