[TechAssist] Sony TV, KV2680R , no Horizontal sync
- From: Gary McCartney <gary@xxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Thu, 01 Apr 2004 19:37:37 -0500
This set came in after customer had it in a differnt shop. The regulator
IC was missing and the AFT module was unsoldered from the board. I
installed new regulator and soldered up the connections in the AFT
module before resoldering it to the board. Also soldered much of the
main board for poor connections. Picture came up really well for an
older set, but after running 5 minutes or so it lost horizontal sync.
Vertical sync was ok. Unplugged set to cool off thinking it was a
thermal problem. When plugged back in, still no hor. sync. Then I
connected external video to the A/V input jacks and the same problem was
there when switched from antenna to video input. The on-screen green and
red graphics are in sync even though the video information is out of
sync. Tapping the parts on the board has no effect.
9V B+ supply measures 9.34V. Scoped waveforms on jungle IC, IC 301
CX20129. Sync waveforms at pins 3 and 13 measure ok. I posted partial
schematic on a temporary basis for you to view:
http://www.number63.ca/kv2680.jpg
Varying RV501 will vary the hor. frequency and turning it all the way to
end end makes TV go into shutdown. I changed a number of small electro
caps in the jungle area and also C520 according to tech tip but still no
sync.
The customer is willing to spend a fair buck for the repair because he
loves the console cabinet.
Thanks for any help.
--
Gary McCartney
McCartney Electronics
Guelph Ontario Canada
Est. 1984
email: gary (at) number63.ca
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