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Toshiba Rolling OSD

Toshiba model # CX21341 Chassis No. TAC 9117

Collapsed vertical, replaced vert ic AN5515 and the 2 brown 2.2uF 50wv C301, C305, both leaking oil and high esr. Pump up C308 100uF 35wv ok.

On power up full undistorted picture but top half shows spaced unblanked retrace lines. Looks like missing proper blanking?

The channel osd rolls up and down the right side about once per second. Could the big tv ic TA8680N be broken?

Need help, can't figure out what the broken vertical did to the osd or even if cause and effect.

A*s*i*m*o*v

... If all else fails, hurl it across the room a few times!

Reply to
Asimov
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Looks like you have missed some other bad caps bad pump up usually causes the IC failure. ESR those other caps..

kip

Reply to
kip

"kip" bravely wrote to "All" (28 Nov 05 16:22:13) --- on the heady topic of "Re: Toshiba Rolling OSD"

ki> Reply-To: "kip" ki> Xref: core-easynews sci.electronics.repair:349817

ki> Looks like you have missed some other bad caps ki> bad pump up usually causes the IC failure.

Agreed, usually the pump up causes the vert ic to fail. In this tv there were bad solders on the ic itself.

Just the 2 brown 2.2uF 50WV electros were bad.

BTW tried 220uF 35WV instead of the 100uF 35wv for the pump-up cap but no visible difference.

I might try 1uF instead of 2.2uF at the ramp generator though.

ki> ESR those other caps..

Checked ESR of electos around vert ic and derived supplies, also checked their values, and for gross leakage.

I was especially meticulous around the big tv IC with the low value

0.47uF electros but they were okay.

Also checked the QB20 digital transistor but it was switching ok. The SELECTOR ic also gets the vert pulse but it goes through QB20. How could its input be damaged and QB20 still be good? No way...

It really does seem like the vertical blanking pulse gate is missing somewhere.

A*s*i*m*o*v

... If all else fails, hurl it across the room a few times!

Reply to
Asimov

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