Predicta Advice Needed
 

I'm sure my 21" Holliday needs the usual total chassis rebuild, but I'm wondering about something. Right now it does almost nothing when turned on. The vacuum tubes glow, but that's about it. I've read a couple of articles about repairing these (one of them by a member of this forum) and they both mention the 7watt 5.6ohm fusistor. I'm wondering if it will be worth it to replace it with a 6ohm resistor to see if the set will do anything more. I want to find out about the flyback transformer and the picture tube before I decide about having the chassis rebuilt. Will replacing that fusistor possibly get the high voltage going again? I brought the voltage on the set up slowly over several hours in an attempt to reform the old e.caps for whatever that's worth. Any advice or help on this would be great.

"A little knowledge is a dangerous thing"
Dan

I would probably leave the fusistor alone until you have a more stable power supply. Personally, I would replace the E-caps outright before attempting a power up. Your set it much too valuable to risk having one 'reform' and then explode later. If your fusistor is blown, it probably went up for a reason.

But some nice news is that the filament string is going. Do the filaments on the CRT light up? If so, you are about as far along with that until you can get to a CRT checker.

You're right about those flybacks getting toasty. Just on visual inspection, how does it look to you? If you see any major cracks in the donut, or dripped black wax everywhere...trouble. If you see some black sooty stuff lining the high voltage box; that's not so bad as that kind of stuff just gathers in there.

If you don't mind my asking, if you are going for a rebuild, are you going to do it yourself or are you going to ship it on out? If you are a DYIer, I'm sure there are some AKers close to your area who can test out your set for basic worthiness.

good luck,

wade

It's been in storage for a few years. I haven't actually opened it up this time, but I remember some cracks in the donut, but probably not anything major. No dripped wax or anything like that. I tried reforming the caps just to help test the set and see what will do before proceeding. Not sure about the filaments on the CRT, should I remove the little cover on the back and see if anything lights up? I would like to do it myself, but I've only ever recapped one radio and I'm not sure I can swing it. I have the Sam's folder for it, but I'm not great at reading schematics. I would probably be better off sending it out, but that will have to wait until I have an extra $300-$400 laying around.

Follow up
 

I took the little cover off the back of the CRT and it is glowing in there. I was planning on replacing the fusistor and then bringing the voltage up slowly again to see what happens, but if it's not worth it, I won't try it.

Well, you're past the first hurdles now. Probably the next thing I would do is check the tubes. High voltage won't work at all if some key tubes are worn out. Do you have a multimeter and some basic test gear to do a restoration?

I have mostly worked on radios, and I know how you feel-a television is much more intimidating. Luckily, these sets are not too bad to work with once you can get to the main board. As with anything, take your time and results will follow...

wade

O.K., I couldn't resist (no pun intended) I put a resistor in and brought the power up just long enough to test it, and while I still get no picture at all, it picked up the sound from my local ABC affiliate loud and clear without an antenna. The guy I bought it from restores radios as his hobby and he has a working tube tester. I'll make that my next move.

Thanks!
Dan

If you have only recapped one radio and have trouble reading a schematic, this is not a good first project.

Bring it to your friend and have him coach you in understanding a schematic and replacing the electrolytic capacitors, for starters. Or just ask him for an estimate on what he would charge to restore it.

Phil Nelson

I have a Barber Pole model that I've been working on (and off) for the last couple of years....other projects come along/distractions/etc...but I enjoy it when I'm back on it. Even after you re-cap and replace out of tolerance resistors, there still/will be some hidden problems to address. A Predicta is NOT like working on old radios, where you do the above (and replace a tube or two) and you would have something that works! Predictas' have their quirks, but most are common to this model and there is lots of support for getting these things working, especially here!
Phil is correct (and he would know too) about working on them. There are valid reasons why TV Repairmen hated 'em!
My set is in the "operating" stage and I've been working out its issues one by one and I'm not done yet! I do like watching "The Twilight Zone" on it!!
And mostly, do a search here and you'll pull up lots of info.
That fusable link resistor should not just have opened up by itself unless there's some overcurrent. And like you said, you don't have any raster. A bad/shorted horizontal stage tube could cause a current problem or a bad/shorted/leaky cap in the power supply as well as the B+ boost cap could be a problem just for starters....
So having someone mentor you with this would be a good idea. Keep us informed!

The fusible resistor on mine had a lot of green corrosion and had basically fallen apart. From what I've seen that isn't that unusual. I initially replaced it with a plain resistor but now I have a NOS part in there. Mine is the cheapest model (motel special) but works decent after replacing the caps in the vertical circuit. The crt is weak-barely acceptable.

I like you am a Philco fan----mainly of Predictas' and tube audio. I joined after surfing the web like you in hopes of learning things about these sets. I have been collecting Predicta's for only about three years, and have worked on two of them. The first thing you will need to do is get a copy of SAMS 439 folder 2 and get a good VOM. You can check your flyback with the VOM to see if you have open turns on the flyback---sams shows the values you should be reading. Do not be shocked by the look of the flyback---most of the wax will have melted off. I would follow what marty59 said as well about the b+ and shorts in thr horitz. I had to pull the main board up and re-cap the whole set before I did a power up test. Hope this is of some help to you. Also I had to send the tube to Hawkeye to have it re-gunned--I am told this is very common on 21" Predictas.

Thanks guys! I had an old timer help me find a bad cap that had made my other set, a 17" Princess loose it's picture, but he did it as a favor and won't be willing to help me much with the Holliday. He restores radios for a living and quit working on TV's about ten years ago. I haven't kept in touch with the guy I bought the Holliday from (I used to work with him), but he still lives across the street from my parents and I'll check with him to see if he's still into vintage electronics, and if he can help me out. The fusistor in my set looked fine, but had obviously gone bad. The flyback does have some cracks and flaking, but overall it looks pretty good. I do have the Sams folder so that's taken care of. The radio I did the recap on is a Philco 40-160. I did lots of online research and asked a few questions along the way. I ended up replacing all the caps except the mica ones, a few resistors and quite a bit of rubber coated wire. Since I'd never done anything like that before, I checked, double checked and then checked again to make sure I had everything right. It came out great! It probably could still use an alignment, but it works and sounds better than I expected it would! It was a fun project and that's what made me drag the Predictas out of storage, but I better not bite off more than I can chew. If I can't find the help and advice I need locally, I'll probably go ahead and send the chassis out for rebuild sometime soon.

predicta
 

Most important, check fusible resistor first,they are always open from corrosion. This is a series string set no transformer. If you replace it first then try the set you may have sound and raster. You will not damage set.

My avatar is a photo of my 17" Princess playing Twilight Zone. It's probably the perfect show for watching on these sets because they are a little surreal looking anyway. The set's picture looks even better since I took that photo because I managed to polish most of the heavy scratches out of the screen cover and I also opened it up and removed a CRT warning label that had worked it's way down near the top of the screen.