Replacing/repairing vacuum tube montitor

[entomophile]

I am trying to restore my TV Ping Pong cabinet.  The game works but the image is horizontally and vertically compressed.  The "monitor" is just a 19" black and white vacuum tube television.  I can 1) try to fix it, 2) pay someone to fix it, or 3) replace it.  So I have a few questions.  If it is too expensive to repair it, does the game lose any value if I replace the monitor?  Is there any way to take that video input and get it to work with a modern CRT or LCD computer monitor?  I'd like to at least get it hooked up to a known good monitor so I can make sure the game play is solid before I waste any time or money working on the television.  TIA, Greg

[Ken Layton]

In those old days, common television sets which only had an input for a tv antenna, were modified for video input. Many times the tv set's antenna connector was used as the video input "jack". The gameboards at the time all output standard NTSC composite video so any tv set or monitor with a video input jack can be used. Heck, you can even use security camera monitors too.

As to the problem with your original tube type monitor/tv set, it can have two problems: a bad tube and bad electrolytic capacitors. Back in those days tv set manufacturers tried to reduce costs by using the newly (then) designed tubes called "Compactrons" in which one tube could do several functions at once. This reduced the tube count and cost. What used to take a dozen tubes could now be handled by just 4 tubes.  If you know someone who has a tube tester (like a HAM radio operator or guitar amplifier repairman) I would suggest having the tubes tested first. It could be that simple as a bad/weak tube which you can replace yourself. Tubes can be purchased at www.tubesandmore.com

Keep in mind that these tv sets are now 40 years old and will also likely have some bad electrolytic capacitors needing to be replaced. The heat from the tubes tends to literally bake the capacitors.

If you need a service manual or schematic, copy down the make and model of the tv set and go here:

https://www.samswebsite.com/

Enter that information and the Howard W. Sams Company will likely have service literature you can buy for that tv set.

[entomophile]

Wow, thanks!  This set has 12 tubes.  I used to restore old radios so I can test the tubes.  So I am guessing the top paired wire going to VHF input are the video and ground signal and the bottom wire to the UHF input is probably audio?  The manual only tells what pin the wires go to on the circuit board but there is no schematic.  Any way to test these wires to figure it out without releasing the magic smoke?

[Ken Layton]

It would appear the top shielded cable is video going to the UHF terminals. Shield is ground (common) and the other wire is video.

The single wire on the VHF terminal is probably audio.

There is an easy way to find out which wire is what. Just disconnect one wire at a time and see what disappears, video or audio.

[entomophile]

Ah, of course.  So simple.  Thank you.

[Ken Layton]

Once you find out what wire does what, you should label the terminals for any future repairman.