Rare find! A Magnavox Brittany tv! - Page 11 - Videokarma.org TV - Video

Yamamaya42 · #**151** 05-20-2025, 06:53 PM

I don't think it will be able to jump that gap again!
http://suzaku.live-evil.org/0520251839.jpg

looks like crap though! but it was made from 2 broken transformers.

Yamamaya42 · #**152** 05-21-2025, 02:15 PM

If this flyback transformer patch does not work, or fails again, I have found a way around it, but it would doing a “Shango066” with it, I have found a RAM type FBT made for RCA 630 circuits, 13kv output like this needs, but w/o the voltage doubler, b+ is the same, boost is slightly higher 510 vs 500, very close.

Yamamaya42 · #**153** 05-21-2025, 08:26 PM

Ran it for about 15 min, no smoke, no fire, no arcing, so far so good!

bandersen · #**154** 05-21-2025, 09:30 PM

Fingers crossed

Yamamaya42 · #**155** 05-21-2025, 11:35 PM

I Did order a NOS RAM X032, just in case, the one i have failed, not quite the right one, but I cant find a X077, this can be made to work in a bind.

http://www.earlytelevision.org/pdf/r..._reference.pdf

Yamamaya42 · #**156** 05-26-2025, 12:29 PM

Ran OK for about an hour last night, no major issues seen, the FBT is getting a bit warm, i guess that they are driving it hard, not to mention there are 5 tubes around it, gonna try some small heat sinks on it and a bigger fan.

Yamamaya42 · #**157** 05-27-2025, 11:13 PM

http://suzaku.live-evil.org/0527252003.jpg

So, perhaps this and a big fan will help it keep cooler? a bit perhaps. :P

timmy · #**158** 05-28-2025, 11:39 AM

Why put a fan that was never intended for some things I was told with the old sets that they are supposed to get hot to work right. A fan to cool a hot flyback I don’t think that would be much help since the heat comes from within the depths of the flyback. I guess a type of shield to keep tube heat away would help.

Yamamaya42 · #**159** 05-28-2025, 11:55 AM

I tend to think that this was a foolish design from Magnavox in the first place, not well thought out for longevity, 2 horizontal output tubes, 2 HV rect tubes, 3 candohm resistors and a FBT crammed into one metal box, it's asking for things to fail, I'm pretty sure that the flyback transformer that was in there when I got it was not the original, it's been replaced before, and the one I took out looked very toasty, and replacements are very hard to find, so like my other sets, I will take steps to keep it as cool as I can.

Electronic M · #**160** 05-28-2025, 12:21 PM

Quote:

Originally Posted by timmy

Why put a fan that was never intended for some things I was told with the old sets that they are supposed to get hot to work right. A fan to cool a hot flyback I don’t think that would be much help since the heat comes from within the depths of the flyback. I guess a type of shield to keep tube heat away would help.

Flybacks are not supposed to run warmer than bath water. If they do either something in the circuit needs attention or extra cooling is necessary. Sweep circuits don't need to be hot to work. The tuner and IF might as the caps are sometimes temperature dependent for exact value for proper alignment behavior.

Yamamaya42 · #**161** 05-28-2025, 12:48 PM

Quote:

Originally Posted by Electronic M

Flybacks are not supposed to run warmer than bath water. If they do either something in the circuit needs attention or extra cooling is necessary. Sweep circuits don't need to be hot to work. The tuner and IF might as the caps are sometimes temperature dependent for exact value for proper alignment behavior.

Exactly, I don't like how warm it's getting, and don't see anything circuit wise that could be pushing it so hard, everything is new, other than dropping to one HOT, than 2, perhaps that will cool it down a bit?

Electronic M · #**162** 05-28-2025, 07:58 PM

If it works on one tube, the cathode current isn't beyond specs for the tube, and it doesn't somehow run the flyback hotter it's probably fine. It can't hurt to try...If one tube has a sudden failure the same condition would exist so the designers should have at least considered the probability of it happening.

Yamamaya42 · #**163** 05-28-2025, 11:02 PM

Quote:

Originally Posted by Electronic M

If it works on one tube, the cathode current isn't beyond specs for the tube, and it doesn't somehow run the flyback hotter it's probably fine. It can't hurt to try...If one tube has a sudden failure the same condition would exist so the designers should have at least considered the probability of it happening.

http://suzaku.live-evil.org/0528252248_Burst01.jpg
It does say to use one tube for the AP4 and 2 for the EP4, and I did get it with FP4 but am putting in a LP4 that has an angle closer to the AP4, so I guess the dual is not needed, but if it means the FBT will be cooler... who knows.

Yamamaya42 · #**164** 05-30-2025, 11:14 PM

I'm starting to thing that this silly thing just runs the FBT hot, and they knew it when they made the set.
Like see the pic of the old one.
http://suzaku.live-evil.org/0226251827b.jpg

they had it bolted to that copper plate, that was not for ground, or mounting, it was to cool the damn thing off!
and even so, it still got toasted!

I'm gonna put a big Vantec 80mm Tornado Case Fan on that thing!

Yamamaya42 · #**165** 06-02-2025, 08:53 AM

I did try it on one tube over the weekend, it SORT of worked, but did not like it, it was unstable, would lose h-sync when power cycled, much more stable with both tubes, comes up with lock each time.

Still don't like how hot the FBT gets, but at this point, there is not much more I can do about it, as it seems to be the way it was made, I will attempt to put some heat sink paste between the FBT and the large copper plate they have there for cooling which I hope will pull the heat away a bit better, there was nothing originally, this plus a massive case fan will hopefully keep it from frying.

The focus coil also gets rather warm, this I'm guessing is normal as they had a 5w 560 ohm resistor and 5w wire wound 2.2k pot in the circuit, both of which fried when the pot failed and shorted to gnd, I could not find a suitable 2.2k pot in the right power range, so I got a 5k 5w wire wound, this should not be a problem as only one end and the center is used, and the 16LP4 uses a bit less focus current than the 16FP4 that was in there, so the extra range won't hurt, 146ma vs 110ma, I still have to clean the rust off the focus coil and fix the disintegrated covers on the yoke.

Overall, I'm impressed with the level of detail I'm seeing in the video on the 8YP4, even though it's not a good match to the set, and it's smearing, it means the IF is pretty good, and so is the video sections.