Kortek K1-2-V0 monitor no pic

[kardenm]

Need some help.

I have a Kortek K1-2-V0 which collapsed to a horiz white line then to no picture at all (blank screen).

High voltage IS present (aprox 20,000 KV).  I replaced Q402 (the HOT) but no change.

Yoke resistance is 2 ohms and 50 ohms per spec.

Can someone tell me the most likely cause of this problem or what I should check next?

Thanks!

[ed12]

hi
chk your b+'s
make sure u have 12-20vdc to your
vert ouput ic
start there

ed

[kardenm]

Thanks ed12.  I'll check it out.

[kardenm]

RE: ed12. 

B+ comming out of the power supply is 118vdc. 

Not sure where to check voltage to the "vert output ic". ??

[lilshawn]

vertical output IC should be somewhere attached to a heatsink. most are flat and have about 10 pins on them.

http://www.electronicrepairguide.com/monitor-horizontal-lines.html

[kardenm]

Thanks lilshawn.  Good information!

This board has a combined vert/horiz ic (ic 401, HA11235) soldered directly to the board (no socket).  I do have a spare and can swap it out.  Do you think I need to try that?

Voltages on the vert side are:  pin1=3.2, pin2=1.1, pin3=3.2, pin4=3.8, pin5=7.2, pin6=11.7, pin7=5.2, pin8=5.3.

[lilshawn]

That is a sync processor. it separates the sync and supplies horizontal and vertical pulses to the appropriate systems.

http://pdf1.alldatasheet.com/datasheet-pdf/view/63433/HITACHI/HA11235.html

it could be used to directly drive the vertical... I'd check backwards from the yoke for any burned components or bum capacitors. check resistors for burns or evidence of being hot. if all looks good, go ahead and replace the 11235 and see if it's go.

if it doesn't immediately fire up after changing the 11235 then kill it and start looking some more... you have a chance of killing the 11235 .

[ed12]

hi
not to step on toe's here
but ha11235 is a pre drive ic
there should be 2 vert out transistor's as per this pdf
and a small driver transistor
the nick need's to chk cap's and pay attenion to a .1mf at 16v tataliumin it must be that spec
also yes work backward's from the yoke
reason we say this is so u do not burn a line in your tube
do your chk's fast

ed

[kardenm]

Thank you both lilshawn and ed12 !  Really appreciate the suggestions and the links.

I'll do some more checking.

ed12. What is a "nick" 

[ed12]

hi
kardenm is your nick=name

ed

[lilshawn]

Thank you both lilshawn and ed12 !  Really appreciate the suggestions and the links.

I'll do some more checking.

ed12. What is a "nick" 

does "OP" make more sense to you? 

[kardenm]

Ha Ha.  I know what OP means!!