To EHT, or not EHT?

[Down Under]

Hi all,

I finally had some time to work on my Princess Predicta. I have 3 Predictas that I bought on eBay and had shipped to Australia, they're such a great looking set.

I have the Princess, Debutante and the Holiday. I have recapped (mostly) the Princess and I have an interesting problem. If I leave the yoke disconnected, I get a healthy arc from the flyback and a dot on the screen with the gun connected to its socket. Luckily I had the brightness all the way down, I would have hated to have ruined the CRT with a dead spot in the middle!

If I connect the yoke, I lose the EHT, and the 6DQ6 red plates. Boost volts are too low, about 288V. The grid of the 6DQ6 is around -44V. I tried the yoke from the debutante thinking I might have had a short, but same result. The flyback tx readings in terms of resistance measure OK. (I badly need a CRO) I have replaced the sockets of the 6DQ6 and the 6DA$, and pulled the board for a complete examination. A few of the tracks had been (badly) repaired but I cleaned those up. It's very handly indeed to be able to compare readings etc. from the Debutante to the Princess, as I've pulled both boards.

Any info on this issue would be very much appreciated, along with the orig Philco manuals or a link to them. I have the Sams manuals, but I luckily found on this forum the pin location IDs to the main board, which has helped me no end. I bought some push on pins to save a lot of time when removing/fitting the board for testing. A Brother P-touch and lots of numbered labels works very well indeed. The Philco manuals are good in that they match the part numbers listed on the board. Am I the only one who wonders why they used their own numbering system?

Lastly, I'm looking to buy a Mahogany Tandem, but that's for another post...

Cheers,

Adam

[kvflyer]

Hi Adam and welcome to VideoKarma. Whilst I don't have your answer, my daughter and family live in Rosanna and work in Melbourne. Hopefully, we can "hook up" some time when I am visiting (which is frequently!). Now let's get this problem sorted out...

[Down Under]

Hi Kvflyer,

That sounds great, it'd be fantastic to see someone else who is into this.

I'll keep the beers cold for you!

Cheers,

Adam

[Phil Nelson]

Originally Posted by Down Under

The Philco manuals are good in that they match the part numbers listed on the board. Am I the only one who wonders why they used their own numbering system?

What was the alternative? As I understand it, Sams manuals were made after the fact, when the set was already in production (or sufficiently finalized to ship, anyhow). So Philco could have made up their own numbers or used none at all.

The Philco manual is definitely better than Sams. I got mine from some dude on eBay.

Phil Nelson

[DaveWM]

are you sure of the wiring of the yoke to the fly? check for resistance at least.

does the -44 go away with the yoke attached?

[Down Under]

Originally Posted by DaveWM

are you sure of the wiring of the yoke to the fly? check for resistance at least.

does the -44 go away with the yoke attached?

Hi all,

I'll have to try ebay for the Philco manuals, there was a guy selling them on CD, but he wouldn't ship to AU as he said he was unable to get to a post office

As the the -44, yep, it's still present with the yoke conected. The resistances seem OK, no dead shorts or anything horrible. Both yokes read the same, so I'm guessing they're OK. By memory the HOR winding was around 47ohms.

I should mention that there is still one original can electro in place, the largest one near the vertical OP tranny. I will be replacing it but I just don't have all the new caps yet. Not sure if that's important or not!

Cheers,

Adam

[Glenz75]

Welcome to the forum Adam This is a great place for all of us vintage TV enthusiasts (nutters ) and the people here are great and very helpful with their wealth of knowledge and information.
You obviously like those Predictas enough to have imported three of them! They are a neat looking set. There are also several sets that I'd love to import to NZ myself from the US as well including some colour roundies ...Maybe one day.
Good luck with your Predtica restoration projects....

Cheers
Glen

[Down Under]

Thanks a lot Glen,

yes, I'd call myself addicted! The Predictas have certainly created an impression at home, but I really want to restore them to their former working glory to fully appreciate them. If you're in NZ, you'll also understand the freight costs to get these beauties over. I've been lucky, all of my sets have arrived exactly as they were packed.

A colour roundie, I didn't know they even existed until I read various posts in this forum! By the time we had colour TV in AU, the tubes were well and truly rectangular. Even the early BW sets were mainly rectangular!

I was lucky enough to get an HMV rounded BW set, haven't looked at it yet, but it shouldn't be too hard hopefully as I have the squarer version alreay working.

Catchya,

Adam

[kvflyer]

Originally Posted by Down Under

Hi all,

I'll have to try ebay for the Philco manuals, there was a guy selling them on CD, but he wouldn't ship to AU as he said he was unable to get to a post office
...

Cheers,

Adam

Hi Adam,

Let me know who this guy is on eBay and what the item number is. If you can't find another way, I can get the CD sent to me and then send it to you. Trust me, I know a little about posting and traveling to Australia!

Cheers Mate,
Don

[Down Under]

Hi Don,

thanks very much for the extremely generous offer, he 's not advertising at the moment, but I can always ask him if he'll send locally if he does again. Apparently his legs don't work, so he's house bound and only wants local pickup of the CD's. I was even willing to have him email me the files if I paid for them, but he wasn't interested.

Pity about that becuase from what I keep reading, the Philco manuals are better than the Sams ones. I have a Philco cct diag from ARF, which I'm really grateful for. I'm now looking for a CRO in AU and possibly a TV analyser as well to feed in various H and V drive signals.

Anyone know about my issue? I feel as though I'm missing something really basic, I do have replacement electros on the way for the big can, but I'm wondering if K7 couplate from the HOR OSC to the 6DQ6 may be causing the loading down problem. It's all OK until either yoke is connected, then the EHT dies to almost nothing, and there's no glow from the rectifier tube either. (To be expected.)

I'm assuming that running one of these TVs at a mains frequency of 50Hz instead of 60 Hz wouldn't be too major? I would think that with these sets, there'd be a lot of room for error. Obviously I have to use a 240V to 110V transformer, but that's easy.

Cheers,

Adam

[DaveWM]

did you check the screen voltage of the HOT? If you have a good drive signal I would start by subbing in a new HOT/Damper as well. Is the Damper filament staying lit the whole time, I had a bad ground stake that would cause it to go out.

[Down Under]

Originally Posted by DaveWM

did you check the screen voltage of the HOT? If you have a good drive signal I would start by subbing in a new HOT/Damper as well. Is the Damper filament staying lit the whole time, I had a bad ground stake that would cause it to go out.

Hi Dave,

I've subbed a new 6DA4 damper, and I've also replaced the sockets of both the HOR out and the Damper tubes. All of the filaments stay lit, but I haven't checked the screen voltage of the HOT. (Just so I know, are you talking HOR out tube, or HOR out transformer?)

I'm assuming you mean the 6DQ6 o/p tube.

Cheers,

Adam

[Glenz75]

Hi Adam, yeah me too addicted definitely...Last count about 20 plus old TV sets so that kind of says it! I don't know if you have had a look at my blog and that shows about half of what I've got..there is still a few more to add when I get time.

It must have cost you a small fortune to have all three of them shipped to Australia, and New Zealand it'd be pretty much the same, thats why I haven't even looked into getting anything from overseas...cost and the risk factor of it arriving damaged.

We were pretty much the same here in NZ with television, didn't officially get TV until around 1960 and colour came in 1974 so no hyrid or full valve colour sets at all and like in AU all our early sets were rectangular CRT's also. Some very early round CRT UK sets did make it here, but have never seen one and being 405 line they wouldn't have worked very well here being 625 line.

The earliest NZ made TV set I own is a 1959 Pye which has a 90 degree CRT and is very English looking in its layout etc. I'm only just got them (two) recently so and yet to look at those too.

Cheers!
Glen

Originally Posted by Down Under

Thanks a lot Glen,

yes, I'd call myself addicted! The Predictas have certainly created an impression at home, but I really want to restore them to their former working glory to fully appreciate them. If you're in NZ, you'll also understand the freight costs to get these beauties over. I've been lucky, all of my sets have arrived exactly as they were packed.

A colour roundie, I didn't know they even existed until I read various posts in this forum! By the time we had colour TV in AU, the tubes were well and truly rectangular. Even the early BW sets were mainly rectangular!

I was lucky enough to get an HMV rounded BW set, haven't looked at it yet, but it shouldn't be too hard hopefully as I have the squarer version alreay working.

Catchya,

Adam

[DaveWM]

yes HOT to me is Horz Output Tube, I refer to the horizontal output transformer simply as the "fly or flyback"

Too bad you do not have a TV analyst, I find them helpful for quick trouble shooting of HV. I doubt its a couplate if the grid signal is still good with the yoke attached.

[Down Under]

Hi Glen,

I'll check out your pages very soon, it's always very interesting to see the sets that people have. (And where they manage to put them all!) I have a total of 6 at the moment, but only the squarer HMV working for now) As I'm renting, I haven't got a proper workshop which is very frustrating.

The Predictas cost about A$700.00 to freight each, packed in a box inside another box, lined with foam. The sellers I've bought from have been excellent, the only annoyance happens when I see a TV I want on ebay but the seller won't ship. The Holiday I bought was listed 3 times before I came along and bought it, the seller mentioned on the 2nd and 3rd listings that the previous winning bidders were put off by the freight costs. I paid a fortune for this, and prices have dropped since. But I have it, it's in excellent condition, and I love it. Can't wait to restore it.

I also had a small GE 17 inch set brought over, and all 4 US TVs have arrived intact. Asking the seller to remove the CRT plug and pack it aside so it can't break the neck of the tube can help, but I've only had that happen once, and all of my tubes are OK. (Not sure about emissions on the Holiday tube yet!)

Catchya,

Adam