Magnavox Color Analog Television Model 3RT515K

[charokeeroad]

Thanks for the tips. I'm looking forward to testing it. It sure looks good in the pictures. I couldn't find any rererences to it on the Web yet I remember seeing this set growing up. The seller has another early color set. It's a Zenith Color TV Analog Television Model X4518. I'm only interested in the roundie.

[Steve D.]

I agree that this is a '64-'65 Magnavox. Both model years used the 45 series chassis. It can be found
in SAMS set 76, folder 3. Depending on the model the CRT will be a 21FJ or 21FB.

-Steve D.

[Tim]

I've got a similar set in a different cabinet style. Found at an estate sale for $20. Model 20T548K with U45 chassis dated 1965 and has a good 21FBP22. I installed some missing tubes and it came up working well on original parts and runs with cool filters. Don't see these too often. Hope you get the set.

[charokeeroad]

Thanks for the feedback Steve, Great looking set Tim.

This set will be just a bit more than 50 bucks but I haven't seen this set here in a long time. Usually they're gone before I get to them. It would be great if all I had to do was pop in a few tubes and I could be watchin it that night. ..

If I get it it will be my first color set.

PS Cool Website Steve!

[charokeeroad]

The seller wasn't quite ready for me when I got there. He had to move a few pallets and dig the set out from under a tarp. The set was one of three on the pallet. The Set I was after was on it's side and another set was on top of it. They were able to get my set unloaded and set on it's legs. The back was off and the cap was badly damaged. It's the one you can see in the picture with the back off. I decided to test it anyway since I had already made the drive. Surprisingly all three guns had emissions.

The red gun was 860 the green gun was at 880 and the blue gun was at 880 also. I made one heck of a deal on the set, packed it up and took it home.


The seller said they had a fuzzy picture on it before they put it on the pallet so I turned it up on the Variac when I got it home. The small tube started lighting up at around 90 Volts but after a minute or two I could hear some crackeling sounds coming from the HV area so I shut it off until I can get a chance to recap it and look for other damage or defective parts. At least I know it has a very good 21FBP22A. I need to look for a new cap for it hopefully someone will have one they will part with.

[DaveWM]

FYI that era of set often does not need a lot of work to get going. The main thing you want to watch on power up is the cathode current of the horz out, use a bypassed analog meter is best. Monitor the HV at the anode, and the AC line current (my variac has a AC volt and AC current). Typical current at the line at 117v is about 3.5amps

watch the cathode current on the hot, you dont want it to go much over 200ma, watch the HV you dont want it to go over 25kv. I generally pull the horz out and the vert out tubes, and then do a slow monitored power up, checking the filter cans for heat, while monitoring the B+, I variac up slowly watching the AC current and stop when the B+ hits about 400vdc. I generally turn it up about 10v every 30 min or so, all the while checking the temps of the cans. If all that goes well then put the horz and vert out tubes back in and do a full power start up. You dont want to go slowly with the horz out in in place.

If the HV starts to go over 25kv pull the plug same with the current if it goes over 220ma just pull the plug.

Welcome the the wonderful world of color.

My guess is the set will work just fine, maybe a shorted tube or two, often not enough to really keep it from working somewhat. these sets are not the headache cap wise that your 40's and 50's sets are.

Mostly dirty controls, and sometimes corroded wires.

[charokeeroad]

Thanks Dave for taking the time to write that up. I 'll follow your instructions to the letter. Don't want to loose this really fine looking set to anymore improper handeling. Any comments on the CRT readings? If I found a B&W CRT with those reading I'd be thrilled. What I did notice is that the readings are very close between the different guns. The circuit boards didn't look like they have had any work done on them but that was just a brief observation. I think I'll do a tube test before I do the start up procedure, I might be able to catch a bad tube right away.

[DaveWM]

Your CRT sounds good, balance is important for good gray scale at different brightness settings.

Checking the tubes for shorts is a good idea. But keep the old ones around, some tube testers are super sensitive and sometimes a mild short is no big deal.
I quick smack on the table will often clear them up.

remove the safety cap that will be across the line before plugging it in. They are generally the white elmenco brand tubular caps sometimes they have two from the interlock to the chassis, sometimes just one across the interlock.

After the initial check out you will have to decide which camp you are in

A) replace all electrolytic caps with new

B) keep old caps in but use a fuse just after the B+

I would say that prob 80% of my sets from the 60's have the orig cans, but I would not bother to debate the pro or con as I can see why some would prefer to just replace. My only comment would be to at least baseline it with the caps in there (using the described procedure to avoid a dead short cap) then do the replacement. the reason being if you induce a problem during the work you can at least know it worked before so you can focus on just the work you have done.

On older sets I still do not automatically replace, but rather do a more extensive test on the caps by removing them from the circuit and then testing each section with an old school cap tester, often reform them in placed over a 24-36hr process using the cap testers variable power supply.

IF the cap comes back and test like a new one I reattach and use it.

The problem with older sets is they often have tube based power supplies so the variac does not provide the very low reforming voltages as the 5U4 is not conducting that low. newer set have SS diodes so you can get the very low startup voltages out of the B+.

Your set 'may" have a doubler from B+ so if that can is open (look for one with a cardboard sleeve) then the process is not going to work as well.

I generally check that one before doing anything. The doubler has to be in pretty good shape since its part of the B+ supply (not a filter).

[DaveWM]

on checking the HO Tube current, some sets make it easy, some not so, but the easiest way to do it is to use one of those tube socket things that have two wires coming out that break the cathode for you. Every once in a while they will not work (like if the suppressor screen is grounded and the cathode pin is wired to it then the ground). Also be careful handing the top plate lead fo the HO tube. Its easy to break off the top plate cap from the tube, and also the wire itself is ofter brittle and will break easy. I hold the tube upside down and spray in a pot cleaner, let gravity pull it into the joint of the cap plate connector and the tube leave it be for about 30 min, and then it should come of with a little side to side rocking action.

I also will add a wire to replace the jumper that is often used in the cathode circuit, just a insulated wire with a spade connection with the other side of the connection bolted to the chassis in the back. this make it very easy to test the HO tube cathode current (esp useful with the socket thing did not work).

[charokeeroad]

Hey Dave, I did some tube testing and found mostly good tubes but a few that will need to be replaced before I start applying voltage again. The Chassis number is U45045 91 and the date is 07/65.

Attached is the tube lineup and test results. I'll order some tubes this weekend and hopefully have them in place by the end of the week when we can get back to the start up.

[DaveWM]

I think my maggie combo had the U45, its like a RCA clone circuit wise (ctc-15) but the power trans and Flyback are flipped around. some of them had the stick focus some had the tube focus. Pretty sure it used the doubler rather than the full wave rectifier like the CTC-16's had.

[DaveWM]

Link to my U45 fun

http://videokarma.org/showthread.php?t=251118

[charokeeroad]

From what I see in the pics the chassis of your set in the link could be the exact same layout as mine. Mine does have the HV cage. From your pics I can see what's inside the HV cage. When I was doing my tube test I popped the lid and felt around inside just to see if there were any other tubes in there. I can see from your pics that there aren't. Looks like you CRT has very good emissions also. I'll check out the whole thread this weekend.

[charokeeroad]

Dave can you take a look at my tube line up and tell me which tubes to pull to do the slow start up sequence?

Thanks

[DaveWM]

6JE6 and a 6GF7 on the vert board.

Give me a call and will talk