Zeners in series...
in [Repair]
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From: Nox on 12 Mar 2010 05:30 Hey there, could somebody take a quick look at this circuit and try to explain me what's the purpose of the 2 zeners near the interrogative point ? Here's the schematic: http://img706.imageshack.us/img706/5493/psud.png If they are working as voltage stabilizer, shouldn't there be a resistor between them and the rectifier?? To be honest those 2 zeners is what I've found on the circuit but.... the parts list say that D615 and D614 should be a 120V zener and a 31V 100pF varactor diode (1S3150A)... this makes no sense to me :S
From: Sansui Samari on 12 Mar 2010 06:21 On Mar 12, 2:30 am, "Nox" <a...(a)def.ghi...ecc...ecc...ecc...> wrote: > Hey there, could somebody take a quick look at this circuit and try to > explain me what's the purpose of the 2 zeners near the interrogative point ? > Here's the schematic:http://img706.imageshack.us/img706/5493/psud.png > If they are working as voltage stabilizer, shouldn't there be a resistor > between them and the rectifier?? > To be honest those 2 zeners is what I've found on the circuit but.... the > parts list say that D615 and D614 should be a 120V zener and a 31V 100pF > varactor diode (1S3150A)... this makes no sense to me :S Maybe they found two zeners that would split the voltage fine, which would be cheaper, and forgot to update the parts list.
From: Samuel M. Goldwasser on 12 Mar 2010 08:30 Sansui Samari <jimjam1942(a)gmail.com> writes: > On Mar 12, 2:30�am, "Nox" <a...(a)def.ghi...ecc...ecc...ecc...> wrote: > > Hey there, could somebody take a quick look at this circuit and try to > > explain me what's the purpose of the 2 zeners near the interrogative point ? > > Here's the schematic:http://img706.imageshack.us/img706/5493/psud.png > > If they are working as voltage stabilizer, shouldn't there be a resistor > > between them and the rectifier?? > > To be honest those 2 zeners is what I've found on the circuit but.... the > > parts list say that D615 and D614 should be a 120V zener and a 31V 100pF > > varactor diode (1S3150A)... this makes no sense to me :S > > Maybe they found two zeners that would split the voltage fine, which > would be cheaper, and forgot to update the parts list. A varactor diode there makes even less sense. They probably needed a 270 V zener as protection against excessive voltage at that location and there was no single zener that was 270 and adequate power. C603 and the other component upstream of it limit the current. -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs.
From: WangoTango on 12 Mar 2010 10:48 In article <rJomn.134582$813.30472(a)tornado.fastwebnet.it>, abc(a)def.ghi...ecc...ecc...ecc... says... > Hey there, could somebody take a quick look at this circuit and try to > explain me what's the purpose of the 2 zeners near the interrogative point ? > Here's the schematic: http://img706.imageshack.us/img706/5493/psud.png > If they are working as voltage stabilizer, shouldn't there be a resistor > between them and the rectifier?? > To be honest those 2 zeners is what I've found on the circuit but.... the > parts list say that D615 and D614 should be a 120V zener and a 31V 100pF > varactor diode (1S3150A)... this makes no sense to me :S Looks like a 270V clamp to me.
From: Dave Platt on 12 Mar 2010 14:03
In article <rJomn.134582$813.30472(a)tornado.fastwebnet.it>, Nox <abc(a)def.ghi...ecc...ecc...ecc...> wrote: >Hey there, could somebody take a quick look at this circuit and try to >explain me what's the purpose of the 2 zeners near the interrogative point ? >Here's the schematic: http://img706.imageshack.us/img706/5493/psud.png >If they are working as voltage stabilizer, shouldn't there be a resistor >between them and the rectifier?? It appears to me as if they are, as you say, working as a voltage stabilizer / regulator. There is a resistor present, to limit the current flowing through them and through the rectifier. If you trace out the inputs to the rectifier bridge, you'll see that one side goes back through connection 15 and then to the "0V" side of the lowest secondary winding. The connection to the other input goes to the heavy horizontal bus (which appears to serve as a ground reference), and this bus is connected to the "850V" end of the high-voltage secondary winding through R47 (which is a 3.3M resistor). So, the winding develops a high AC voltage, which is fed to the bridge in a current-limited fashion (via R47), rectified to create high-voltage DC, and the DC voltage is clipped/limited by the series-connected zeners. >To be honest those 2 zeners is what I've found on the circuit but.... the >parts list say that D615 and D614 should be a 120V zener and a 31V 100pF >varactor diode (1S3150A)... this makes no sense to me :S A 31-volt varactor? DOesn't make much sense to me either. -- Dave Platt <dplatt(a)radagast.org> AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |