[TechAssist] Fixed...NAP HD2717C101 27B800, no video..(was vertical prblm)
- From: "Intrepid Video Support" <support@xxxxxxxxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Fri, 2 Apr 2004 12:13:57 -0500
Persistence pays off again...
After spending a lot of time in the vertical section, I came to the conclusion
my final fault was not in
this circuit. It was confusing since removing the vertical connector for the
yoke, I got a horizontal
line..
In my checks of IC271, I found my voltage low on pin 18(s/b 5.1v). Lifting the
pin and the voltage came
up.
On connector J251, I had 1K ohms resistance pin 5 to ground, unsoldered and
isolated problem to CRT board
as other techs had suggested. I thought I ruled the CRT board out as shows
video on the scope on each IC
and injected video and the screen lit up.
Tracing the path back I found the final two video out IC's(that I did not
replace in the beginning)
actually had pins 5 shorted to ground, lifted to confirm that pins 4,5 were
shorted.
Replaced IC's and screen lit up, though decreased vertical...I put the original
EEPROM back in set and
picture was perfect.
I appreciate everyone that sent schematics and offered their help. I couldn't
have completed this task
without the help from this list..
Thank you.
Jeff Dougherty
Intrepid Video TV/VCR
263 S Front St
Steelton PA 17113
fax...717-564-4952
www.intrepid-video.com www.tech-repair.net
----- Original Message -----
From: "Intrepid Video Support" <support@xxxxxxxxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Wednesday, March 31, 2004 1:03 PM
Subject: [TechAssist] 2nd REQ TA...NAP HD2717C101 27B800, no video..(was
vertical prblm)
Going with a fresh post on this one. I still can't find the problem.
First thing, I found the resistors and diodes for the 13 (-/+) lines bad,
replaced those and shorted
vertical IC.
Then, I had raster that was red with retrace, found the RED video IC bad on CRT
board. Also, R50
open..replaced, then back to no video.
I've tried three more vertical out IC's all OEM and NTE, still no video. With
the NTE in, I get some video
very top of screen about 1/4 inch across.
On IC271, 46/47, voltages were about a volt low and wave forms were low p-p,
replaced IC..no fix.
Wave forms in/out of SAW filter are OK.
On pin 1 over vertical yoke, which comes from pin 5 of vertical wave form shows
about 50 vpp, very high.
Pin 6,7 of vertical show low pp voltage.
I've went over and over my traces solder, replace the resistors and diode with
OEM numbers, went over the
CRT board again.
If I remove the vertical plug, I do get a horizontal line and the power LED
flashes. I checked the yoke
and it is about 1 ohm off from one on another set.
I have the schematic of this section, but am not sure what is causing these
wave forms to vary.
I put in another Philips IC and the wave forms are even farther off.
Any other ideas before I scrap this set...I've done many of these B8 for the
same problem and have never
had this type of trouble,
Thank you.
Jeff Dougherty
Intrepid Video TV/VCR
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