[TechAssist] Re: Diode testing
- From: walter wood <wwood_38478@xxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Fri, 27 Aug 2004 08:03:38 -0700 (PDT)
I've seen that happen in circuit, but never out of
circuit.
Maybe someone smarter than me can explain it.
Walter
--- Wayne Vanaman <Wayne@xxxxxxxxxxxxxxxxxxxxx>
wrote:
> Wendsday I pull CR4401 pn 242907 from an RCA 169
> chassis, and it
> measured -1.2 volts on the diode check setting
> with a fluke 77 series 3.
> Minus volts out of circuit on a
> diode? What the heck? Changed the battery in
> the meter, same thing.
> Changed the diode and the set worked.
>
> How the heck do you get minus volts? That means
> that
> there was some sort of capacitance/pn junction
> problem with that diode.
>
> Minus ohms.
>
> Wayne Vanaman
> Omega Electronics
> 6904 W Fairfield Dr
> Pensacola, Fl. 32506-3310
>
> Wayne@xxxxxxxxxxxxxxxxxxxxx
> WWW.PensacolaTVRepair.Com
>
> 850-456-5995 voice
> 850-458-6369 fax
>
>
> ----- Original Message -----
> From: "walter wood" <wwood_38478@xxxxxxxxx>
> To: <techassist@xxxxxxxxxxxxx>
> Sent: Thursday, August 26, 2004 9:24 PM
> Subject: [TechAssist] Re: Diode testing
>
>
> > It seems to depend on the meter, as to what the
> > diode check position will read.
> > I have a Micronta(inexpensive radio shack) that
> > reads 820 t0 840 consistantly on good diodes.
> > I have two Fluke meters, ond old (series 73)
> but
> > great, and an expensive Model 83 series three.
> > They both consistantly read 460 on the diode
> scale.
> > I think you diodes are leaky.
> > You have enough evidence that I would certainly
> > replace them.
> > Check the new ones out of circuit before
> installing
> > them, and if weird make a note of it.
> > There are some odd ball things out there.
> > i've got a large spiral notebook full of such
> > measurments.
> > ALWAYS, use the same meter though, for
> comparaison,
> > or note the results with the different ones.
> > Another thing I like to do is take resistance
> > measurements on key components, such as
> convergence
> > ic's, regulators, outputs etc. on common
> products,
> > on a set that is working correctly.
> > I note this, and it helps more often than not.
> > SAMS used to provide this.
> > HTH
> > Walter
> > --- Paul <dntwntv@xxxxxxxxxxxxx> wrote:
> >
> > > When checking diodes for leakage, what range
> on
> > > the ohm meter do you use and is there an
> > > acceptable amount? Sounds like electronics
> 101
> > > but I have a couple of diodes that are flat
> case
> > > diodes mounted on a heat sink. They read 160
> > > front to back on the diode check. No reading
> back
> > > to front. However they read 20k on the ohms
> > > scale. If heated this reading goes down to 2
> or 3
> > > K. I normally set my meter on 100k ohm for
> > > leakage. I thought they must be leaking. But
> > > wondered if there are some big diodes that
> test
> > > this way normally? Someone said that 10X the
> back
> > > to front was normal. These are in the
> secondary
> > > of a SMPS + & -- 25v to convergence amps.
> > >
> > > Paul
> > >
> > > Paul ,B
> > > Central TV&Video
> > > 911W Grand Ave
> > > Grover Beach Ca.
> > > (805)481-8084
> > >
> > >
> > >
> >
>
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> >
> > =====
> > Walter Wood
> > Future Tech Home Center
> > 2786 Hwy. 43 N.
> > Lawrenceburg Tn. 38464
> > 931-829-3337
> > Fax 931-829-4044
> > mailto:wwood_38478@xxxxxxxxx
> >
> >
>
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=====
Walter Wood
Future Tech Home Center
2786 Hwy. 43 N.
Lawrenceburg Tn. 38464
931-829-3337
Fax 931-829-4044
mailto:wwood_38478@xxxxxxxxx
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