View Full Version : porthole flyback shorted - any replacements ?


kramden66
08-02-2013, 02:33 AM
If you've been following the 24G26 thread i was there , it was up and running , well to try help with the somewhat unstable horz hold i decided to try changing some of the sync and horz tubes , to my shock i lost raster , went up and down everything and couldn't find anything wrong , no hv on the anode , so i hooked up the fly tester and it shows a shorted fly.... so my question is is there something i can sub it with , the fly i listed in the wanted will do it , also the fly listed covers multiple zenith portholes including the 10" mayflower , i think it was Eric H who adapted a fly-1 to that set , could a fly-1 work here ? or is there something that could sub ?

sorry did it again posthole instead of porthole.

thanks
mike

Einar72
08-02-2013, 09:54 PM
Have you checked to see if the Damper filter is shorted? I brought home a beautiful porthole in '86, plugged it in and started watching Johnny Carson. After 30 minutes, I heard a crackling, and turned it off. The donut was melting off the windings!

Next day, I found the problem. A .047 cap at the Damper tube measyred 47 ohms! Yes, 'twas a bumblebee. So, check for that particular cap before you install that fresh flyback. Do you have the Zenith P/N off of it?

Eric H
08-02-2013, 09:56 PM
Fixed that typo for you.

Yes I did sub an RCA Fly 1 in a Mayflower 10" set, it worked great but that set uses all the same tubes in the horizontal and HV section that the RCA does, not sure if your model does or not, i.e. 6BG6 sweep, 5V4 damper, 6SN7 oscillator, basically the same circuit as the RCA, had to change the yoke network to match.

The Fly in my set was fried to start with and it looked it, it also went up in sparks when first fired up, if yours doesn't meet any of those criteria then I would suspect something else may have quit, possibly the Horizontal Oscillator?

Einar72
08-02-2013, 10:07 PM
Hopefully, this may help:

kramden66
08-03-2013, 03:24 AM
i will recheck but it has been recapped and the fly checker shows a total short , now unless theres something at the damper socket thats causing the reading from experiance with the fly checker on other flys it has to be the problem, i don't think the doorknob is at fault either.

Eric H the only reason why i thought of fly-1 is because you put one in your mayflower , my mayflower has a ram fly in it that was put in i don't know how long ago , someone sent me a picture of that ram box because i wasn't sure it belonged in there and thought maybe someone made an attempt and it wasn't right, well the box lists several zenith flys it will replace , the mayflower is one but the fly number in this porthole is also on that list , this is why it hit me if that ram fly can be used on two different sets one with 6BG6 and the other with two 6BQ6 tubes then why can't fly-1 work ?
this would be a real headache but i could take the fly out of the mayflower and put it in the 24G26 and put the fly-1 in the mayflower like you did but it would be easier just to put the fly-1 into the 24G26

i suppose i could try studying the wiring of the mayflower vs the 24G26 and see if they are simular in anyway and try to see if the resistances on them are close but the trouble i have is theres no sams for the 24G26 and the model before it 24G24 or 24G25 i don't knbow if theres a sams and the service manual i don't think lists resistances of the fly.

thanks for the pictures but i can't read them too clearly

mike

Eric H
08-03-2013, 04:17 AM
There has to be a schematic for the 24G26 somewhere, perhaps Riders?

I just hooked the Fly up wire for wire, they had the same connections just a different configuration. If it has the same tubes as the mayflower I suspect it would work.
The Fly 1 doesn't even get warm in the Zenith and is a much better built part, I never see a bad one in an RCA but Zenith is notorious for bad flybacks.

kramden66
08-03-2013, 11:48 AM
Here is the schematic , i didn't study it but was comparing the two and most of it wires up the same - i think , compare it to the mayflower if you can please.

mike

Eric H
08-03-2013, 03:50 PM
Well they are wired the same but the tube lineup is quite different, I suspect it would make some high voltage but what the side effects might be I don't know.

Is your set a 16" CRT?

kramden66
08-04-2013, 03:07 AM
Yes its a 16" , this set is going to make me out to be the boy who cried wolf , i didn't do anything to it and turned it on and bingo there was a picture , you can imagine my shock , so i hooked the fly tester up and now it doesn't read short , so i decided to check some micas and one of them was leaking , replaced it and now the horz will hold and lock properly.

on the third turn on the fly made a nasty whine and squeal , and there was no picture , i rotated the drive and boom on came a picture , darker and the right side pushed and squeezed in , the drive and width had no effect , i measured the hv and it was only like 8k or 9k , so i yurned it off , 10 minutes later it turned on properly , tried it again a few minutes ago and it ean for 10 to 15 minutes no issues.

one of the attatched pics is the fly , i know its not a great picture but as you can see the fly doesn't look the best.

mike

kvflyer
08-04-2013, 08:02 AM
Looks good!

That fly kinda looks like the one in my porthole (which is still in queue for restoration).

http://i1067.photobucket.com/albums/u435/kvflyer1/Port_fly_web_zps3caecfe7.jpg

I have not done anything (no power up) to this set other than replace the zero emission CRT with a good used one. I promise to do a step by step restoration with documentation when the set gets to the top of the queue. Sorry if I wandered, just want you to know... you are not alone with that toasty flyback...

cwmoser
08-04-2013, 08:52 AM
Mike, your Fly does not look good, but the video is outstanding.

Carl

kramden66
08-04-2013, 12:47 PM
kvflyer that fly looks cooked like mine but hopefully it will work , can't see the round part , if it does i would follow the advice given to me and get the ma current down going to it , these things do get hot and less hot when the ma is proper , i suppose these things could have been saved earlier in their life.... i really recommend fly checkers , they also do yokes but i never tested a yoke with one.

the nice thing about the set is alignments act right so no sound adjustments or video if ones needed its just that damn cooked fly , i suppose as long as it works i will leave it, its a good thing i wont be using it a lot .

mike

kvflyer
08-04-2013, 05:39 PM
kvflyer that fly looks cooked like mine but hopefully it will work , can't see the round part , if it does i would follow the advice given to me and get the ma current down going to it , these things do get hot and less hot when the ma is proper , i suppose these things could have been saved earlier in their life.... i really recommend fly checkers , they also do yokes but i never tested a yoke with one.

the nice thing about the set is alignments act right so no sound adjustments or video if ones needed its just that damn cooked fly , i suppose as long as it works i will leave it, its a good thing i wont be using it a lot .

mike

Mike,

Keep your fingers crossed for me please. About two years ago, one of our members on ARF had a boatload of flybacks. I got an NOS Merit, can't remember the number, for $12.00. I will certainly try the original. For that matter, that fly will give me an opportunity to try out my flyback ringer! I can't wait to get into this set but other things are more important and that thing is full, I mean full of paper capacitors from bumble bees to you name it.

Again, sorry for derailing this thread...

kvflyer
08-04-2013, 05:44 PM
Mike, BTW, my porthole had a 10 amp, yes, you read it correctly, 10 amp fuse in the horizontal section. I think it would be what one would call a "NoBlow" fuse...

Eric H
08-04-2013, 05:52 PM
What might work if it's shorted is to clean the dust off and spray it with some Dielectric Epoxy paint. It's thin enough to seep into the windings and seal any bare spots.

I fixed the HV transformer in a Raytheon this way. It wasn't really shorted though, just arcing internally somewhere.

Ignore the price on this link, that's for a case of the stuff, it's about $8 a can locally.

http://www.uneedit.com/industrial-equipment/chemicals-lubricants-paints/paint-paint-supplies/aervoe-insulating-epoxy-epoxy-insulating-coating-205-403

kramden66
08-04-2013, 06:31 PM
kvflyer good luck with it , the amount of capacitors is nothing compared to some dumonts and rca sets , beware of mica looking or micamold caps that are really paper/wax type values like .001 , one i missed in my set caused the whole vertical to not work.

Eric where do they sell that stuff ? wont hurt to apply it maybe it will cure it .

btw those pics show the set not totaly adjusted as far as vert and horz and the contrast is up all the way , shows that the crt had better days but watchable with a brightner , without it the image slowly gets a little darker and less blacks or if started up from being cooled off its just darker and less blacks.

mike

kramden66
08-05-2013, 01:22 AM
oh now you can see my test pattern in the picture - the sonar circle in the begining of voyage

mike

cbenham
08-06-2013, 11:13 PM
Mike, BTW, my porthole had a 10 amp, yes, you read it correctly, 10 amp fuse in the horizontal section. I think it would be what one would call a "NoBlow" fuse...

I would replace that 10 amp fuse with what ever is noted in the schematic or on the chassis. Usually a 0.25 amp type.

The 10 amp fuse could cause a fire and that would not be a good thing at all.

John Marinello
08-16-2013, 11:35 AM
Your pictures look keystoned, so you likely have shorted windings in your yoke.

old_coot88
08-16-2013, 12:30 PM
Looks more like perspective effect from the camera angle.

kramden66
08-16-2013, 10:09 PM
yes odd angles , it is laying on its side and difficult to take pics head on