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" <[EMAIL PROTECTED]> To: "ELECTRONICS PROFESSIONALS LIST" <[EMAIL PROTECTED]> Sent: Wednesday, March 31, 2004 1:04 PM Subject: [Techs] 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 _______________________________________________ Tech Repair CD...order your just $49.00 plus shipping...One year of updates free. www.intrepid-video.com www.tech-repair.net Techs mailing list [EMAIL PROTECTED] http://intrepid-video.com/mailman/listinfo/techs_intrepid-video.com
