Magnavox Color Roundie
 

Well, I must say the mover could not have come at the worst time.. 7am without notice woke up by the mother saying this thing is not coming in the house.. And not to mention it was damaged during shipping.. The whole bottom is particle board and one of the legs failed during shipping.. The mover gave me half my money back... Looks like the whole bottom is just going to have to be replaced with plywood..

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On the upper note, the pic tube came up right away, with blue a little weak, but seems to be climbing:
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Lovely find! Particleboard is a terrible product when used as part of the structure in heavy pieces like this. I have seen heaps of sets with a particleboard cabinet, and with the bottom of the set giving out and buckling around the legs - Definitely not safe for shipping with the legs attached.

Had to remove the whole chassis.. Looks like a cap has exploded entirely.. Probably got struck by lightning, I thought that was a fuse of sorts until I saw reminisce of a film cap.. I did try and power up on a variac, with ohm meter before I work the chassis out and at 60 volts it started to spark, meter was only reading .4 amp.. Has to just disconnect everything, some wires I don't know what goes where.. Have no choice other than to remove everything and then see what can be done with the cabinet.. If I would have left everything in, it would have just falling completely apart and I don't want pic tube to get damaged.. Now don't know where to go with the cabinet.. I'm not an expert at wood work..

Talk about 60 years of nicotine.. Wires are all slimy and the stuff just sticks to your hands and don't want to come off..

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Red is looking better
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Pic Tube = Spirit of 76 rebuilt of sorts
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some epoxy should be able to fix that particle board, would be better to remove it, then put some wax paper down on the floor so the epoxy does not run everywhere. Have some would shaving handy to fill in voids from missing bits.

the slime is typical of magnavox, rubbing alcohol and ebow grease will get it fairly clean.

Pots tend to be noisy, lots of action behind those vert mount boards, easy to short wires out.

RCA clone but for the silly swap of the fly and power trans. Like rca the fly is the weak spot unless already replaced with a better one.

good chance it will work as is, since the safety cap is blown, may as well get it out of there, but the rest of the caps are from an era that was pretty good.

Oops I went ahead and used wood glue, and got it outside with cinder blocks piled on top.. I cut out that interlock cap like I did with the GE, have the chassis on the variac with the HV output tube removed, and the tubes are coming up slightly.. I did 30v at first for 15mins and now at 60 volts..

wood glue is fine, I just prefer thin (30min) epoxy since is can be more of structural element (esp if wood shavings are mixed in). Its a bit messy but works fine. You may need to backup the repair with some 1/4" wood triangles under the leg mounts, do them in all 4 corners of course to keep the height correct, and make them large enough to distribute the load.

I may go over the part that's glued with either a thin piece of wood or a metal flat strap that's rectangular.. And i'll bond that to the area with epoxy for even more support.. I hooked the speaker up to chassis and heard normal fuzz noise.. Tried to tune to a channel but don't hear noise to the sound of the tuner as I change channel.. Bump it up to 120 volts from 100 and heard and saw a pop near the power transformer.. Was drawing around the normal 1.3 amps.. All the filter caps stay cold..

should be more like 3.0 amps, guess is the HV is not working as that draws a lot of power. oh, maybe still no horz out tube installed then the 1.3 makes sence.

Another option would be to take that board to a wood working shop and ask them to make another one just like it out of plywood.

I've thought of that too, but If the original can't be fixed.. I'll do that..

Whats the best solution to remove gunk and tar from the wires and PC boards.. I've been using rubbing alcohol, but I wonder if there is something better to use?

I know spatsbear on youtube puts the whole chassis of his sets in the dishwasher, but I not going to do that seeing how I don't even have a dishwasher..

I've got a station tuned into it now.. So looks like another simple fix.. Tuner is dirty, and the little plastic gears for the fine tuning are popping out, so not sure if I can fine tune a channel in..

Don't remove it. at least until after you have base lined the set to determine the current operating status.

After that, if you want to clean it, rubbing alcohol is good for the slime on the wires, q tips are good for cleaning the pcb. Just remember that the parts are very old so any cleaning has to be done gently, and generally is not needed for the set to operate.

I am amazed your TV's CRT is still as strong as your tester says it is. I saw the date code on the tube, January 1976, so that CRT is probably a replacement. However, I would not expect a 39-year-old CRT to test good on all three guns, unless the TV was used very, very little or else it has been rejuvenated once.

BTW, particleboard cabinets were replacing real wood ones by the mid-'70s, although the trend may have started some time earlier. The stand (actually a modified utility cart) my home entertainment system is on is made of particleboard with some sort of fake woodgrain covering. That doesn't surprise me, as I bought the stand in the mid-'80s; by then just about everything was being constructed of this cheap material, a trend that continues to this day. My desk is made of the same stuff, and it is showing its age (I got it in the early 1990s).

One option is to set it in the driveway and hose it down with the garden hose, and maybe a paint brush and some soap for the PCB. I've hosed down a set before and had it go well. The key is to let it dry thoroughly. Here in the Wisconsin coolness it means waiting like three days to a week, but in the scorching Florida sun (I used to live there so I know) I'd reckon that if you give it 3 hours of even sun exposure on the top of the chassis, flip it and do the same for the bottom, and repeat until thorough inspection finds no moisture it will be fine. Word to the wise before you soak it get pictures of any and all paper labels on the chassis.

You can also put rubbing alcohol (isopropyl alcohol) in a spray bottle and use a paint brush or toothbrush to loosen the dirt. Turn the chassis on its side and work from the top down.

Phil Nelson

I would be extremely careful around those PC boards, as they get brittle with age. I had a Silvertone (RCA CTC12 clone) roundie color TV in the early '70s that worked fairly well, until I tried to replace a tube on the video output panel. The tube socket broke out of the board, :no: ruining the set (I was in no position at the time to repair the board). I've been wary of PC boards ever since.

Making some progress on day one:

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Cleaned the chassis with some electrical contact cleaner the boards look better, but still need to go in with a Qtip..
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Fine tuning gears.. Not sure if that green plastic brook.. It sorta flops around with fine tuning, though it does turn the gears, but not sure if its turning the inside parts...
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The two 'fingers' that slide inside the tuner are broke off and gone.
Maybe somebody with a stash of old tuners could come up with a good slider assembly to donate. (It comes with the gears attached.)

If anyone has an extra slider assy I would be interested..

Here's more progress:

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Betron is liking this pic tube even more so, only at 5volts
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Ive got a bunch of these. If this is what you need I'll mail you one, but i'm not sure what part broken on yours, do these look the same?
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Those outside the box does, but I don't know what it looks like on the inside.. I suppose I could crack open the tuner and see... They mentioned something about fingers that slide inside the tuner...

I just looked and I see the hole where the gear goes in, but nothing behind it.. There is a metal piece thats sorta coiled a little around the shaft, one end going into the tuner and looks to have two other feet that aren't going anywhere, maybe that is suppose to force the gears to make contact?

Is that a Standard-Kollsman tuner?

If you need the FT gear, it is not too hard to find. The fingers OldCoot refers to are on either side on the gear slider assembly, just out from the tuner shaft and click into slots in the tuner sheetmetal.

Standards usually had a 6HB7 tube and were used in GE and Mags, not known for good fringe reception IMAO.

Oak tuners were used in Motorola and some others, also not real good in comparison to Zenith and RCA

Looking at reference photos from my previous GE roundie restore, it looks to have the same thing pretty much

http://i1220.photobucket.com/albums/...V/DSCF3157.jpg

I'm looking at the springy thing with feet that's around the shaft, looks like it's suppose to apply some tension on that plastic gear assy.. Looks like it could have been knocked out of place during shipping, especially seeing the condition of the cabinet.. I'll look more into it Monday when I have more time to look into it

I took out the whole clunker and removed the gear assy, I ended up breaking one the of the teeth, the little gears that are attached on each side and goes through and turns the mechanism is very wobbly, So I think there were issues already with it.. I'm going to need a spare from you.. I'll take a few if you don't mind parting with a few..

I put the clunker back in and powered the chassis up again, and still working fine and still can hear audio coming in from a channel.. First time removing one of these clunkers..

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pm sent

Thanks Paul..

Finally got the cabinet in the house, hooked up pic tube and HV, and was greeted with a pic.. Black bar at the bottom convergence is way off it looks like.. Haven't checked any of the tubes yet.. But I'm getting good results so far..

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I left it running for a while, and the original flyback in it started to smoke.. Screen went dead.. I left the room and started to smell a burning smell... These things smell like burning firewood with an odd stench, I thought the house was on fire..

Waited a while and powered back up, and probed the HV and it goes up to 5000kv before falling.. I removed the HV cover and poked around, there's wax drippings and I felt around the donut and felt a bump on the bottom of it.. I heard Shango on Youtube, chisrtv i think on here, is able to fix these, if so, let me know how much you want and I'll mail it to you... I've also got three Thordason flys for CTC15 which I assume will work in this unit.. Still rather have the original repaired if it's repairable..

Never leave the room with a set on. You want to be able to jump at the power switch if things go noticeably wrong.

I hope you did not kill the fly.

I was probably cooking for a good minute before I realized.. There's no obvious marks on the Donut other than the bump on the bottom which was probably there before... Perhaps maybe it took out a tube instead? Tested the 6BK4C 6BK4B in the HV section and fails grid emissions and the 3CU3 is weak... Does anyone know how to get a hold of shango066 from Youtube?

I just looked at my NOS Thordason Flybacks which are FLY-277.. They call for Magnavox Part numbers 361046-1 and 906152-501.. The Sams photofact lists the Magnavox part #361084-1(B) which calls for Thordason FLY-305 which I don't have.. So unless I either #1 have someone fix this one, or #2 find a Thordason FLY-305 I guess the project would end right now... I called Moyers and they are looking in their warehouses...

yes the 361084 is the magnavox number and i have a fly 305 new in box for the maggie combo i have. if you need the fly why dont you take this combo i have here with the fly for 250.00, it has been for sale but i need the fly with the set but if i didnt have this combo then i wouldnt need the fly. need to downsize here alittle, not much room and besides your chassis is and looks exactly the same as mine, a spare chassis helps and this combo works fine, even the flyback.

Last combo he had almost got parted for space reasons (but another member saved it), and earlier in this thread I seem to recall his mom telling him "this is not going in my house" about that little table/legged console...So I doubt he will take you up on this.

If the HV on your set is good, and the fly in it don't look too cooked then I don't see why you would need a spare flyback. Sure it is nice to have a spare fly, but if you dip the horizontal current, add a 125mA (or other appropriate value for the given design) HO tube cathode fuse, and maybe open the HV cage some (or add a fan) to increase air flow the fly should last for a very long time.

Tom is right.. Thanks..

I did a little more poking around and I'm not sure if the flyback in mine is dead.. It sure doesn't hurt to have a spare.. I measured cathode current and it's suppose to be at 200ma, It doesn't stabilize and is way up past that, even turned the slug in the osc coil, gives me wacky readings between 220ma to well over 300ma, and meter just keeps climbing, flyback was getting warm while doing all this.. I tested the Horz osc tube and it's weak, looks like there has been caps replaced on the sweep board before...

What is the HO tube grid voltage relative to specification? If it is not as negative as it should be by a decent margin then your H osc. is dead or not functioning correctly. I'd order a new osc. tube if the old one is weak. Sometimes a weak tube will work as an osc., but it is at high risk of sudden random failure and when the osc. fails if let run too long damage to the HO tube and or fly usually result.

I'm getting -72 DC volts at pin 7.. Sams calls for -120.. Someone must have replaced or removed the Horz osc, one or two of the solder pads have been burnt off and jumpered from the horz osc..

Good luck, I hope the fly is good. The tuner gears are in the mail.

Thanks Paul..

I've just tested of the resistors on the sweep board.. There are alot of them that are way out of spec.. Not sure if it's because they are still in the circuit... Flyback area still has that burnt wood smell, smells like wood that was burnt and wet afterwords, sorta like a wet burnt smell I wanna say.. I wonder if that's a combination of the wax paper on the fly and the nicotine that was burnt..

The osc. signal is definitely not properly reaching the HO grid. Test and or replace all suspect parts in the osc, and all parts from it leading to the grid of the HO Tube.

A near 50% positive increase in the HO grid voltage is the main cause of the problem. The HO tube is going to conduct way too much current until it's grid drive signal is made right....I recommend removing the top lead and disconnecting the screen grid (not the control grid) lead from the socket of the H output tube. until you can get the grid voltage back in the ballpark.

Are you still suspecting the horz osc coil is still the suspect? or should I test and replace all caps and resistors in between? I'm going to order up all the caps on that board and replace them anyways seeing how there's a problem, and there are a few resistors in between that are giving wacky results.. I'm still waiting for the tubes as well..

a few things..

what are you using to check the voltages, a VTVM is best.

have you tried a known good osc tube 6FQ7

Note the grid circuit includes a voltage divider as part of the horz hold. Since the grid is too positive a good start would be to check the parts in that circuit,mainly the 22k resistor to ground from one side of the horz hold pot.

I would be scoping the cathode and check the free running freq (no signal) to see if its in the ball park.