Portable TV displaying whitescreen instead of static
 

Hi

I have a Sanyo portable CRT TV that is having a problem with it's display. When I turn this device on in the past it used to display static, but now only displays a white screen with a slight darkish area off center. Does anyone here know what might be the problem?

It's an old device so I thought a capacitor or something might have gone in it, however, I thought it best to ask here before I pull this thing apart to check to see if anything obvious is wrong on the inside.

https://i.imgur.com/kuzBrSJ.jpg?3

It could be that there is just too weak of atmospheric static for it to receive it. If you don't have or plan to get an analog RF video source for that set then any repair work or maintenance is gonna be a waste of effort.

If it has a video input it may be switched to that. Check the sides
& back for a switch. If not get a manual & get daring !

73 Zeno:smoke:
LFOD !

The blank white screen tells you that the CRT is getting High Voltage and sweep OK, but there is no actual video signal reaching it. The problem could be in the video amplifier circuit, video detector or even the IF amplifier circuits. Sometimes those circuits get power from a separate supply voltage than the rest so that might have failed.

LCD display looks dead too...

SR

Thank you for the responses,

Electronic M - I was planning to getting this thing going one way or another but that is on hold now. I don't think it weak atmospheric static, purely because it was working fine before and when I plug in a external antenna nothing changes.

Zeno - no video input I'm afraid only a external antenna port.

Notimetolooz - This sounds like the most likely thing, I'll look into it. Anything I should know before pulling this thing apart?

Boobtubeman - The LCD display is powered by a little button battery, it recently went flat, I haven't got around to picking up another one yet but will soon. I wonder if they 2 are related at all, maybe the TV won't work if that one is flat or something. Wish I had a manual.

There probably is, typically the newer stuff can have tricky to open cases.
I've never opened that one so I don't know. Obviously things are pretty tightly packed inside. Solid state parts can be easy to zap or otherwise damage. Also the parts can be harder to find replacements for than with tube equipment. It wouldn't seem to be the case but sometimes the solid state stuff used proprietary or at least uncommon parts.

These little sets can be surprisingly easy to work on.
When apart they look kinda stepped on. Just be careful not to
stress wires wires between assemblies & keep things from touching.
Depending on you knowledge level & your equipment it should
go OK. A service manual is the next step. Without one what you ( and I )
can do is very limited. Post the model number next & maybe someone
has it.

73 Zeno:smoke:
LFOD !

I had a quick look and managed to find the manual https://www.manualslib.com/manual/12...o-Tpm2170.html

My tools are multimeter and soldering iron, knowledge level is not great, but, I have to learn somehow.

I'm guessing my main area of focus will be the TV PCB, other than that any other parts that should warrant my attention?

You may have to keep looking for a manual, the manual at that link doesn't seem complete, no schematic of the TV section.
I can't tell how old that TV is. Normally anything I work on that is older than 1980 I replace all the electrolytic caps just for starters. That doesn't mean they don't go bad in anything newer.
You do not want to use a 100 watt soldering iron on something like this in general, 30- 40 watts is enough, with a fairly small tip. You didn't say what you have. A solder sucker of some sort is very handy. Without some type of signal generator you probably can't make many internal adjustments. An oscilloscope is very useful for TV work but you might luck out and not need it for this problem.