Hi, i’m an Italian technician.
I’ve an hard to solve problem with a monitor (and english too!) and I’ve past a lot of time to find repair it.
This is the problem: Monitor Mirò Visualsensations, FCC EVOKD1730T (KDS Korea datasystem) PWB-122A REV-03. The HOT BU2520DF dead with the resistor FR801 in the B+ line, caused by the fbt with the open cap in the secondary.
Replaced the fbt and the HOT.
The monitor works BUT also without the signal from PC (OSD working) I can see an thin orizontal line avcross all the display. From left to right the line is white, no line at the center, and black. I’ve tested all the cap around the orizontal circuit, the mosfet and other transistor, the B+ coil all the ceramic capacitor, I’ve changed the diode FMPG2F , TDA4858, TDA4866, ecc. The signal at tbe base of the hot seem to be ok . At the 800x600 the monitor works acceptable but at other resolutions NO because the line across the display is bigger and is deplaced in other display's position.
Nobody in the italian group can help me.
If you can help with the diagnoses (?)and the suggestions to fix ( is very hard caused my bad english also) i’ll be very happy.
Best regards
Alberto

You have vertical fault not horizontal.

Check scan coil connector and IC301.

Rich

Many thanks. So i'have changed the vertical (twice ) ic TDA4866 and checked the cap around it for high esr. I have resoldered the connectors'pin of the yoke too. If you need i can send some photo of the display with the troubling thin orizontal lines.
Alberto

Yes please just post the pictures here.

Rich B

Here are same photos. Not good quality but explicative (i hope, sic!)
Many thanks
Albertohttp://www.network54.com/Realm/tmp/1131610568.JPG

Hi sorry

I was mistaken about your description of the fault you do not have frame collapse but oscilation on the frame scan.

Check
C302
C303
C304
C305
C308 by substitution
R307

and the + & - 15V rails.

Rich

Ok, thanks, i'll try.
Alberto

Hi Rich, i’d done the test.
I’d found:
c302 (polyester 222 100v good)
c303 (polyester 222 100v good)
c304 (221 connected at the pin 4 of the IC301 TDA4866, good)
c308 (polyester 682 100v replaced)
c305 NOT FOUND ?
R4,7 ohm with the value (my be) of 5,1 ohm, replaced with another one.

The fault still persist. Can I doubt about the FBT?
I send some images of the pcb.
I wait for your suggestion.
Many thanks
Alberto

Sorry they are different schematics.

The components are on

Pin 2 of frame IC 2 cap's
Pin 4 -V of frame IC 1 off
Pin 5 output of frame IC usually 220n 1 off
between pin 3 & 6 of frame IC 1 off.

Rich