I totally applaud your rant about short versus open circuit. I recall the day I realized I was no longer able to hear high voltage powering up. I felt the same way. Todah!
This exact model NEC was seen in the movie WarGames. It's in the scene where Matthew Broderick's character is in the local library trying to get info on Dr. Falken. He's getting a chronologic printout of info and the display is sitting right there.
you should of taken that transistor out and put it back in no one would have noticed it was running before lol as a 72 year old its just great to watch this channel i have restored a few old tube radios been tinkering all my life
Character displays were typically used for text. They were designed to display the same thing for long periods without burning the image on the screen. Likely used for as an output for a terminal or POS system. I always look forward to you videos.
I repaired an old Panasonic inline gun tube (trinatron clone) about 30 years ago. It had a hor output transistor short, taking out a power resistor and the flyback transformer. I replaced all of those parts, and got the set working, but had to realign the conversion. That set was good for another 25+ years!
I gave a thumbs up because you never fail to entertain. Even when you/we repair working sets. The thing I wonder about is how long did it take to find out it was working?
Character Display = Monchrome Computer Monitor. They were commonly used for text display for computers in the late 70s and early 80s. I have that exact monitor, but my is branded Hewlett Packard. It is the matching monitor for my Hewlett Packard 86B computer from 1982 or so.
I also remembered you working on this, but I wasn't sure till you mentioned it. Regarding those orange wires, most probably the traces couldn't take the current in that part of the circuit.
I imagined that meter was toast after measuring the line output collector! But HP still made bombproof kit back in the day, those bench dmm still fetch ££££ even today.
Damn Shango I wish you had been my neighbor, teach me a thing or two about repairing electronics. It really is an art. Now they don't teach you shit about repairing Electronics, even in an Electronics Engineering degree.
My electronics teacher was pretty supportive of my repair attempts in college. He allowed me to go from having one half of one desk for my workspace, to two full desks covered in projects. Nearly everything that crossed my bench was working better after I got done with it.
So good at fixing TV's that he traveled back in time and already fixed this one! I'm de-stinking my little character display that's about the same size as this one. It smelled like the house it came out of so after I found there was no HV (similar problem, isn't that funny?) into the dilute vinegar bath it went! Not really worried about what the water soap and vinegar will do to some parts. Couldn't be any worse than the decaying environment it and others were found in was doing.
I like this kinda videos, too ! The h-frequent AC On the collektor is only about 10 times higher as the DC-supply, not more than 120V, this will not cremate most of meters (?) The danger of this is more likely on a 130V-supplied set with BU205...508.., then you have about 1,1 kV... There are 2 possibilities to destroy the H-output-Transistor: excessive Voltage or Current. The overcurrent-problem can be provided with an additional serial resistor of about 10...20 Ohms in a 12V-set and 120...200 Ohms in a bigger set with 130...V supply, this will prevent to much current caused by C-shorts in the deflection circuit or shorted HV-transformer or sth else. The excessive voltage is more difficult to prevent, thats why it is useful to test the flyback-capacitor of 6...12nF (130V supplied H-stages) and 60...100nF in 12V-stages. These are parallel to the C-E-connections, sometimes parted/devided (OW-correction circuits).
Thanks! I'm going to look into that at some point. Maybe Shango will take a shot at using the Sencore TVA-92 to drive the horizontal output on a few solid state sets. I've never tried mine. Maybe I should? I don't have much experience with repair.
@@johnnytacokleinschmidt515 Thanx für your answer, too, ist quite difficult to drive an Horizontal-output stage with trasnsitor switch, these have low current-amplification (h21e = B) of around 10, that means, it takes over 1 Amp to switch the transistor on in a right way (saturation), in 12V sets (10...13cm-tubes) as well as in 130...140V-stages (50...67cm). I forgot to mention, false driving is the 3rd possibility to destroy an H-output-Transistor. The timing has to be correct, the driving-current during "on" and the time between switching on to off has to be short to minimize the thermal loss in the transistor. Sometimes the base-region has to be actively "clean out" with a negative base-current, thats why driving-transformers with their inductance are useful for this. If you want to experiment with this, I would do this with a proper serial resistor in the supply and it is important to make sure, that the H-output-transistor is saturated in the "on"-Mode (Oscilloskop over C and E, U
On a typical solid state TV the AC input is rectified to a DC rail which is chopped into AC for the flyback and then rectified to form other rails. Not many times.
I had to laugh when you realized that you worked on that set before. What's worse, is when you have to do a bunch of pre-jigging just to start the testing--then realize you've been here before. In the past I have had multiple people that would say something like "Hey your the guy that fixed my (insert product) and it still working after multiple shops failed to fix it before you!"; and I will not have any memory of the set (and worse yet--for them) or any memory of them at all!! It gets worse when they can remember your name, and the shop conversation from years ago! And yes, you are really dumb for putting a lab-grade HP meter across the horizontal-output; just the wrong environment for that meter. The real reason is that yes, they are protected to a certain degree, but for that meter to have the high (usually 1000M-Ohm) input impedance and to also have relatively robust AC frequency response, the protections that can be applied are rather limited. So, you are gambling with a meter that has unique test-capabilities and not easy to replace (or repair). Glad you posted, as we've all suffered from Deja-Vu! 73...
It's a Character Display. That's why the screen was blank when the news was covering politicians.
Haha good one. Excellent diagnosis. Cause they have no character.🤣
I totally applaud your rant about short versus open circuit. I recall the day I realized I was no longer able to hear high voltage powering up. I felt the same way. Todah!
Wah wah wah zonk! :-/ life is catching up with me as well.
Wah wah wah zonk! I know the feeling. Life is catching up with me, too!
You know a UA-cam channel is honest when they will put out a video with mistakes. 👍Happy to be a subscriber.
I'm here for the great commentary. If i learn something about electronics that's gravy.
It also builds your, wait for it, Character.
@@chachavessel lol
Amazing repair. Fixed by removing a label!
Great rants, Shango. Always fun.
This exact model NEC was seen in the movie WarGames. It's in the scene where Matthew Broderick's character is in the local library trying to get info on Dr. Falken. He's getting a chronologic printout of info and the display is sitting right there.
Don't feel bad. I'm 48 and can't even remember what I ate for dinner 3 days ago.
I don’t remember what I ate for dinner 3 hours ago even.
Wait till you get to 55 you know you're halfway to retirement.
you should of taken that transistor out and put it back in no one would have noticed it was running before lol as a 72 year old its just great to watch this channel i have restored a few old tube radios been tinkering all my life
That thing would be right at home sitting on top of an Apple II computer.
I HAD one of these with my Apple computer!!
@@Runco990 I have one of these (branded Hewlett Packard) on my HP 86B computer.
Reminds me of playing Oregon Trail on an Apple 2 in elementary school.
I was good at that game
So the fastest way to fix one of these is to fix it earlier.
Buy a China made LCD for longevity
Character displays were typically used for text. They were designed to display the same thing for long periods without burning the image on the screen. Likely used for as an output for a terminal or POS system. I always look forward to you videos.
Preach it reverend shango. Providing an afterlife for all old tv’s
I repaired an old Panasonic inline gun tube (trinatron clone) about 30 years ago. It had a hor output transistor short, taking out a power resistor and the flyback transformer. I replaced all of those parts, and got the set working, but had to realign the conversion. That set was good for another 25+ years!
Take me to flavour country!
I gave a thumbs up because you never fail to entertain. Even when you/we repair working sets. The thing I wonder about is how long did it take to find out it was working?
Character Display = Monchrome Computer Monitor. They were commonly used for text display for computers in the late 70s and early 80s. I have that exact monitor, but my is branded Hewlett Packard. It is the matching monitor for my Hewlett Packard 86B computer from 1982 or so.
That's one of the reasons I record my videos, so I can rewatch them and teach myself how to do what I used to do :)
Where are the burning man videos or the 2 hour heist for vintage combo consoles with Chris and RTVPHN
Congratulations you join the club, enjoy your weekend, have a great day
I also remembered you working on this, but I wasn't sure till you mentioned it. Regarding those orange wires, most probably the traces couldn't take the current in that part of the circuit.
I imagined that meter was toast after measuring the line output collector! But HP still made bombproof kit back in the day, those bench dmm still fetch ££££ even today.
Oops, already fixed it, haha
Damn Shango I wish you had been my neighbor, teach me a thing or two about repairing electronics. It really is an art.
Now they don't teach you shit about repairing Electronics, even in an Electronics Engineering degree.
Disposables
My electronics teacher was pretty supportive of my repair attempts in college. He allowed me to go from having one half of one desk for my workspace, to two full desks covered in projects. Nearly everything that crossed my bench was working better after I got done with it.
Always good to see you are doing ok, you are allowed to make mistakes we all do!
We're old, and BAKED!
"Mr. Burns, your campaign seems to have the momentum of a runaway freight train. Why are you so popular?"
So good at fixing TV's that he traveled back in time and already fixed this one!
I'm de-stinking my little character display that's about the same size as this one. It smelled like the house it came out of so after I found there was no HV (similar problem, isn't that funny?) into the dilute vinegar bath it went! Not really worried about what the water soap and vinegar will do to some parts. Couldn't be any worse than the decaying environment it and others were found in was doing.
Not just going blind and deaf. Special mention of the dreaded CRS... Can't Remember Stuff ;-)
Great to see a Shango video and yes I learn something new everytime. I wait for my Saturday Morning Coffee with Shango Love this channel.
Shango time
I saves my weekend...thx for the vid.
Hi Shango and fans
Hey man how's it going
@@kevinkowalski5913 Doin good ,you too I hope
Still a good one, I watch religiously when you upload! And I did hear the horizontal oscillator/HV before you realized you had already fixed it 😢
Larger fuses will often indicate what components are adjacent to the original failed component .
Well done, again!!!
Did a few Dick Smith electronic kits here Oz . . the heart flutter when powered up mains . . one wrong solder & up in smoke
How intimate do I need to be with the electronics and how do I explain it to the doctor when they ask what happened? 😂😂
We all make mistakes at least you uploaded it 😂 still entertaining as always
I like this kinda videos, too ! The h-frequent AC On the collektor is only about 10 times higher as the DC-supply, not more than 120V, this will not cremate most of meters (?) The danger of this is more likely on a 130V-supplied set with BU205...508.., then you have about 1,1 kV... There are 2 possibilities to destroy the H-output-Transistor: excessive Voltage or Current. The overcurrent-problem can be provided with an additional serial resistor of about 10...20 Ohms in a 12V-set and 120...200 Ohms in a bigger set with 130...V supply, this will prevent to much current caused by C-shorts in the deflection circuit or shorted HV-transformer or sth else. The excessive voltage is more difficult to prevent, thats why it is useful to test the flyback-capacitor of 6...12nF (130V supplied H-stages) and 60...100nF in 12V-stages. These are parallel to the C-E-connections, sometimes parted/devided (OW-correction circuits).
Thanks! I'm going to look into that at some point. Maybe Shango will take a shot at using the Sencore TVA-92 to drive the horizontal output on a few solid state sets. I've never tried mine. Maybe I should? I don't have much experience with repair.
@@johnnytacokleinschmidt515 Thanx für your answer, too, ist quite difficult to drive an Horizontal-output stage with trasnsitor switch, these have low current-amplification (h21e = B) of around 10, that means, it takes over 1 Amp to switch the transistor on in a right way (saturation), in 12V sets (10...13cm-tubes) as well as in 130...140V-stages (50...67cm). I forgot to mention, false driving is the 3rd possibility to destroy an H-output-Transistor. The timing has to be correct, the driving-current during "on" and the time between switching on to off has to be short to minimize the thermal loss in the transistor. Sometimes the base-region has to be actively "clean out" with a negative base-current, thats why driving-transformers with their inductance are useful for this. If you want to experiment with this, I would do this with a proper serial resistor in the supply and it is important to make sure, that the H-output-transistor is saturated in the "on"-Mode (Oscilloskop over C and E, U
@@hql400 thanks again for your answer. These circuits are fascinating and daunting. I've never mastered them.
Blue tape and orange paper, - what more do you need "to convert" a monochrome display into a color one.
The power is coming up SHORT to the flickering hall light due to a intermittent OPEN. OR , the circuit Short of power is open when closed.
very Cool
Now I know that I can buy an HP 34401A multimeter and abuse it. Thanks! :)
Red power LED with green CRT, what were they thinking?
What kind of spikes are on the collector of the horizontal tranzistor that would cremate a normal meter?
Wow ok , This is all we had to drive industry and business with was these Green screens. Color screens didn't come out until quite a few years later.
Well you may be getting older. But at least your repairs are outlasting your memory now. 😊
10:40 Your baked!
That green screen colour suits well to politicians and journalists. They are all lizards.
character display.... i think that is why we all are watching this
In 93 $15.00 was enough gas to get me to work for the week.
I have the smaller version of that. I used to have that one too.
How many times does a TV NORMALLY change the voltage from AC to DC and possibly back by it's Circuitry Please?
On a typical solid state TV the AC input is rectified to a DC rail which is chopped into AC for the flyback and then rectified to form other rails. Not many times.
Ok, dumb question. If you fixed a customers set some time ago, why did you still have it? Seems like it should have gone home.
so this set had been fixed and was just sitting around? you said you should have peeled off the defect label.
The best repair, is no repair - to steal a line from Elon, "the best part is no part"
I like to fix things before I fix them cus it's faster.
1:57 Listen to wise advice
:D
I'm old and tired and done, too.
I believe nothing on that TV anymore
it's not easy being green
Jelly capacitor
BRAIN FART!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!-LMBO!!!!!!!!!!!!!!!!!
I broke my nec yesterday
I had to laugh when you realized that you worked on that set before. What's worse, is when you have to do a bunch of pre-jigging just to start the testing--then realize you've been here before.
In the past I have had multiple people that would say something like "Hey your the guy that fixed my (insert product) and it still working after multiple shops failed to fix it before you!"; and I will not have any memory of the set (and worse yet--for them) or any memory of them at all!! It gets worse when they can remember your name, and the shop conversation from years ago!
And yes, you are really dumb for putting a lab-grade HP meter across the horizontal-output; just the wrong environment for that meter.
The real reason is that yes, they are protected to a certain degree, but for that meter to have the high (usually 1000M-Ohm) input impedance and to also have relatively robust AC frequency response, the protections that can be applied are rather limited. So, you are gambling with a meter that has unique test-capabilities and not easy to replace (or repair).
Glad you posted, as we've all suffered from Deja-Vu! 73...
A certain high ranking politician has all these faults described going on at the same time
If it ain’t broke …