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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Tue 02, 2017 12:09 pm 
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You're perseverance and effort is indeed to be applauded! Very impressive work for what at first seemed like a hopeless case!


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Tue 02, 2017 12:57 pm 
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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Tue 02, 2017 8:48 pm 
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One factor in the picture quality was the antenna wire to the TV. Moving it around greatly improved or degraded the picture. To remove that from the equation I soldered the converter directly to the antenna plug.
(note - the tubes are lit as you can see. What's My Line was playing on the Buzzr network.)


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Fri 05, 2017 4:18 pm 
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A more secure antenna connection on my Stromberg-Carlson DuMont RA-103 clone. Works well because DuMont used a 73 ohm lead to the Tuner:

Image

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Fri 05, 2017 4:34 pm 
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M3 - I've thought about having the coax run directly to the set. It would be more secure, and hopefully remote ALL distortion from antenna cable. How did you attach the other end of the coax to the tuner circuit? Also, do you know if it would work on my 48-1000? Below is the output I'm using to the set. The converter dongle in the photo is the one I've since attached directly to the antenna socket on the set. The coax running into that dongle comes out of the RF modulator. Is that able to run directly to the tuner circuit?


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Fri 05, 2017 5:03 pm 
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The coax was already present in the DuMont chassis. I just trimmed and attached a female screw-on connector on the end, then drilled an oversized hole in the mounting board, added a female to female extension to the coax, and secured it with a hex nut.

I don't know whether 75 ohm coax can be directly substituted for the old flat wire antenna. Perhaps others can chime in. Balun Connectors are used for a reason, I believe. 8)

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Fri 05, 2017 6:06 pm 
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Using twin lead can be tricky. To work correctly the twin lead needs to be kept at least 6 inches away from everything. And if it has to be closer to anything than that then each of the wires in the twin lead has to be exactly the same distance from things.

Looking at the schematic for your set, it looks like you might be able to run coax to the tuner. Try connecting the shield of the coax to the case of the tuner near where the twin lead attaches. Disconnect the twin lead and connect the center conductor to one of the terminals where the twin lead connected with the other one not connected to anything. See how that works. Try switching the center conductor to the other terminal and see if there is any difference. If everything is perfect there will be no difference.

That is all based on the schematic being correct when it shows that the antenna coupling coil has a grounded center tap.

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Fri 05, 2017 7:08 pm 
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The photos below show the internal antenna-to-tuner wiring. It is simply a piece of antenna wire going from the socket to the tuner circuit. Not any inches away from anything. The only reason I'm interested in maybe replacing this with coax all the way to the tuner, or do anything else electronically at this point, is to correct these symptoms:
- band of very light snow that slowly moves up the screen - moving the antenna wire around, and then connecting the dongle directly seemed to reduce this
- better configuration for all of the adjustments - my impression is that I've "tweaked" everything to get good performance, but that's left some of the controls "not in their mid range". I.e. it seems to me they're turned too far to one extreme or the other to make it all work. My thinking is that further twiddling with the internal adjustment - all those little screws - might let the user-facing controls be more centered.

To be clear - neither of these is fatal. I could watch the set forever as it is now and be very happy. But as a perfectionist that voice in my head won't shut up so I'm thinking how can I get rid of the snow? How can I better get the controls and adjustments all lined up? So I'm thinking about these things, but may not do them in the end if I opt for safety, rather than risk upsetting a good thing in search of something better. I'll let you know.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Fri 05, 2017 7:28 pm 
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sdyer wrote:
- band of very light snow that slowly moves up the screen - moving the antenna wire around, and then connecting the dongle directly seemed to reduce this
- better configuration for all of the adjustments - my impression is that I've "tweaked" everything to get good performance, but that's left some of the controls "not in their mid range". I.e. it seems to me they're turned too far to one extreme or the other to make it all work. My thinking is that further twiddling with the internal adjustment - all those little screws - might let the user-facing controls be more centered.

Don't touch those little screws. To adjust those you would need to have a sweep generator, a marker generator, an oscilloscope, and a great deal of patience and time.

The snow sounds like power line interference being picked up by your set. That sort of interference can be generated by almost anything in your house. Running coax directly to the tuner might help. That sounds like an experiment that you could easily do. You can always put the twin lead back if the coax does not help.

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Fri 05, 2017 8:07 pm 
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Hmm. Power line interference you say. Way back when I was starting to restore the electronics, someone here suggested I remove two mica caps on the power circuit. So I took out C100 and C101. I can't find the post (I did look for it) but the gist was that they don't have much benefit with modern, cleaner power but could cause problems if they're bad, so try taking them out. The photo below shows them in the schematic. Since then I've gotten the set running, to its current very-good-but-perhaps-not-as-perfect-as-it-could-be state.

Recently I attempted to put them, the original suitcases, back, thinking they might help with the snow issue. Something was haywire though and the GFI socket the set is plugged into (via a variac) kept tripping. So I abandoned the effort.

Do you think putting these back would help with the snow-band issue? If so are they directional or something? Any thoughts on why the GFI tripping?

Come to think of it this house was build in the early 50's, maybe it's power isn't so clean. But it's on a newly-installed circuit, that I had put in a few years ago for the workbenches. So it's not original power lines.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Fri 05, 2017 8:53 pm 
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Location: Woodinville, WA USA
I would install new line filter caps (not reuse the original caps). This article at justradios.com explains all about line filter ("safety") caps and how to replace them:

http://www.justradios.com/safetytips.html

Regards,

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Fri 05, 2017 9:12 pm 
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Those caps would really be paper caps in a case that looks something like mica caps. The originals are going to be quite leaky and they will often explode if left in. That is why you need to remove them. Sometimes you can get away without them. But I always put in new ones before I call a set done. For temporary use for testing you can use standard 600 volt caps. But you really should have safety cps for the final installation.

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Fri 05, 2017 9:57 pm 
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I checked my notes. On March 5 I jumpered in the original caps but noticed no real improvement with the set. I went ahead and soldered them in - they were there before, so what the heck. Then I got the GFI tripping. So I took them out and left them out, since I'd noticed no improvement.
I'm willing to try again, with new caps, to see if they make an improvement. Perhaps the originals (first pic below) are bad. Would these at just radios.com (second pic below) be the ones to order?


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safety cap for power line (maybe).jpeg
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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Sat 06, 2017 12:42 am 
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Yes, those are the right ones.

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Sat 06, 2017 6:36 pm 
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One of those line caps must be shorted if it caused a breaker trip. Like Tom mentions there's no reason you can't temporary tack a couple of the the yellow axial lead .01 @ 600v in as a test before special ordering the safety caps. Regarding your user controls not being centered - that has nothing to do with the RF/IF alignment adjustment screws. It's caused by passive component tolerances being too far out, but there's no guarantee they were centered when new. It could be some of your control elements have drifted up in value. Personally I'd leave well enough alone as long as the control allows normal operation.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Sun 07, 2017 7:16 pm 
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Just Radios has a $20 minimum. I found these on Mouser. But why are they over $5 each but Just Radios has them for 99 cents?


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Mon 08, 2017 4:21 pm 
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Probably because it is surface mount. Give this one a try - only $0.26 at Mouser.

http://www.mouser.com/ProductDetail/Vis ... bK3NPbs%3d


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Tue 09, 2017 5:37 pm 
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Kevin Kuehn wrote:
One of those line caps must be shorted if it caused a breaker trip. Like Tom mentions there's no reason you can't temporary tack a couple of the the yellow axial lead .01 @ 600v in as a test before special ordering the safety caps. Regarding your user controls not being centered - that has nothing to do with the RF/IF alignment adjustment screws. It's caused by passive component tolerances being too far out, but there's no guarantee they were centered when new. It could be some of your control elements have drifted up in value. Personally I'd leave well enough alone as long as the control allows normal operation.


+1
The only time to worry about a control's range is when it is only set to a usable setting at the extreme end of it's range.

I just won the only complete 48-1000 with a double-D CRT mask at the ETF swap meet so I'm going to be restoring one of these sets soon.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Wed 10, 2017 4:26 am 
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Electronic Memory - congratulations! It's a fun set to work on.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Sat 13, 2017 8:13 pm 
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So I have an older Apple TV and I thought I'd hook it up to the Philco. I got an HDMI to AV converter - below. At first the picture had heavy diagonal bands over it. Removing the copy-protection-elimination thing - the gray unit in the photo - cleared that up. Mostly. There are still faint, but visible, diagonal bands over the picture.
Do any of you know how to get proper input to a set like this from HDMI?

EDIT: I noticed that on other inputs the diagonal bands were there. Unplugging the Apple TV got rid of them. So something about the Apple TV - either it's effect on the power or its output - is affecting the TV, even when the RCA switch box is not set to the Apple TV. I'll investigate more later.


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