[TechAssist] HELP SONY KP53HS30 no horiz B+
- From: "tony saracco" <tcselectronics@xxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Tue, 8 Jun 2004 08:36:02 -0500
My first visit to this set is as follows:
This set will come on for about 15 seconds with no raster or sound ( nothing is
observed looking into the lenses not even the blanking pulses.) then set shuts
down with 4 blinks. this according to the manual is no vert deflection or +15v
source. the vert deflection is there and the power supplies are OK. only
strange thing is the VP signal should be 0v and is 16v. when I disconnect the
VP line a code 7 is displayed after shutdown and still no raster at all. Code 7
is loss of horiz deflection. The operation of this horiz circuit is tricky and
is driving me in circles, I checked all components statically for shorts and
came up with none. I did notice that Q8027 appears to regulate the B+ to the
horiz sweep output but its voltage does not come above 4 volts and is leading
me towards thinking its bad.any tips on troubleshooting the sweep /HV circuits
or the RA-6 training manual would help greatly.
My second try armed with more knowledge and a few parts.
After downloading the training manual and replacing Q 8027 (B+ reg cont trans)
and Q8024 H out I am still not getting B+ to the output. Q 8027 has 135v on the
gate and the source and only a few volts at the drain. I have changed the
zenior off the gate and statically checked all components around it. I am now
looking towards the PWM modulation IC as the problem, IC 8005. the pin EW
signal is at pin 6 ( maybe low only .8vpp) and only a momentary pulse of signal
at pin 3 to Q8027. has anyone had a problem with no B+ to the H out on this set
and has anyone replaced IC8005.
one note, I have bypassed Q8027 to see if deflection returns and set comes up
with excess width ( due to high B+) so I don't think there is any secondary
problems with the horiz out circuit as ran circuit for several minuets and ran
OK.
any suggestions before I order IC8005
Tony Saracco
TCS ELECTRONICS
406 Andra Ct.
Gilberts, IL 60136
tcselectronics@xxxxxxxxx
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