View Full Version : Vertical Line - Raytheon Porthole 1602


cwmoser
08-28-2016, 09:32 AM
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
08-28-2016, 01:31 PM
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
08-28-2016, 03:50 PM
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
08-28-2016, 10:41 PM
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
08-29-2016, 09:54 AM
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
08-29-2016, 10:07 AM
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
08-29-2016, 12:38 PM
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
09-02-2016, 08:18 AM
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
09-02-2016, 09:56 AM
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
09-02-2016, 02:58 PM
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
09-06-2016, 11:28 PM
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
09-07-2016, 08:02 AM
...
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
09-09-2016, 06:06 PM
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
09-09-2016, 06:15 PM
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
09-09-2016, 06:59 PM
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.

Electronic M
09-10-2016, 12:04 AM
VA62s are not exactly proper alignment equipment either...In the conventional sense. Supposedly there are ways of aligning and psuedo-aligning with one, but I have not heard a convincing explanation or seen a good demonstration.

cwmoser
09-10-2016, 06:58 AM
How are these older Televisions that use the old IF frequencies aligned using the test equipment we have today?

Electronic M
09-10-2016, 08:29 AM
Some of the newer (SS) Sweep marker generators had provisions for the older IF frequencies. You either find newer gear that works or fix older gear. Alignment generally consisted of setting up sweep/marker injection somewhere around the tuner, and placing a demodulator probe connected to the scope vertical channel near the detector stage. The scope H channel would be connected to the sweep generator sweep rate signal. You would get a band-pass response curve on the scope. You would switch on markers of specific frequencies to adjust traps and to see if peaks, valleys etc were in the right places, and tweak slugs to move them and shape the curve to meet the spec...Each set's service literature should contain detailed instructions outlining the procedure and response curve desired.

I've never done TV alignment, but I know that video IF alignment is supposed to be a substantial chore....I've got some sets that need an alignment, and have been collecting gear in preparation, but I need to check the calibration of my gear, read up on the procedure, and find a set I don't care about to practice on before I seriously get into doing full alignments.

Kevin Kuehn
09-11-2016, 12:50 AM
If you want to learn TV sweep alignment it's best to get some old servicing text books, or a sweep alignment generator operators manual that explains the process. But before go there you need to have a fairly solid understanding of how the video and audio signals travel through the various circuits. Without that basic understanding you're really at a loss as to how the equipment gets connected into circuit and what you're actually looking at on the scope display.

I had TV servicing classes back in the early 1980's and I don't recall us ever doing video IF alignment. I do recall our textbook for that class had an endorsement on the Sencor visual alignment process, but it never went into any detail on a practical way to utilize it. Even the manual for those units seems to tip toe around that specific application. IMO those units are more less a bells and whistles version of a video test pattern(to see what the video IF response of the set in question looks like), but not so friendly when it comes to adjusting the video response curve.