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Questions tagged [tv]

Use this tag for technical aspects of TV (video formats, for example). Shopping questions are off-topic and repair questions might be too localized.

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Understanding safety concerns with RGB modding hot-chassis TV

I'm in the US. I'd like clarifications on the safety of RGB modding an old, hot-chassis TV. I know it's not economically viable but I'd like to learn. While researching how to do this safely I ...
lwiseman's user avatar
  • 103
7 votes
4 answers
429 views

CRT vertical deflection problem

I'm getting an odd CRT problem. When cold, the tube has an area about 1/3 way down that isn't scanned. The area above is compressed and the area below a little stretched. I've attached 2 pictures - ...
squelch41's user avatar
  • 133
3 votes
1 answer
223 views

Can I use ceramics instead of electrolytic capacitors in CRT drive circuit?

I've been recapping an Amstrad PCW 9256 computer. All the electrotyics are bad on the analogue board - I've replaced the electrolytics I have in stock and the CRT is now working almost perfectly but ...
squelch41's user avatar
  • 133
0 votes
0 answers
16 views

Adding an Additional Power Source for the LED Strip Connected to the Television

I want to turn on a long LED strip when the TV is turned on. I thought of doing this using the TV's USB port. The problem is that the voltage from the TV's USB port is very low and cannot support such ...
Yoni's user avatar
  • 101
0 votes
2 answers
91 views

ON TV Decoder Magazine Article/Circuit?

Starting in the 1970s, there was a scrambled TV service transmitted over the air called "ON TV" in our region. I think "Radio Electronics" magazine published an article about ...
kackle123's user avatar
  • 305
3 votes
2 answers
160 views

Salvaging/splitting up some backlight LED strips to make a lightbox

I'm trying to reuse some old HD425Y1U51-T0L6 LED Backlight LED strips to make a light box. They look like this: The closest link I found for them (but no spec sheet) is https://www.shopjimmy.com/...
Rick T's user avatar
  • 205
0 votes
2 answers
111 views

How were high voltage vacuum triodes used in TVs?

How were the grids of TV high voltage (over 10 kilovolt) vacuum triodes operated back in the day?
Hermolaou's user avatar
1 vote
2 answers
640 views

TV motherboard / LDVS and universal LED panel

On eBay you can find hundreds of Samsung (but also LG, Philips, etc.) Smart TV motherboards (see e.g. here https://www.ebay.com/itm/132373029756). What I would like is to have more of those ...
STeN's user avatar
  • 11
0 votes
1 answer
769 views

Can a CRT last 100,000 hours or even 300,000?

Online, I could find that high-quality cathode-ray-tube displays (whether be it for a computer monitor or a television set) have a design lifespan of 30,000-50,000 hours of cumulative operation. I ...
CoastCity Lapse 00crashtest's user avatar
0 votes
1 answer
73 views

How to reuse analog TV - small Sony in particular [closed]

SOLVED SOLVED SOLVED SOLVED Min of 30 characters required
Jan Hus's user avatar
  • 101
1 vote
2 answers
365 views

HDMI CEC connections and ground reference

I'm trying to work with the HDMI-CEC bus and a STM32 microcontroller (currently on a Nucleo-144 board). I'm connecting a cut HDMI cable with some Dupont wires soldered on it, to interface to the ...
BDeliers's user avatar
8 votes
3 answers
3k views

Why do CRT TVs need a HSYNC pulse in signal?

Could someone, please, explain how old CRT TVs reacted to input signal, specifically to VSYNC and HSYNC pulses? Do these pulses control the electron beam? For instance, if signal would consist only of ...
Scylurus's user avatar
  • 107
1 vote
0 answers
52 views

Television repair - connectors and standards for display panel and controller boards

All my experience comes from 2 flat TVs, so my knowledge is quite reduced and questions have to be quite broad. Questions: Are there standards or common practices from manufactures about connections ...
Daniel Perez's user avatar
1 vote
0 answers
103 views

Raspberry pi inside CRT TV - piggyback off a 220v line on a TV main board?

I would like to mount a Raspberry Pi device inside an old CRT TV (yes, I am well aware of CRT safety protocols, I've been restoring them for a few years now). The Raspberry Pi is powered using 5 volts ...
stcojo's user avatar
  • 11
0 votes
0 answers
105 views

IR frequency counter

I want to deign a frequency counter in this way: A specific frequency (33 kHz) is radiated by an infrared transmitter from a distance of 10 m to the infrared receiver for 100 ms. After amplifying the ...
Hossein Ameri's user avatar
1 vote
3 answers
1k views

Could I use an RF modulator to broadcast signals from a Raspberry Pi to an analog tv over the air without the use of a coaxial cable?

"Long" story, but I connected a digital-to-analog converter (for OTA TV) to my mom's 1984 Samsung CRT, and now I'm wondering, could I broadcast (on low power, of course) HDMI outputs to a TV ...
William Hunter's user avatar
1 vote
1 answer
589 views

TV tuner pinout

I was looking for some old VHF/UHF TV tuners for an RF receiver experiment and stumbled upon this old tuner from a shop. It has a label showing TELE1-030A and an IC inside shows ALP008M (Terrestrial ...
user132257's user avatar
0 votes
1 answer
1k views

TV backlight LED strip doesn't work, but individual LEDs work fine

There are 9 LEDs (3 V each) connected in series in the LED strip. I tested individual LED with 3 V applied across, and it works fine, but when 9 × 3 V is applied across the whole strip, the LEDs are ...
Allen King's user avatar
-2 votes
1 answer
235 views

What is a circuit I could use to generate valid analog TV signal?

What is the simplest valid analog TV signal and what circuit is required to generate it?
John Palermo's user avatar
0 votes
1 answer
173 views

How were the phosphors applied to the inside glass tube of older colour CRTs?

I've been reading into how CRTs were assembled and how they work, but I can't seem to find any concise information behind how the coloured phosphors inside the inner glass tube were applied. There is ...
Reggie The Veggie's user avatar
0 votes
1 answer
94 views

TV Hisense HLE4815RT not tuning cable signal

I have a Hisense TV HLE4815RT (mainboard: RSAG7.820.5649), that suddenly stopped tuning cable signal, it just says "No signal". I tried different cables, removing some splitter, ...
Mark's user avatar
  • 117
4 votes
3 answers
589 views

DVB reception: Why do I need to add a coaxial cable to my installation to improve SNR of the signal?

I have the following installation: Dipole antenna <------> Coaxial cable (3 m) <-----> DVB receiver If I connect my dipole antenna directly to the DVB receiver, removing the coaxial cable (...
Mathieu Tournier's user avatar
-3 votes
2 answers
2k views

Can coaxial TV aerial cables be flat/ribbon? To go under thick rug for TV opposite aerial socket

A round shaped one would cause a ridge in the carpet. I already have setup a flat ethernet cable under the rug for similar scenario whereby device is opposite ethernet socket. Update it's to carry DVB-...
therobyouknow's user avatar
0 votes
1 answer
671 views

My speaker connected to my TV is making weird noises only when playing videos [closed]

Apologies if this is the incorrect forum, if anyone knows of a better forum to ask on I would appreciate the redirection. I have a very specific issue regarding audio playback from my TV. I have a ...
Naudé Conradie's user avatar
0 votes
1 answer
86 views

Reduce audio signal from TV when volume exceeds a certain level

I hate how loud action scenes are in movies, compared to how low the talking parts are. My TV is currently connecting to some speakers with a jackstick. Is it possible to measure the volume with ...
jonas's user avatar
  • 309
0 votes
1 answer
156 views

How to switch off the CATV signal on a splitter port

I'm trying to create some automation of switching off the CATV signal on a splitter port. Using a regular 5V Arduino relay module I've tried to interrupt the wire from the center of the coaxial cable ...
Mne's user avatar
  • 1
0 votes
1 answer
85 views

Defective Transformer Replacement

I've been working on repairing a TV psu, and discovered that the transformer in it is faulty (reading O.L. on every combination of pins except for diagonal in ohms mode on the DMM) I've been looking ...
Koen Van Den Elsen's user avatar
0 votes
2 answers
260 views

Fixing composite video distortion caused by brightness changes

I'm modifying an old CRT to take NTSC composite input (it only accepts RF over coax.) I have got a good signal going in but it has this weird distortion going on. When the image is dark the pixels may ...
gonjona's user avatar
0 votes
0 answers
475 views

How to convert composite AV signal or RGB to luma (grayscale)?

As the title says- how can you convert composite signal into luma?? As we all know, composite is just what it says, composite video with grayscale and color signal combined and luma is just grayscale. ...
user3161354's user avatar
0 votes
1 answer
62 views

What is 'mis-registration' and 'mis-collimation' of television signals?

I was reading about early televisions and television cameras, and I came across these terms with no explanation.... They appear on Google on a few pages, but again I cannot find a definition....
Kurt Hikes's user avatar
0 votes
5 answers
1k views

what do the colours of the wires on stereo speakers signify from old TVs and laptops? [closed]

I have a few laptop and a TV stereo speakers salvaged from old electronics in my possession and I have noticed a pattern that I cannot understand. Both the left and right of these speakers have two ...
yusufa22's user avatar
2 votes
0 answers
73 views

Why does changing CRT to HDTV lose antenna channels? [closed]

We have an internal antenna that is connected to a tiny CRT TV through a digital converter box. I recently replaced this CRT TV with an HDTV, and I removed the digital converter box since the HDTV ...
toothandsticks's user avatar
1 vote
0 answers
456 views

Replacing a 6 V LED backlight with two 3 V LED backlights

I have a 65" TCL TV which have backlight problem and I have another 60" TCL TV with broken screen. Now when I opened both TV to swap with LED backlighting strips, and I and I noticed the 60&...
Singh's user avatar
  • 11
0 votes
1 answer
103 views

Why my television provider doesn't measure the coaxial cable length?

I recently put cable TV in my room (we already had cable TV before, but not in my room). The technician from my TV provider, through a split, ran a coaxial cable up to the TV in my room. When he did ...
Rodrigo Pozo's user avatar
0 votes
1 answer
547 views

Meaning of TV Backlight LED strip details

I am learning electronics and I just disassembled a broken TV with the purpose of reconverting it into a smart light lamp. The issue is that I don't understand the details of the backlight LED strips. ...
oxmanroman's user avatar
0 votes
2 answers
410 views

troubles getting serial port tv to work

i recently posted a question, but didn't had an answer (my fault :) ). my question wasn't straight-forward and clear. so my final goal is to communicate between nodered (raspberry-pi) and my lg tv. I'...
madness007's user avatar
1 vote
0 answers
327 views

How to get static on CRT screen instead of black screen?

The TV in question is a Sony Trinitron KV-14M1D CRT. I know it sounds backwards but I need the screen to show white noise for a project (oscillograph); but there seems to be a static block that ...
Zaxarrrr's user avatar
1 vote
0 answers
1k views

Why don't LG RS232 commands work when the TV is on (only responds when off)?

I'm writing a new question after stumbling across this question which appeared to have similar symptoms: LG RS232 Commands partially working. As the other question noted, the power on command ...
tgpaul's user avatar
  • 49
0 votes
3 answers
467 views

Old tvs, how did storing settings work, and what changed in the tv when we tuned a channel?

I don't have an EE background, but I would like to understand some aspects of old TVs. When we tuned channel what exactly changed inside the tv. Was there a circuit card in the tv where something ...
user394334's user avatar
23 votes
7 answers
6k views

How did old television screens with a light grey phosphor create the darker contrast parts of the display?

Many old television screens have a very prominent "light grey" color to the glass, I'm guessing from the phosphor, create darker areas if the effect of electrons make the phosphor glow? Is ...
Zhro's user avatar
  • 2,885
0 votes
0 answers
158 views

How to test TV LED backlight failure [duplicate]

I recently picked up a Braum (Aldi) TV from the nature strip to play around with. The TV seems to work perfectly fine (Channels, DVD input, sound etc) except that there's no working backlight. I've ...
Mr G's user avatar
  • 113
7 votes
2 answers
1k views

"shark teeth"-like PCB feature in high voltage section of modern HDTV

I found this tooth-like non-masked, solder-covered trace pattern on modern single board HDTV. It's in the 120VAC "HOT" section of the switch-mode PS. Looks like some sort of spark gap or ...
Christopher Allen's user avatar
1 vote
1 answer
728 views

How to adjust picture geometry of a CRT TV?

I have a HD CRT TV (Silva Schneider 26 inch) which failed recently. So I took apart a working CRT TV (Philips L01-2E AA, 20 inch) and took its mainboard and connected it properly to the HD CRT tube. ...
MultiMdave's user avatar
0 votes
1 answer
459 views

Which components should be checked on a faulty tv power supply? [closed]

So, I'm new to working with electronics and I didn't study electrical engineering or anything related. I've collected some dead tvs and monitors over time hoping that I'm gonna fix them. I managed to ...
Emil-Sorin Malai's user avatar
0 votes
1 answer
705 views

Very old dual coaxial TV outlet, how to fix it to connect to a modern TV? [closed]

i've recently moved into an older updated apartment building and want to connect to the TV outlet but have a connection that i've never seen before. Can someone point me in the right direction of how ...
meak21's user avatar
  • 21
1 vote
3 answers
101 views

Light coming from the room influencing TV

Inside the TV Remote we have a LED of infrared light which sends commands to the TV. Isn't it influenced by the light of the room(if any?).I thought if an electron in the valence band absorbs a photon ...
ArtOfElectronics's user avatar
1 vote
4 answers
2k views

Why faulty, old CRT TV produce ozone

I have an old CRT TV which had to be switched ON for half an hour or so for the picture to stop being blurry and be 'viewable'. During this initial warm-up time there was a 'static' like noise coming ...
schizoid_man's user avatar
0 votes
2 answers
983 views

LED indicators intensity standards

I am trying to find any resources on the LED parameters (i.e. preferred intensity and luminosity ranges) that are used as indicators in various home appliances, such as Networked devices (i.e. routers)...
Łukasz Przeniosło's user avatar
2 votes
0 answers
823 views

How to ground a flyback transformer?

I designed a 50,000 volt power supply, that I am having problems with on grounding the HV side of the output. The HV appears to be injecting HV into my logic sections through the ground, damaging the ...
mike andrasko's user avatar
0 votes
1 answer
1k views

Ratio of colors to produce white in color television

If you consult pretty much any book on the theory of color television, it says that because the human eye is more sensitive to green than red or blue, the reference white for color television has been ...
dgwp's user avatar
  • 101