I have this small tv and hooked it up to the converter box and then connecting to the external port using a 3.5mm plug attached to the coaxial cable. When I push the plug all the way in, doesn't really work, if I touch the outside of the port with the tip of the plug, it works better.

Any suggestion on making a stronger attachment to the back?
Other way to attach plug?
Different kind of plug?

Thanks for looking and great site, glad I found it

the plug works much better on my Casio 970

Some of the older portable.sets had a 300 ohm balanced antenna mini jack vs the 75 ohm coax type your using. What you probably need is a 1/8" jack with 2 screw terminals labeled 300 ohm then a 300 ohm to 75 ohm antenna balun. I have such a set up I use for a couple of 60s Sony portable sets of mine.

Anothe morer kludgy option would be to plug the jack you have in then rig up something to connect only the center conductor of the coax to the outer barrel of your adapter.

Thanks for the response terminal. I was wondering if you can help me out? I am looking on amazon for the materials but I can't find the 1/8" jack with the two screws. All I see is the non solder type. Is there a better place to buy material for tv's electronics on the web outside of Amazon? lot of searching here, sorry do you have a picture of what yours might look like, my issue is the plug goes in but doesn't seem to get a proper contact. Looking online and having no luck!!!

I have this at home https://www.justdial.com/Quick-Push-On-Ohm-Matching-Transformer-Balun-75-300-Ohm-Off-Air-TV-Antenna-Balum-Coax-Cable-Female-Signal-Adapter/pid-89041060?search=Quick%20Push-On%20Ohm%20Matching%20Transformer%20Balun%2075-300%20Ohm%20Off-Air%20TV%20Antenna%20Balum%20Coax%20Cable%20Female %20Signal%20Adapter&catId=1000125&city=&nearme=0&sortby=pop&basedon=&show=false

and this I also have
https://picclick.com/2-UHF-VHF-FM-Plated-75-300-Ohm-AV-401161352893.html


Thanks
This is what I found? Looks the same as what I have now
https://www.amazon.com/CERRXIAN-Terminal-Headphone-Converter-Adapter/dp/B06Y5YJRPD/ref=sr_1_20?keywords=1%2F8%22+jack+with+two+screw+ terminals&qid=1579030621&sr=8-20


Is this what I am looking for?

https://www.ebay.com/itm/3-5mm-Balun-Plug-to-Screw-Terminal-Matching-Transformer-75-300-OHM-2Pcs/163820114187

The eBay link along with the second link is basically what I have (though I think my version of the eBay plug lacks the balun*). I got those parts from skycraft surplus in Orlando over a decade ago.
The last 3 links should give you what you need...If one 3.5mm ( or 1/8" when these were new) jack don't work, try the other. The Amazon jack with the second link balun should give 300 input.

* I'll see if I can find it and check when I get home tonight.

You know, I looked on amazon and they don't have that kind, I'll mess around with it and I was wondering, what does the black part of the plug do? Is that just a method built into the plug to make the fit tight? I used the same set up on my portable casio 970 2.3" and it works fine. I think the jack for the tv is a little too wide in diameter to make proper contact with the plug. I'll maybe figure out a way to connect to the outside. I love this tv, had one in 1980/81 and it was stolen from me at work.

I have a few other b/w tv's coming so I will see if I have the same problem

Thanks for helping.

By the way, I have a 1980 ONKYO stereo receiver, they don't look to be worth much

On the eBay one there is a balun built in to the black part....on this Amazon one the black part looks to be just a handle and wires straight to the terminals from the 1/8". .https://www.amazon.com/CERRXIAN-Terminal-Headphone-Converter-Adapter/dp/B06Y5YJRPD/ref=sr_1_20?keywords=1%2F8%22+jack+with+two+screw+ terminals&qid=1579030621&sr=8-20

Your first 2 links are 75 ohm to 300 ohm baluns (which are bidirectional usually ). Those baluns do 2 things: they match impedances between different impedance transmission lines, and they convert between BALanced and UNbalanced (hence the name) transmission line...

If the connector on the set isn't making contact with adapter then either the connectior on the set is non-standard, has dirty contacts, or damaged. You could spray contact cleaner, replace it, or if you plan to keep the plug plugged in to the set for years on end you could try placing a bit of aluminum foil between the plug and socket to shim it and make electrical contact...it ain't the most elegant solution but if it works good enough for you that is all that should matter.

Thanks Tom for the answer, I actually tried to wrap it around, what about if I built up some solder, let it dry, file down to a tight fit. Would that work the same way? I am new with any electronics work.

Thanks Tom for the answer, I actually tried to wrap it around, what about if I built up some solder, let it dry, file down to a tight fit. Would that work the same way? I am new with any electronics work.

The thing about soldering in there is, if your iron tip is actually small enough to fit, that if the body of the jack is plastic you can melt it faster than you can get a solder bead in there... I'd just change the jack on the TVs PCB at that point...if you want something original look for a junk monophonic cassette recorder from the period with a mic input jack and use solder wick or a solder sucker to remove the jack from the tape recorder PCB, then install on the TV.

I checked my adapter last night and it is identical to the eBay part.

Thanks Electronic, on the outside of the port it has a symbol of 75ohm I will try to attach picture, I decided to open up battery compartment, what?????? Batteries still in it!!!!!!!! Luckily only a little leakage on plastic sleave I wonder how old they are?

I might take the cover off and try to figure out why it only makes good contact to the tip of the connector. I like some of the other tv's that have the screw terminals on the outside. I tried the aluminum foil, no dice on that one.

Just searching, what about something from a radio that has an external port?

Those might be the original batteries it shipped with... I'd put them in a plastic container and keep them with the set.

Getting a better look at the connector on the side of the set it looks like Panasonic tried to make the connector proprietary... it looks like that plastic lip recesses such that the plug can't fully seat against the metal ring of the connector like it needs to inorder to make proper contact....also there appears to be a switch built into the top of the lip that would engage with a plastic connector that matches the inner profile of the lip. That switch probably switches between the internal ant and the jack...it may be hard to keep the set unmodified and use a non-original adapter. If you don't mind hacking the set you could probably grind the lip down with the dremmel and shim the switch up.

Here is a goofy trick you can use for sets that don't have an external ant jack. Radio Shack sells these small leads with alligator clips on each end. When I needed to test my Philco Safari I just took a clip lead and grabbed the antenna with one end and the center pin of the coax with the other.

If you have multiple portable sets and want to run many at once and not be tethered you could get an agile modulator and rig up a low power transmitter that covers just your property. I got a Blonder Tongue AM60 a few years ago and no longer tether my sets directly to signal sources. There's plenty of discussion of this here on VK if you run a search.

Good eye electronic, it does have that plastic lip and the only weird thing about that is the reason for this on an external port for an antenna. I had the TV when it came out in 1980 and it's a strange setup. That plastic piece is almost round but for a short piece. I do have those alligator clips and I might ground down the plastic in the back.

I bought a 2" Sony Watchman and it works perfectly with the same external antenna plug.

Thanks for helping out and the suggestions. I just wonder why they made a semi circular piece of plastic like that.

I just looked at the picture again, yeah it has that little piece of metal hanging down, but this is for an external antenna, crazy idea, I wonder what kind of jack was used?

Tom C is on the right track. That adapter is too fat to seat in.
Sony made one that was plastic & you could probably file it down
if need be.
This set is the ONLY one I have ever seen with a 75 ohm UHF input.
Normally its separate 300 ohm or one 75 ohm for both.

73 Zeno:smoke:
LFOD !

I might try to file down the 3.5mm and make it the same shape. Crazy design, I might just try to place a coax wire into it

You know, I looked at it again, that is just an optical illusion. It's the reflection of the 3.5mm. Crazy picture

Electronic,

What is this for, igot an extra digital to analog converter and this wire was in it?

Well, I decided to ground down the silver coaxial connector so it can fit in the back. Great picture now, thanks for helping.

Picture

Guess what, I broke off the brightness knob off the back after I didn't seat the case correctly, now I can't see the picture. Oh man this sucks

I really messed up on this one, I am so disappointed, wow had my favorite tv all set and I put the case back on and the knobs in the back, I forgot that they had to stick through the case. I disconnected case and I wiggled them a little bit and the one knob for brightness came off and I can't get it back on. These are the two pieces. I took an alligator clip and clamped the clip onto the board where the knob goes. It does then brighten the screen to make it viewable. Oh man I don't know what to do, so mad about this, killing me.


Suggestions?
Alternatives to this knob attachment. I do have a local tv repair guy but this thing I have no way to keep it attached. Oh man this is a big bummer, going to cry:tears::tears::tears::tears::tears::tears::tear s::tears::tears::tears:

Okay this is what I did, attached a bolt to squeeze the two pieces together but now no brightness adjustemnt

Okay this is what I did, attached a bolt to squeeze the two pieces together but now no brightness adjustemnt

Do you mean the brightness is now fixed at one point or there is no brightness?

If it's the former, you can probably fit a plastic washer (like for metal TO-220 transistors) and tighten the bolt/nut just enough to provide enough contact pressure but still allow adjustment.

If there's no picture, you might have cracked the wafer.

What's the value? I might have one somewhere.

John

Thanks John, I placed the bolt in there, tightened and now the picture is perfect. However, no adjustment for the brightness. I still have the turning knob for the back but not sure if I can ever attach again.

You can replace it with a trimmer pot of the same size & ohms.
Only thing is it will be a screw driver adjustment at that point but
it will work. These pots are delicate so dont blame yourself too much.
Lesson learned. Believe me over 40 years I broke a ton of things
from a 50 cent knob to a $300 CRT & got paid well to do it !

73 Zeno:smoke:
LFOD !

Do you know how I might get one of those? Trimmer pot, ohms?

Thanks

Do you know how I might get one of those? Trimmer pot, ohms?

Thanks

What's the value? I have some kicking around.

EDIT: The value is printed on the metal wiper. If it says (for instance), 102 it's a 2K. If it says 153 it's 150K, etc. The last digit being the multiplier. A 1 in the third place means multiply by 10, 2 in the third space means multiply by a hundred, a 3 means multiply by 1000 etc.

John

Brite control VR63 is a 500K ohms. OEM part ## is
EVLVOU15KB55 you never know you may find one.
If you can get a few from the same MFG you may be able to move the shaft over. Main thing is the ohms & a good physical fit, you can mouse it
to fit if need be.

73 Zeno:smoke:
LFOD !

Thanks guys for the assistance. I am not too sure about this stuff since I am a noob on fixing the tv's. However, it looks like fun and could I go to an electronic store for stuff?

Thanks guys for the assistance. I am not too sure about this stuff since I am a noob on fixing the tv's. However, it looks like fun and could I go to an electronic store for stuff?

Very few electronics stores carry potentiometers anymore. Radio Shack was probably the last big chain that sold that kind of stuff. There are some local surplus and old TV parts houses out there but it depends on where you are at...

Online is more likely to help. If the physical size of the pot is still common you might be able to source a new one from mouser or digikey... though figuring out how to correctly filter results to the best match with any reasonable efficiency is an art that could land you a purchasing job in industry, or qualify you as an engineering intern.

Any pot the same resistance and equal or higher wattage will electrically function...the closer the replacement is mechanically the more it will look and feel right to use.

Ultimately that is around a $1 part in a affordable obtainable 70s portable...If I broke one in one of my sets I'd shrug and see what I could pull out of my junk boxes.... some of us here my self included have 50s color sets where 1-10 examples are known to exist and another set of you can even find one costs a over a grand maybe even 10K....when you work on those putting a scratch or chip you can fix on something can ruin your day.

BTW: just saw your PM... my box is full so I can't send any PMs. Glad I've been able to help. I've been out of commission with the flu since Saturday night...

Thanks guys for the assistance. I am not too sure about this stuff since I am a noob on fixing the tv's. However, it looks like fun and could I go to an electronic store for stuff?

Give me a few days. There's a good chance I have one; just have to locate it...

:scratch2:

John

Thanks guys, I hope you feel better, crazy flu going around.