Vertical Line - Raytheon Porthole 1602

[cwmoser]

Installed a NOS 16AP4 CRT in my Raytheon Porthole 1602 Chassis 16AX23.
It tested strong with my CRT tester and has better contrast than my old 16AP4.
Been several years since I was active in restoring antique TVs.

The Video source is a Blonder Tongue modulator and a DVD player.
TV and modulator antenna not but about 20 feet apart.

Anyway, note the vertical line in the middle of the picture.
I do get some intermittant crackling in the Speaker even with the Audio
turned all the way down.
I did not tune the TV after I had recapped it.

Got any ideas on how I can improve the picture quality?

[reichsrundfu]

Looks like a horizontal drive issue. Check and adjust the Horizontal drive as much as you can I suspect you'll see the white line move towards the left and if you have enough range, disappear.

George

[Phil Nelson]

Yes, service manuals for old TVs often tell you to advance the horizontal drive control until such a white line appears, and then back it off just enough to make the line fade out.

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

[ohohyodafarted]

Some sets are also very touchy WRT the horizontal output tube. I have a CTC4 that it took subbing a handful of various HO tubes to find one that would eliminate the drive line. So if adjusting the H-drive doesn't do the trick for you, try subbing a bunch of different HO tubes. You just might find one that eliminates the drive line, where others did not.

[cwmoser]

Thanks for the heads up about the Horizontal Drive control.

What do you think is the reason for the sound interference that occurs
out of the Speaker even when the Volume Control has been turned all
the way down to minimum?

[Electronic M]

Try pulling the audio detector tube (assuming it is a parallel heater set*) and see if the interference goes away. If it stays it is in the audio amp (or it's power supply), if it is gone check the RF/IF system....Though I'd fix the horizontal issue causing the line first....A lot of power goes through the H output tube and if it is set up real wrong (such as in your pic) it is possible for the tube to generate an RF pulse strong enough to be picked up by the tuner and interfere with the picture and or sound.

[reichsrundfu]

I'm noting that with your audio you are describing intermittent "crackling". Not a constant buzz. I'd suggest swapping out the audio output tube and also make sure the socket contacts are good and clean. I had the same issue with my DuMont RA103 but found it was just the af output tube was on its way out. Fer sure, focus on your horizontal drive issue first. The audio should be a quick fix!

George

[cwmoser]

Substituted some tubes and adjusted the Blonder Tongue modulator levels and
got the crackling audio better ... but still have these issues:

- video is not that great - grainy - see photos
- following procedure in Riders TV manual #5, it says to adjust the station control
for maximum audio. Seems that maximum audio is not optimal video even when
I adjust the fine tuning.
- playing old B&W movies from DVD like Amos & Andy in the photos the video is
basically stable, but playing color video off of VCR tape is jerky. All content is
being transmitted using my Blonder Tongue modulators. My Zenith porthole does
not have this problem - and its farther away from the antennas.

[Electronic M]

If your VCR is not playing through a TBC you will get very different results from sets with different circuits. The sync timing of a VCR varies in ways that broadcasts of the time never did....TVs then were NOT designed to deal with it well, and those that do only do so by dumb luck...Every circuit of the time will handle it somewhat different. Some will be okay some terrible. DVD, and broadcast sources are the only signals where consistency of performance should be present.

[reichsrundfu]

Originally Posted by Electronic M

If your VCR is not playing through a TBC you will get very different results from sets with different circuits. The sync timing of a VCR varies in ways that broadcasts of the time never did....TVs then were NOT designed to deal with it well, and those that do only do so by dumb luck...Every circuit of the time will handle it somewhat different. Some will be okay some terrible. DVD, and broadcast sources are the only signals where consistency of performance should be present.

Quite agree here. Avoid Videotape at all costs. Stuck with DVD or cable / satellite
Input. Also I kinda suggest you forget about the Blonder Tongue modulator and just go direct hookup s CS you may be dealing with transmission issues with your unit and not with any fault in the tv. Go back to your modulator after your work is complete for the sake on sheer convenience.

Eliminate your variables as much as you can !

George

[Electronic M]

I never said, nor ever will I say to avoid video tape...You just have to do it right and or know what to expect. With a good tape, player and (sometimes) a TBC VHS will look as good or better than DVD on a vintage NTSC TV set...But at non-optimal it can look pretty bad.

Personally I consider LD to be the gold standard. Relatively affordable used today, and about as good and consistent quality as an analog format could be...It will blow the doors off VHS and DVD on a high-ish performance NTSC TV set.

Personally I prefer BT modulators...They can sometimes need a recap themselves/be temperamental, but when right they usually are stable and the best modulation scheme....Always test your modulators and have alternate sources. I like to keep a good 90's or later SS TV set or three around to test my sources.

[vts1134]

Originally Posted by Electronic M

...
Personally I prefer BT modulators...They can sometimes need a recap themselves/be temperamental, but when right they usually are stable and the best modulation scheme....Always test your modulators and have alternate sources. I like to keep a good 90's or later SS TV set or three around to test my sources.

I second that suggestion. I chased a problem for quite a while before I realized my modulator was at fault. Now I also keep a 90's television in my rack with the modulator to spot check the performance of my "broadcast" from time to time. I also was never able to get an antenna to work reliably with my modulator, consequently all of my sets are hardwired to the modulator.

[cwmoser]

I picked up a DVD player at a consignment shop.
TV plays a little better but the picture does seem grainy.

Riders TV Manual states that I should adjust the Channel Selector adjuster (individual
for each channel) for maximum Audio. When I do that the picture quality it not
the best. When I adjust the picture quality for best, the audio drops off markedly.

I'm wondering if this TV is in need of an alignment. Never adjusted the IF coils
in a TV. I have a modified B&K 1077B that might be able to put out the proper
IF frequency but I do not have the skill to do it properly. I'm tempted to make
some minor tweaks on it though.

Also, some DVDs play much better than others. For example my Amos & Andy
DVD set play better than the Red Skeleton set. Perhaps this TV is super sensitive
to modern signals.

I do get some intermittent crackling with the audio/video and suspect I might
have something else wrong - perhaps a bad tube somewhere.

[Electronic M]

A B&K 1077 is NOT for alignment, but is good for troubleshooting dead IF stages (among MANY other uses). To Do an alignment you need a properly calibrated sweep/marker generator that works with the IF frequency of your set (different sets used different frequencies), probes, and an oscilloscope.

If you can get good audio and good video but not at the same fine tuning point you may want to try 'walking' the sound IF over to line up with the video. To to that have it fine tuned to best video or (if there is no sound at that setting) between best video and sound, then adjust sound IF for best sound, and if not at best picture setting of fine tuning, fine tune closer and readjust sound IF.

[cwmoser]

Sorry, I've been away from Radio/TV restoration for about 3 years.
Instead of B&K 1077, its my Sencore VA62 that I modified. A fellow came
up with a replacement EPROM for it that expanded the IF frequencies so
that this instrument could be used with older televisions.
I got a lot of vintage test equipment that I have acquired but do not have
enough skill to really use properly. Wish Tech Schools still taught TV servicing.
Be a nice class to take to learn more about this hobby.

I'll soon pull the chassis in my Raytheon TV and take it to my test bench
and see if I can make some IF adjustments like you suggested.

I will say that my Zenith Porthole TV plays audio and video much better
than my Raytheon Porthole. Maybe its the circuit design as the circuitry
under the chassis does look much simpler than the Zenith.