[TechAssist] Re: Sony KV32XBR26 About Zener D1407 (8-719-110-90)
- From: Philip Bader <tjanphyl@xxxxxxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Fri, 17 Oct 2003 10:32:08 -0400
Thanks for the clarification. It seems the schemos differentiate between
the two terms depending on their function and use in the circuit.
In regulation circuitry where a transistor base is strapped with one of
these diodes, they refer to them as a zener.
When placed across the output source (to ground), and are intended to
short and "give their lives" the technical pub seems to use "avalanche"
as the term of preference, though the terms are admittedly synonymous.
One is for a continuous use, the later seems a "one shot" use.
Just rambling.At days end I still go home to the dog...
Synomonous with "feed me!"
;-)
Phil Bader
becyn wrote:
>
> A clarification;
> "avalanche diode and zener are synonymous-no difference!
> The zener in a crowbar circuit does nothing until an overvoltage condition
> occurs. When the voltage reaches the "knee" breakdown, the diode receives
> max supply current and melts-BY DESIGN. This in turn forces the SMPS into
> overcurrent shutdown. Better to melt a 50 cent diode than a $20 micro...or
> more.
> Yes, the brave little diode gives it's life for the greater good.
> A normal zener circuit always has a series limiting resistor to control the
> maximum current and keep the diode within non-melting range.
>
> Ok I feel better now...
>
> Jim McVey
> McVey Alltronix
> 327 Broadway
> Newburgh Ny 12550
> ph: 845 561 8383
> fx: 845 561 9017
> Consumer electronics &
> computer service.
> Factory authorized for
> over twenty brands.
> ----- Original Message -----
> From: "Philip Bader" <tjanphyl@xxxxxxxxxxxxxxx>
> To: <techassist@xxxxxxxxxxxxx>
> Sent: Wednesday, October 15, 2003 11:02 AM
> Subject: [TechAssist] Re: Sony KV32XBR26 About Zener D1407 (8-719-110-90)
>
> > Most applications utilising cthe rowbar ckts above I've seen use an
> > "avalanche diode" instead of a standard zener.Once the breakdown
> > voltage is attained it shorts permanently.
> > Phil Bader
> >
> > J Silverman wrote:
> > >
> > > If the zener is used for overvoltage protection the idea is for it to
> short
> > > quickly which causes the SMPS to shut down due to the SMPS protection
> > > circuit. Normally, the overvoltage zener is not conducting or
> dissipating
> > > power. Use of higher wattage zeners could delay the shorting action
> which
> > > could might result in damage to components subjected to the overvoltage.
> The
> > > zener is considered a cheap, expendible "crowbar". In better made
> equipment,
> > > the overvoltage zener is just used to trigger an SCR. The SCR handles
> the
> > > short current until the power supply shuts down. In that kind of
> equipment,
> > > the zener and the SCR survive. I never gave it much thought, but
> something
> > > like that could easily be made, just requiring two leads, to tack into
> power
> > > supplies for troubleshooting, where overvoltage could cause damage to
> > > sensitive components.
> > > Jerry Silverman
> > > Greentron Inc
> > > 4 Newland Ave
> > > Greenville SC 29609
> > > 864 232 3889
> > > Fax 271 2080
> > > mailto:greentron@xxxxxxx
> > > ----- Original Message -----
> > > From: "Philip Bader" <tjanphyl@xxxxxxxxxxxxxxx>
> > > To: <techassist@xxxxxxxxxxxxx>
> > > Sent: Tuesday, October 14, 2003 2:15 PM
> > > Subject: [TechAssist] Re: Sony KV32XBR26 About Zener D1407
> (8-719-110-90)
> > >
> > > > Yes,tho not considered "proper". cathode-anode,cathode-anode.
> > > > Remember to use oversized wattages, to compensate for voltage drops
> > > > across the different voltage zeners.
> > > > Such as, you need a 120 volt zener, and you series a 100 volt and a 20
> > > > volt zener.Different current disappations for each.
> > > > If you make the 120 volts zener with two 60 volt zeners, even voltage
> > > > drop across them would occur.
> > > > If half-watt is called for, I would use one watters.
> > > >
> > > > J Silverman wrote:
> > > > >
> > > > > You can string zener diodes in series to make up a specific voltage
> when
> > > you
> > > > > need one quickly. One problem is if the zener is used as an
> overvoltage
> > > > > protector it will just blow up again if the overvoltage problem was
> not
> > > > > corrected.
> > > > > Jerry Silverman
> > > > > Greentron Inc
> > > > > 4 Newland Ave
> > > > > Greenville SC 29609
> > > > > 864 232 3889
> > > > > Fax 271 2080
> > > > > mailto:greentron@xxxxxxx
> > > > > ----- Original Message -----
> > > > > From: "Neil Bowman" <tvdoctors@xxxxxxxxxxxxx>
> > > > > To: <techassist@xxxxxxxxxxxxx>
> > > > > Sent: Tuesday, October 14, 2003 12:08 AM
> > > > > Subject: [TechAssist] Sony KV32XBR26 About Zener D1407
> (8-719-110-90)
> > > > >
> > > > > > I've checked Tritronics and they don't have in stock. My local
> > > supplier
> > > > > here in Washington State didn't have it either but she crossed
> > > 8-719-110-90
> > > > > to NTE5037A and shipped it today. I checked the value after I hung
> up
> > > and
> > > > > it's a listed as a 36 volt zener diode. Would this be satifactory.
> > > This is
> > > > > the craziest little diode that I have tried to find in stock.
> Anyone
> > > have
> > > > > one to put in a envelope to send me, in case the NTE doesn't work
> out?
> > > > > Customer want's set fixed as quick as possible. Neil
> > > > > >
> > > > > > TV Doctors
> > > > > > Monroe,Wa
> > > > > >
> > > > >
> > >
> ****************************************************************************
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> > > > --
> > > > Philip Bader
> > > > Jan Phyl TV Inc. (estab. 1976)
> > > > 3420 Recker Hwy. Winter Haven, Fl. 33880
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> > --
> > Philip Bader
> > Jan Phyl TV Inc. (estab. 1976)
> > 3420 Recker Hwy. Winter Haven, Fl. 33880
> > Fax (863) 299-8821
> > email: tjanphyl@xxxxxxxxxxxxxxx
> > For Professional Technicians Only
> >
> >
> ****************************************************************************
> *
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--
Philip Bader
Jan Phyl TV Inc. (estab. 1976)
3420 Recker Hwy. Winter Haven, Fl. 33880
Fax (863) 299-8821
email: tjanphyl@xxxxxxxxxxxxxxx
For Professional Technicians Only
*****************************************************************************
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