White Scan lines on top of toshiba 24AF44

[chrisbakr]

Hi, I am having trouble with small white lines at the top of my Toshiba 24af44 and have been told that it is probably a filter cap in the vertical deflection circuit? I do not have this problem when watching hd tv on letterbox, only when the commercials come on or the guide comes up. I would like to replace these capacitor/s myself, but do not know how to go about doing this or what to buy. I do have about 8 years doing desktop and laptop support so if someone would be able to help show me what to do I would appreciate it! thank you.

[Topcat]

Re: White Scan lines on top of toshiba 24AF44

turn the screen control on the FB down a little.

[chrisbakr]

Re: White Scan lines on top of toshiba 24AF44

Hi thank you, would you mind walking me through this or pointing me in the right direction for instructions? This is a new thing to me. thanks!

[Wizard]

Re: White Scan lines on top of toshiba 24AF44

Yes you have bad pump capacitor in vertical circuit. Replace it with 100uF 35V, standard ESR. No point in low ESR.

Cheers, Wizard

[chrisbakr]

Re: White Scan lines on top of toshiba 24AF44

ok i will buy the part, is there a site that will show me the spot on the board where i can locate the capacitor?

[Wizard]

Re: White Scan lines on top of toshiba 24AF44

Find the one diode with cathode end connected to the positive side of this small capacitor. This power goes through this diode on anode side and also to the vertical IC.
The capacitor is wired to the vertical IC that "stacks" both stored voltage of this cap plus supply power of vertical IC to around 48V or so for kicking beam up from bottom to top. Hence the pump capacitor.

Cheers, Wizard

[Topcat]

Re: White Scan lines on top of toshiba 24AF44

Yes you have bad pump capacitor in vertical circuit. Replace it with 100uF 35V, standard ESR. No point in low ESR.

Cheers, Wizard

Good call there......its been years since I've serviced CRT televisions, I'm very rusty!

[Wizard]

Re: White Scan lines on top of toshiba 24AF44

Oh I forgot, resolder the vertical IC and resolder the horizontal circuits for suspect solder joints.

Cheers, Wizard

[chrisbakr]

Re: White Scan lines on top of toshiba 24AF44

good deal, thank you! i will let yall know how it goes.

[Krankshaft]

Re: White Scan lines on top of toshiba 24AF44

Usually on borderline caps the lines will slowly migrate up as the cap heats up and the ESR goes down.

Screen voltage too high would wash out the picture in white and show lines all the way down the screen. I had the chance to mess with screen when replacing some flybacks .

Stupid Toshiba (sorry Orion) used 85C units Rubycon but still 85C on my set after repairing this vertical issue the SMD chroma IC toasted some more of these caps above it. There was a slight discoloring on the component side of the board above the IC to signify this.

It caused the TV to intermittently change channels. I'm betting these caps were in the micro controller circuit causing the TV to go wonky.

Hopefully you're more fortunate in this regard because I had to use my ESR meter to sniff all of these pests out. I mention this because your model number looks similar to mine.

Oh yes and get this cap business in the vertical circuit sorted out if left too long it can kill the vertical IC. As Wizard said general purpose is fine here but make sure its 105C rated.

[chrisbakr]

Re: White Scan lines on top of toshiba 24AF44

before i actually go in and start soldering though, this is what the picture looks like. Once i exit out of the guide and back to letterbox, the lines go away. [/IMG]

[Krankshaft]

Re: White Scan lines on top of toshiba 24AF44

This look familiar?

100uf 35V cap near the vertical IC.

My case wasn't as severe as yours it seems your cap is in worse shape.

[chrisbakr]

Re: White Scan lines on top of toshiba 24AF44

yep that's it! i have the caps on order so hopefully they'll get here in the next couple weeks.

[Wizard]

Re: White Scan lines on top of toshiba 24AF44

Yes, that is called vertical fold over.

Do it now as this is stressing out the vertical IC.

Cheers, Wizard

[chrisbakr]

Re: White Scan lines on top of toshiba 24AF44

ok I will, do you think it is alright to continue watching it until the parts come in? in letterbox where i do not see the lines?

[Wizard]

Re: White Scan lines on top of toshiba 24AF44

NO!

Cheers, Wizard