Riddled TV Repair Forum
Service Menu and Manual Schematics
 
   
 FAQFAQ   SearchSearch   RegisterRegister 
   Log inLog in 
Toshiba 27A43C with thin white lines across top of screen   Goto page 1, 2  Next  
Post new topic   Reply to topic    Riddled TV Repair Forum Index -> TV Repair
 
Author Message
mrmza



Joined: 25 Jan 2011
Posts: 6
Location: Canada

PostPosted: Tue Jan 25, 2011 11:31 am    Post subject: Toshiba 27A43C with thin white lines across top of screen Reply with quote

I'm having the same issue with my Toshiba 27A43C as described in a post here:

http://www.riddledtv.com/forums/toshiba-mw24fp1-with-thin-white-lines-across-top-of-screen-t2170.html

Quote:
the problem is as follows: i have thin white lines going across my screen. sometimes it covers the top 5 inches of the tv and other times it covers less than one. sometimes it changes between channels and sometimes grows or shrinks out of nowhere.


Located at C427 is a 2200uF 35V capacitor. JTS1957 refers to a 100 uF 35V capacitor in the post above and I'm wondering if I'm looking at the right location for my model. If so, I'm assuming I can replace the 2,200 uF with the same value and have it fixed?[/quote]
Google

PostPost subject: Advertisement

JTS1957



Joined: 21 Jan 2009
Posts: 2341
Location: Far, Far Away

PostPosted: Tue Jan 25, 2011 12:41 pm    Post subject: Reply with quote

According to the schematics for each set, they BOTH use a C427 100ufd 35 volt electrolytic. I don't even see a 2200ufd in the vertical "deflection" circuit. I do see a C413 2200ufd 35 volt in the VCC line to the vertical output IC.
mrmza



Joined: 25 Jan 2011
Posts: 6
Location: Canada

PostPosted: Tue Jan 25, 2011 4:33 pm    Post subject: Reply with quote

I stand corrected, I was looking to the right. Thanks for the fast response JTS1957.

I've highlighted the capacitor from this photo I just took.


Unfortunately there is no polarity on this cap would you know how a polarized cap should be orientated. I'm assuming anode is closest to me from the photograph? Secondly, looking at what I have available here, I do have a polarized 100 uF 50V capacitor and I'm wondering would this work?

Otherwise, I'll find the one you suggested here:

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=P5551-ND
mrmza



Joined: 25 Jan 2011
Posts: 6
Location: Canada

PostPosted: Tue Jan 25, 2011 5:11 pm    Post subject: Reply with quote

I just discovered upon close inspection the C427 capacitor is marked "104 W".

From what i've seen online, 104 may indicate 0.10 uF (100 nF). Is this correct?
JTS1957



Joined: 21 Jan 2009
Posts: 2341
Location: Far, Far Away

PostPosted: Tue Jan 25, 2011 5:31 pm    Post subject: Reply with quote

My error (maybe I opened two copies of the other sets pdf). In your case, C407 is the 100ufd 35V (50 volt will work - NOTE polarity {"-"} stripe) cap. At IC401 end of heat sink.

Sorry about confusion.
Google

PostPost subject: Advertisement

mrmza



Joined: 25 Jan 2011
Posts: 6
Location: Canada

PostPosted: Tue Jan 25, 2011 5:56 pm    Post subject: Reply with quote

Thank you for the clarification! I'll attempt this project tomorrow.

Just wondering what your preferred method of discharging the board to work on.

When I opened it to just "take a look", I turned the TV off, unplugged it, on, it flashed, off, hit power again, nothing, off, then opened it up. Would that sufficiency drain it do you think? Or should I be using this method:

http://www.riddledtv.com/journal/DischargeCRT/
JTS1957



Joined: 21 Jan 2009
Posts: 2341
Location: Far, Far Away

PostPosted: Tue Jan 25, 2011 6:06 pm    Post subject: Reply with quote

Repair can be done with most things left connected. I usually take it only as far apart as I need to to accomplish repair.

I notice you did NOT have to unplug yoke to take your picture.

Only discharge CRT if you disconnect the whole board.
kuhurdler



Joined: 28 Dec 2006
Posts: 2862
Location: Overland Park, KS

PostPosted: Tue Jan 25, 2011 6:11 pm    Post subject: Reply with quote

My default response is to say that you might as well discharge it, because it's super easy, and it could save lives.

I sometimes don't always use my isolation transformer either, but the times that I get a jolt, I sure wish that I had.
JTS1957



Joined: 21 Jan 2009
Posts: 2341
Location: Far, Far Away

PostPosted: Tue Jan 25, 2011 6:47 pm    Post subject: Reply with quote

Bear in mind there is a bit of a difference between being zapped by a operating set ... and having a non-operating sets' CRT discharge ONCE through you.
mrmza



Joined: 25 Jan 2011
Posts: 6
Location: Canada

PostPosted: Wed Jan 26, 2011 2:03 pm    Post subject: Reply with quote

Just tackling the project now. I cannot see C407 so I'm going to have to pull the board.

Doing various probes, I discover C426 (250V 33uF) is sitting at 100 VDC. I felt it would be time to discharge the CRT as discussed. I connected one alligator clip to the "aquadag". (Two conductors extend from the yoke to this with a spring in the middle.) I slid a screw driver in to make contact under the red wires plug on the back of the screen and I could hear a very small spark. I continued to make contact a few times. I then measured C426 and it didn't discharge at all.

When i probe below the main board to that device the red wire from the screen connects to, (one location marked 180V) there is no voltage present.

I'm wondering if there should be something else I do, or am I just doing it wrong?
Display posts from previous:   
Post new topic   Reply to topic    Riddled TV Repair Forum Index -> TV Repair All times are GMT - 6 Hours
Goto page 1, 2  Next
Page 1 of 2

 


Disclaimer: All information provided by RiddledTV is strictly for information purposes only. Please observe all warnings displayed on your electronic
devices. This information should only be used to help diagnose work, and all service should be performed by a qualified technician.
Contact Us       Privacy Policy       Copyright © 2015 RiddledTV.com       Advertise on RiddedTV.com