My capehart lives....

[jpdylon]

An update to this thread!

What an excellent end to thanksgiving day!

Since I had the last two days off, I decided to jump back into my capehart project. I installed the decent CRT I got from another member and put it back in the cabinet loosely. Corroded CRT base and socket pins were to blame for a dead heater condition at first.
Repeated HO Drive and ion trap adjustments helped the very dim picture.

Right now it runs, but still needs lots of work. Problems currently are:

1. Still a bit dim. If I play around with the AGC and fine tuning it improves slightly, but I suspect video troubles. CRT voltages are good, as is HV and CRT emission.

2. Vertical height lacking --but only slightly

3. horizontal sync extremely weak. It loves to pull and tear like crazy. Took me 15 mins to get it right for the screen shots.

4. Sound and picture will not tune

5. Very poor RF sensitivity. Even with -15db of signal direct from the cable I still have snow. Local channel oscillator (s) are way out of adjustment.

All of the problems improve as the set stays on longer, so I suspect drifted components in most cases. I've linked some movies i took when I first powered up the set.

First start.


And after some tweaking (ok lots of tweaking)



Screenshot:


I'm stoked! It's coming along now.....

[Sandy G]

Yeah, but, YOU HAVE A PICTURE !! (grin)

[Dan Starnes]

That is progress!
Dan

[Keefla]

very very cool!

[MRX37]

One can post videos to photobucket eh? I shall keep this in mind.

Glad you got the old beast up and limping. Hopefully with the right tubes and some tweaking, you can make that thing strut!

[jpdylon]

I replaced quite a few out of tolerance resistors in the vertical section and in the HO drive section that were producing size irregularities. A new RF tube cleared up the snow a bit and some horiz osc and phase adjustments stopped the tearing. Touched up the tuner oscillator and Local channel oscillators and got the tuner working right.

However the problem that remained was snow. The amount was the same regardless of signal input. I was pulling my hair out trying to figure out if the tuner or AGC was at fault because I thought the IF strip was fine.

When I started poking around the IF strip I discovered that the video carrier signal was very weak --next to nothing. I replaced some bad resistors in the last IF stage and touched up the 26mhz slug responsible for the video carrier signal to the detector. I adjusted for maximum signal without overloading.

I watched the set for a good hour or more before i put it back in the chassis. For now, its done! It has a great picture and clear sound. I am very happy with the outcome --especially since its been over a YEAR since I got the set.

Thanks to all who helped me on this set, Especially Kirk. I don't know how far this would have gotten without your knowledge of these sets, not to mention the wealth of paperwork and service literature you so kindly sent me.

The pictures speak for themselves! Taken off air with nothing but a piece of 24" wire.

[kbmuri]

Jordan -

A+.

- Kirk

[MRX37]

Originally Posted by MRX37

Glad you got the old beast up and limping. Hopefully with the right tubes and some tweaking, you can make that thing strut!

Looks like I was right. Good job in bringing it back from the dead.

Is it your camera or the TV itself that makes the pictures on the screen look so low res, and show the scanlines so visibly?

[KentTeffeteller]

Hi,

Looking nice! Capeharts aren't too common either. Great job and you surely got quite an education on troubleshooting tough dog trouble.

[Tony V]

Fantastic job Jordan!

[freakaftr8]

Sweet! That set looks great! Congrats!

[kbmuri]

Is it your camera or the TV itself that makes the pictures on the screen look so low res, and show the scanlines so visibly?

Jordan's digital camera is too fast. My camera's "shutter speed" seems to be about 5 TV frames, so I get a smooth screen but sometimes I get a blur. Looks like Jordan's camera does a frame and a half, or so, so it catches the interlace on half the screen.

I trust his screen is "smooth as glass", in real life.

[jpdylon]

Yes, i speed up the shutter --otherwise I get a blur. I think its at 1/30 so I'm only capturing 1/2 frame. The focus is razor sharp.

The only occasional trouble the set has is on pictures that have bright scenes it will bend and jump vertically. The AGC control makes no difference, so I assume that its a sync separator or video issue

[MRX37]

Originally Posted by jpdylon

Yes, i speed up the shutter --otherwise I get a blur. I think its at 1/30 so I'm only capturing 1/2 frame. The focus is razor sharp.

That would explain it. Interlacing is one gripe I have against the NTSC standard, and for the life of me I can't figure out why they would add interlacing to the digital video standards. I know it was necessery for NTSC due to the technology at the time, but it's unneeded for HDTV.

Apart from the interlacing, which can't be helped anyway, the picture looks very very good for a 60 year old TV.

[kbmuri]

If you're taking signals straight off the air, the transmitted Vertical-Blanking Interval still has all that extra junk in it, maybe causing your occasional bending/jumping.