Vers
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May 19, 2005, 3:36 AM
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Adjust overscan on older 34" Toshiba CRT? (Solved)
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Trying to figure out how to adjust the overscan on an older Toshiba model CX34549 34" (84cm) CRT set. The tube has a very good picture for a 15 year old set, tainted with just a bit of faint vertical foldover and some dot crawl. Lots of work has been done inside, looks like most of the caps, vertical IC and jungle IC have been replaced. My concern is that there is a lot of overscan, about 20%.
I have lots of test equipment (scope, pattern gen, DMM, etc) but no schematic. Can do digital electronics in my sleep, but not a lot of TV bench time. The flyback board has the familar screen/focus pots, h. width, side pincushion and an unmarked pot, R450 (appears to be fine vertical height adjust). The CRT board has the blue & green drive, RGB bias and an unmarked three position switch, S201 (possible service mode switch?). The main board has R352 labelled as (vertical) "HEIGHT". This is the coarse vertical height adj, working after replacing a cracked pot. Also a master level adjustment, labelled "SUB BRI" & three unmarked pots near the jungle IC and a few pots on the audio board. Will replace the vertical caps and C301/305/308 in case they are leaky, but don't expect it to change the overscan.
Can't seem to get into an OSD service mode. There is no menu button on the TV & going press mute, press & hold mute, adj. doesn't do anything. The alternate method.. volume to zero, volume down, then "9" gets a "F" symbol in the lower right corner for a few seconds, but no "S" indicator or apparent menu items. Not sure if F might refer to factory (service mode) or perhaps F as in F59 (coax input).
I'm kinda lost here. Does anyone care to guess where I might try adjusting the overscan? Thanks.
(This post was edited by Vers on May 22, 2005, 6:34 AM)
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