Videokarma.org

Go Back   Videokarma.org TV - Video - Vintage Television & Radio Forums > Vintage TV & Radio Tech Forum

We appreciate your help

in keeping this site going.
Reply
 
Thread Tools Display Modes
  #1  
Old 11-02-2018, 05:59 AM
yekwart yekwart is offline
VideoKarma Member
 
Join Date: Jul 2018
Posts: 6
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.

Reply With Quote
  #2  
Old 11-02-2018, 08:10 AM
Electronic M's Avatar
Electronic M Electronic M is offline
M is for Memory
 
Join Date: Jan 2011
Location: Pewaukee/Delafield Wi
Posts: 14,758
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.
__________________
Tom C.

Zenith: The quality stays in EVEN after the name falls off!
What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4
Reply With Quote
  #3  
Old 11-02-2018, 09:27 AM
zeno's Avatar
zeno zeno is offline
VideoKarma Member
 
Join Date: Mar 2013
Location: New Hampshire
Posts: 4,672
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
LFOD !
Reply With Quote
  #4  
Old 11-02-2018, 12:08 PM
Notimetolooz's Avatar
Notimetolooz Notimetolooz is offline
VideoKarma Member
 
Join Date: Mar 2014
Location: Dallas, TX
Posts: 547
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.
Reply With Quote
  #5  
Old 11-02-2018, 08:26 PM
Boobtubeman's Avatar
Boobtubeman Boobtubeman is offline
<---WANTED: Motorola 17P6
 
Join Date: Jun 2007
Location: Woodland Ca.
Posts: 931
LCD display looks dead too...

SR
Reply With Quote
Audiokarma
  #6  
Old 11-03-2018, 03:51 AM
yekwart yekwart is offline
VideoKarma Member
 
Join Date: Jul 2018
Posts: 6
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.
Reply With Quote
  #7  
Old 11-03-2018, 12:00 PM
Notimetolooz's Avatar
Notimetolooz Notimetolooz is offline
VideoKarma Member
 
Join Date: Mar 2014
Location: Dallas, TX
Posts: 547
Quote:
Originally Posted by yekwart View Post
Thank you for the responses,

Notimetolooz - This sounds like the most likely thing, I'll look into it. Anything I should know before pulling this thing apart?
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.
Reply With Quote
  #8  
Old 11-03-2018, 03:42 PM
zeno's Avatar
zeno zeno is offline
VideoKarma Member
 
Join Date: Mar 2013
Location: New Hampshire
Posts: 4,672
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
LFOD !
Reply With Quote
  #9  
Old 11-03-2018, 06:14 PM
yekwart yekwart is offline
VideoKarma Member
 
Join Date: Jul 2018
Posts: 6
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?
Reply With Quote
  #10  
Old 11-05-2018, 11:46 AM
Notimetolooz's Avatar
Notimetolooz Notimetolooz is offline
VideoKarma Member
 
Join Date: Mar 2014
Location: Dallas, TX
Posts: 547
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.
Reply With Quote
Audiokarma
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 02:41 PM.



Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
©Copyright 2012 VideoKarma.org, All rights reserved.