Q480 is your HV regulator that feeds B+ in to the FBT at pin # 2 . This voltage is monitored via Q485 for x-ray protection. Q480 should have 120V on collector and regulate to 115V on the emitter. Q481 is the error amp that drives Q480. D481 is a 4.7V zener on the base of Q481 which gets it's reference from IC482. Voltages on this IC are as follows from pin 1 to 9: 11.8 4.4 4.3 4.6 0.0 3.6 9.0 9.0 11.8 . Pin # 2 is the ref voltage that drives Q481 HTH Keith Trumbla BEM Electronics Inc. Suite 212-530 Century St. WPG. MB. R3H 0Y4 Canada Ph.(204)775-2875 Fax.(204)774-9192 SITE UPDATED ! www.bemelectronics.com ----- Original Message ----- From: "Larry Eastman" <videotech@xxxxxxxxxxxx> To: "techassist" <techassist@xxxxxxxxxxxxx> Sent: Thursday, October 30, 2003 1:37 PM Subject: [TechAssist] Toshiba CF3564B immediate shutdown Q480 shorted e-c > Hi Guys, this 35" Toshiba starts up and HV immediately shuts down, I > don`t have the schematic > and can`t figure out what Q480 is for, but it`s shorted e-c. If I remove > the plug marked PD03 > from the HV board the set will stay on, (idiot lights on front stay on, > ) HOT is not shorted, > and none of the fuses are blown,I have no tech notes on this model, > Tritronics web page shows the original Q480, 2SD1294(FA) is NLA but > show a RCA 2SD1294 (no FA) is available, can anyone tell me what Q480`s > purpose is and if you`ve seen this one before whether replacing Q480 > will fix it or not? TIA, Larry E > Larry Eastman > American TV & Electronics > Crystal River, Fl. 34428 > > **************************************************************************** * > Classifieds! Buy or Sell! > http://sell.tech-assist.org > The Tech Address Book: > http://www.tech-assist.org/secure/tip/contact.htm > Add a Repair Tip Here, or Change/Remove your Email Address: > http://www.tech-assist.org/secure/tip/main.htm > Lost Password: > http://www.tech-assist.org and select "Lost your Login Info?". > Email Archives: > //www.freelists.org/archives/techassist/ > ***************************************************************************** Classifieds! Buy or Sell! http://sell.tech-assist.org The Tech Address Book: http://www.tech-assist.org/secure/tip/contact.htm Add a Repair Tip Here, or Change/Remove your Email Address: http://www.tech-assist.org/secure/tip/main.htm Lost Password: http://www.tech-assist.org and select "Lost your Login Info?". Email Archives: //www.freelists.org/archives/techassist/