Chester, Just for fun, wiggle the SSB board and see if symptoms change. Jeff -- Intrepid Video TV/VCR Repair 263 S Front St, Steelton PA 17113 717-939-7708; (F) 717-564-4952 www.intrepid-video.com www.tech-repair.net ----- Original Message ----- From: "HQ Electronics" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Thursday, January 13, 2005 7:19 PM Subject: [Techs] PCE HDTV convergence or shutdown problem- help needed
Make: PCE Model: 43Pp920217 Chassis DPTV 305 Svc manual: OEM 7621 Problem: Set came in with intermittent extremely severe misconvergence . Picture would work fine for a while then the convergence would "collapse" to what looks like a laser light show on the screen. Set then draws excessive current in excess of 2.5 amps. We have replaced both convergence C's- (good quality) no change. B+ appears to be solid, until the convergence problem starts. Then the voltages on the chassis all start pulsating. All voltages on the convergence C's pulsate. HV fails. With the symptom present the + 36 v line and - 36 volt lines to the convergence C's run drop to + 20V and - 20V. The +24V and -24V lines goes to about +15V and -15V. Vertical windings on the yoke all resistance measure the same. The + 135 v line to the Horizontal Output ckt. goes to approximately 100V. These voltages all come up to normal when any vertical yoke lead is disconnected while all the horizontal windings are left intact. The high voltage disappears when this vertical yoke feed is disabled. The AC line drain goes down to about .8A. The convergence C's seem to run too hot when the vertical yoke windings are connected. Also, something in the set smells hot. We subbed each yoke with no change or improvement. With the 135V DC line disconnected and tied to a 40W 120V light bulb the B+ is normal and regulates tightly. AC from a Sencore Powerite PR57 into each vertical yoke winding measures the same drain of .5A AC for each yoke. We do not seem to have a yoke problem What can we do to better isolate the problem? The High Voltage transformer seems to have a solid state control circuit built into it so we don't know how to run a good test on it. When we replaced the vertical output IC with the B+ disconnected to the HV Xfmr the AC drain was quite low, about .8A. After we plugged in each CRT socket and reconnected the HV Xfmr the current soared back again. We were sure to disconnect all CRT sockets when doing the yoke tests so as to avoid CRT damage. When we went backwards and disconnected the vertical yoke lead and the HV Xfmr B+ feed we still had excessive AC line drain, making it appear that something bad happened with the replacement vertical output IC. What to do next is a big dilemma at this point. Could something in the set be causing a problem with the replacement vertical output IC? The vertical output of the vertical IC is about 20V P-P with no yoke load. Chester L. Crowell -- HQ Electronics 218 N 1st ST Shelton WA 98584 360-426-3336 -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.300 / Virus Database: 265.6.11 - Release Date: 1/12/2005 _______________________________________________ Tech Repair CD...order your just $99.00 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 _______________________________________________ Tech Repair CD...order your just $99.00 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
