View previous topic :: View next topic |
Author |
Message |
Steve E Guest
|
Posted: Sun Mar 01, 2009 9:27 pm Post subject: Vertical overscan ?? |
|
|
My parents have a 27PT9015D/37 Philips flat screen crt tv that has what looks like vertical overscan , there are retrace lines about 2 inches down from the top . Please if any one has seen this before or has a schematic any help would be greatly appreciated . Thank you for your time . |
|
Back to top |
|
|
jts1957
Joined: 24 Nov 2008 Posts: 2476 Location: Far, Far Away
|
Posted: Mon Mar 02, 2009 12:06 am Post subject: |
|
|
That sounds like "foldover."
Check electrolytics in Vertical output circuit and its power supply(ies). |
|
Back to top |
|
|
torbjorn
Joined: 07 Jun 2007 Posts: 370 Location: Sweden
|
Posted: Mon Mar 02, 2009 7:59 am Post subject: |
|
|
Another common cause for vertical overscan (which in turn can cause clipping in the output stage and then retrace lines) is that the feedback shunt at the "cold" end of the vertical coils is off correct value. Usually, this is a resistor of for example 1 ohm or 2,2 ohm, in some cases it is built up of two parallel resistors and if one of those gets open circuit, you will have this symptom.
If the problem has evolved gradually over a long period of time, then it is probably due to electrolytics, but if the tv worked well and then suddenly got the fault, then it is more probable that it is a resistor that has went open circuit, a bad solder joint or something like that. |
|
Back to top |
|
|
minnie
Joined: 18 Aug 2005 Posts: 2880 Location: Hell
|
Posted: Mon Mar 02, 2009 6:46 pm Post subject: |
|
|
Replace the pump up cap. Usually 100uf@25 vdc near the vertical IC. |
|
Back to top |
|
|
|
|
|
You can post new topics in this forum You can reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum
|
eServiceInfo on FB -
Service Manuals Free Download -
Service Diagrams
Free TV Schematics Download -
HARDW.net -
Pinout Master -
Jabse Service Manual Search -
Jabse.InK -
onTap.bg
SnimkiOt.com -
Poblizo.com : пътешествия
Latest Service Manuals :
4A141 AirChief • t1 LG • hfe denon avr-1912 2112ci schematics DEN • WD-6021 C LG • 2n6674 2n6675 Inchange Semiconductor • Universum_Modell-Chassis Universum • mps6514 Fairchild Semiconductor • ceu02n6a ced02n6a CET • Alan-4522 MIDLAND • SLV-X717 X817 X827 X837ME Sony •
|