flyback cooling

[DaveWM]

dont think I will bother with the thermistor, the experiment has proven to me the only way to really keep it under 100f is a 3" muffin right at the base. I will prob just figure a way to mount it there and leave the cage off. I am not worried about fire as I never leave it running unattended, and I assume the x rays if any are still going to be shielded by the reaming 1/2 of the cage which effectively blocks the front (where I will be viewing).

While a 12 flybeck is not that hard to comeby my CTC-5 and CTC-9 are a bit harder. I was hoping to learn about best ways to add active cooling on this set but the real target are those.

I may get motivated and build a cage with the bottom cut out for the larger fan.

[DaveWM]

I used some very thin copper clad (both sided) material to fab up the cage. It was very easy as the material would bend sharply and you can burnish in a nice 90 degree bend. holes and cut outs are easy with some curved small scissors.

I folded in the tops about 1/2 inch and lap seamed with solder to hold its shape.

I still need to fab up a top, but will wait on that until I test it out.

cut a large round opening that puts the fan right at the side of the fly, used some silicone dabs in the corner of the fan to hold it in place, spaced up the fan just a bit from the copper (I am hoping that will keep the vibes from the fan from being amplified by the thin copper).

I will take some pics tomorrow after the silicone has a chance to setup. I only have about 1 hr total fab time into it so if it does not work its no big loss.

I will still have to make up a DC power supply, I think the filaments would be fine with a 1/2 wave and a 100uf filter cap.

[DaveWM]

I could not wait, the silicone had set up enough to hold the fan so I installed the cage and hooked up a 9v battery.

Its very quiet

when the HV comes up the fan slows down, perhaps the fly is effecting it, like when the neon bulb lights up near the tire.

the air is restricted by the close fitting back, I can put some spacers on the cage that should keep at least some clearance for air to get by, but its not ideal, and there is no real good way to mount it as one side sits next the horz out tube, one side is against the side wall and one side is on the back. I may have worked better if I just mounted it on top and aimed it down but I liked having the fan right up near the fly.

[DaveWM]

ok not gonna work, I had some arcing from the fly to the fan, that can't be good and the fan does slow down a LOT that close the the tire.

so its back to mounting the fan on the top and just letting it blow down. so will try that again.

[Charlie]

Originally Posted by DaveWM

I had some arcing from the fly to the fan...

That would certainly slow me down!!

[DaveWM]

yea you could hear the fan slow to about 1/2 speed as the HV came up, yikes.

I think keeping the orig cover with the top off and a sheet of mylar to guide the air downward may work as well. Other sets with more room would prob work fine, like my CTC-5 which has the top of the cage that can be removed and has plenty of space for a fan.

[DaveWM]

one more try , this time with the fan on the outside of the box, far enough away from the fly to not slow down, but it would be completely outside the back of the set which would mean I would need to cut a square hole in the masonite back, not going to happen...


but it sure works well, been on for over 1 hr and its about 95f, and does not seem to be getting any hotter, I suspect I could run it all day and thats as hot as it would get.

So one more try this time I will try side mounting 3 of the little fans along the side by the HO tube. Since they are small I am pretty sure they will fit there, so I will have a 1" wide by 3" tall hole on the side.

[DaveWM]

I think I got it worked out.

I cut a third hole this time on the fly cage side next to the side of the cabinet, I can stack two of the mini fans in there and get them pointed right at the flyback, about 1" away from the tire. the fans suck air thru a very tight dead space, but there is at least a 3/4 inch space so they are not starved off and the back can go back on.

The down side is the fans are very noisy so I will have to see if I can do anything about that. I would love to get the 3" fan back on the side I just dont think I can get it to fit and still be able to install the cage.

[frenchy]

Mentioned at the start of the thread - running sets without the HV cage. If this did help cooling a bunch, is it a good idea other than that? I was thinking it might be asking for trouble if a wire elsewhere in the set happened to stray over there while it was running, though precautions could be taken in that case. Other than that there is the basic safety factor of some kid sticking a screwdriver thru the back or whatever. Also would lack of the cage make arcing less of an issue, since then there wouldn't be a cage there for arcs to jump to?

Also mentioned was using a solid state HV rectifier. I still do that in some of my color sets (not my b/w sets), but have heard scary things about them possibly shorting and then taking the flyback out along with them. I have left them in though. I also use the little solid state focus rectifier substitutes and worry less about those since the voltage is only 1/3 of the ultor voltage. I simply like the idea of taking those two filament loads off the flyback so it doesn't get as hot in the first place regardless of cooling methods, but I guess if one of the SS plugins ever does kill one of my flybacks I'll change my mind. : )

I've thought about adding fans and such but as noted, I would definitely worry about that bringing in lots more extra dust. In the long run, I run my sets infrequently enough and for such short periods when I do, I'm not really worried about the flyback getting any more melted than when I got the set, nor about those SS diodes shorting out.