[TechAssist] Re: ***** Zener or Avalance diode? *****

Bob, 

Thanks for the link.  I connected, printed it out, and studied it.  My
degrees are not in engineering, but I took quite a few courses, so will
attempt a synopsis of that report for those who couldn't read it
themselves.

Both (zener & avalanche) diodes are designed to operate in reverse bias. 
Both are very high impedance below their rated voltage.  Both begin to
conduct at their designated breakdown voltage.  The difference is in
their usage.  The zener is intended for voltage <regulation>, to supply a
regulated voltage for small current or to control a power transister for
larger current applications.  It will always use a current limiting
resistor.  The avalanche is used for overvoltage protection.  Once it's
breakdown voltage is exceeded, it becomes a permanent short circuit.

So, in the case of the Sony, D648 must be properly called an avalanche
diode and NTE 570 should be fine in that application.

Thanks, Bob, for your help in this.  Some may find this boring, but I
learned something from it.


Ken Smith
Gulf Technical Services
3034 Gulf Breeze Parkway
Gulf Breeze, FL  32563
850-934-8324 (Voice) 850-932-0819 (Fax)


On Sat, 31 Aug 2002 15:50:24 -0400 "Gemini Computer & TV"
<geminitv@xxxxxxxxxxxxxxxx> writes:
> 
> Actually, make that
>
http://www.deas.harvard.edu/courses/es154/lectures/lecture_2/breakdown/br
eak
> down.html
> 
> Bob Waterman, CET #RI-28
> Master Technician License #9109
> Service Manager
> Gemini Computer, TV, & Security Alarms
> (508)695-7302
> (508)695-7769 FAX
> geminitv@xxxxxxxxxxxxxxxx
> geminitv@xxxxxxx
> 
> ----- Original Message -----
> From: "Hugh at Main TV" <maintv2002@xxxxxxxxxxxxx>
> To: <techassist@xxxxxxxxxxxxx>
> Sent: Saturday, August 31, 2002 1:28 PM
> Subject: [TechAssist] Re: ***** Zener or Avalance diode? *****
> 
> 
> > The link you posted is not good--maybe try again?
> > Thanks for input.
> > Hugh
> > Main TV
> >
> > Ty Kraemer wrote:
> >
> > >Gentlemen,
> > >Surprise!
> > >In short form:
> > >Below  6 volts the Zener affect is in force.
> > >At 6 volts both are in affect.
> > >Above this voltage, only the Avalanche affect comes to play.
> > >If you want to understand the Zener/Avalanche principal, fallow 
> this
> lead:
> >
>
>http://www.deas.harvard.edu/courses/es154/lectures/lecture_2/breakdown/b
rea
> k
> > >down.html
> > >The address is all one line.
> > >
> > >Ty
> > >
> > >Tiberius (Ty) Kraemer
> > >Blue Star Electronics
> > >3312 Silverton Rd.NE
> > >Salem, OR 97303-2753
> > >Phone: 503 391 1491
> > >E-Mail: ty1k(at)attbi.com
> > >
> > >
> > >----- Original Message -----
> > >From: <gulftech@xxxxxxxx>
> > >To: <techassist@xxxxxxxxxxxxx>
> > >Sent: Thursday, August 29, 2002 7:28 AM
> > >Subject: [TechAssist] Re: Sony KV32S25--Zener or Avalance diode?
> > >
> > >
> > >
> > >Bob,
> > >
> > >Thanks for that information.  I will file that away for my next 
> Fulton
> > >order.
> > >
> > >Still, it doesn't answer the basic questions--"What is the 
> difference
> > >between a zener and an avalanche diode?" and "Will an NTE570 sub 
> for
> > >D648?"
> > >
> > >My understanding is that an avalanche and a zener are the same 
> animal.
> > >The NTE web site provided little help for either question.
> > >
> > >Since D648 is used as a crowbar (protection) only,  the diode is
> > >essentially out of the circuit UNLESS the regulator ckt fails.  
> For that
> > >reason, I always replace IC643 (DM-58, 8-749-012-13) whenever I 
> find D648
> > >shorted.
> > >
> > >I used an NTE570 to replace D648 a while back when I found I was 
> out of
> > >the original and no time for an order.  Time will tell.
> > >
> > >
> > >Ken Smith
> > >Gulf Technical Services
> > >3034 Gulf Breeze Parkway
> > >Gulf Breeze, FL  32563
> > >850-934-8324 (Voice) 850-932-0819 (Fax)
> > >
> > >
> > >On Thu, 29 Aug 2002 07:34:38 -0400 "Gemini Computer & TV"
> > ><geminitv@xxxxxxxxxxxxxxxx> writes:
> > >
> > >
> > >>I am working on the exact same model right now. D648 is a 150 
> volt
> > >>zener,
> > >>(generic# EZ0150AV1), Sony part # 8-719-057-52.
> > >>
> > >>Bob Waterman, CET #RI-28
> > >>Master Technician License #9109
> > >>Service Manager
> > >>Gemini Computer, TV, & Security Alarms
> > >>(508)695-7302
> > >>(508)695-7769 FAX
> > >>geminitv@xxxxxxxxxxxxxxxx
> > >>geminitv@xxxxxxx
> > >>
> > >>----- Original Message -----
> > >>From: "Hugh at Main TV" <maintv2002@xxxxxxxxxxxxx>
> > >>To: <techassist@xxxxxxxxxxxxx>
> > >>Sent: Wednesday, August 28, 2002 7:37 PM
> > >>Subject: [TechAssist] Sony KV32S25--Zener or Avalance diode?
> > >>
> > >>
> > >>
> > >>
> > >>>Power surge hit set--replaced 2SC4834s, all small diodes in
> > >>>
> > >>>
> > >>Swmode, C609
> > >>
> > >>
> > >>>& C610 caps,
> > >>>R607 0.1 ohm,  all 22 ohm res. in power, then found D648 
> shorted.
> > >>>
> > >>>
> > >>No
> > >>
> > >>
> > >>>sub as per Sams or NTE,
> > >>>symbol on Sams looks like zener--- part # is EZ0150AV1---- I put
> > >>>
> > >>>
> > >>in an
> > >>
> > >>
> > >>>NTE570 Avalance diode--set seems to work ok... Question I have 
> is
> > >>>
> > >>>
> > >>what
> > >>
> > >>
> > >>>is difference between a 150 zener and 150 v avalance diode?
> > >>>
> > >>>
> > >>Would they
> > >>
> > >>
> > >>>both work as protection on 135v power line?
> > >>>Hugh
> > >>>
> > >>>--
> > >>>Hugh Thornley
> > >>>Main TV
> > >>>636 Main St.
> > >>>Longmont, Colorado 80501
> > >>>303-776-6955
> > >>>maintv2002@xxxxxxxxxxxxx
> > >>>
> > >>>
> > >>>
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> >
> > --
> > Hugh Thornley
> > Main TV
> > 636 Main St.
> > Longmont, Colorado 80501
> > 303-776-6955
> > maintv2002@xxxxxxxxxxxxx
> >
> >
> >
> >
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