[TechAssist] Re: Diode testing
- From: Paul <dntwntv@xxxxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Fri, 27 Aug 2004 11:00:28 -0700 (PDT)
That is what prompted the question. I have a fluke and a beckman and they both
read about the same in this instance. I just recieved one of the new diodes and
it checks nearly the same as the old ones for leakage on the 200ohm scale. I am
going to change them both when the other one comes in. If it fixes the problem
I will let evryone know. At this point I am still a little mystified. This has
to come under the heading of oddball.
Paul
walter wood <wwood_38478@xxxxxxxxx> wrote:
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 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
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