On Jun 16, 2:47*pm, Meat Plow wrote:
On Wed, 16 Jun 2010 11:41:41 -0700, Ippei Okamura ǝʇoɹʍ:
I took some pictures:
http://picasaweb.google.com/11747567...9742/PVM2950Q?
feat=directlink
I tried adjusting in service mode. *I was able to fill up the entire
screen with image but bowing doesn't go away. *I noticed that "H TRPZ"
has very little effect on the screen.
Any comments or suggestion will be greatly appreciated.
I guess that is the horiz trapezoid adjustment. Keep at it you'll figure
it out. Might help to have some technical literature on the set.
Thanks again!
I think all controls in service mode are working, except the
horizontal trapezoid whose effect is small. Looking at the block
diagrams in service manual, all of A (main with flyback), DX
(GEOMETRIC DISTORTION CORRECTION), and VC (V. PIN DRU, Vcc DRU, TILT
CORR) boards seem to have something related to pincushion. DX and VC
boards are sub board that are plugged on to A board.
A board: IC502 ("PIN CORR", UPC393C, 8pin bipolar analog IC), Q506
("PIN OUT", 2SK1916-53-F50), Q508 and Q509 ("PIN DRV", 2SD774-34 and
2SB733-34), T1801 ("VPOT", FERRITE TRANSFORMER), and L1802 ("", COIL
(WITH CORE)).
DX board: IC1506 ("D/A CONV", CXA1315M, pin-6 is labeled TRPZ and
traces to VC board), and IC1505 ("SAW PARA OUT", BA10358F, op amp)
VC board: IC1803 ("V-PIN-DRU", SN74LS221N, Dual Monostable
Multivibrators With Schmitt-Trigger Inputs), IC1802 ("Vcc DRU",
2SA1175-HFE), Q1804/1805/1809/1810 ("V PIN DRV 1/2/3/4", 2SA1175-HFE,
2SC2785-HFE), Q1811 ("V.PIN OUT 2", 2SC3298B-0), Q1806 ("V.PIN SW1",
2SB858-C)
From my understanding on the article I mentioned previously, N/S
pincushion is normally corrected "by using a 'transductor'.", "a
component with 2 coils and a saturable core". Looking at the diagram
on A board, there are L1802 and T1801 that are connected to VC board
with lines called V-PIN-H and V-PIN-V, respectively. At the end(?) of
VC board, lines called "SKEW+" and "SKEW-" go to Deflection York. I'm
guessing they might function as a "transductor" mentioned in the
article but I'm not sure...