3 Nov
1999
3 Nov
'99
11:54 a.m.
Its not a bad idea to test a diode at the current for which it was designed.
If you want to do that, it won't be a waste of your effort. However, I
would guess it's time not well spent to continue fiddling with the diode
you've apparently shown has too much reverse leakage to be of use.
I'm persuaded (perhaps incorrectly) that your diode is from a rectifier or
switching circuit associated with the battery charging/power conversion
process. If it is, then it's probably a rectifier and not a signal diode.
You can probably replace it for less than a dollar and get several spares in
the same operation.
Dick
-----Original Message-----
From: jpero(a)cgocable.net <jpero(a)cgocable.net>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Wednesday, November 03, 1999 5:48 PM
Subject: Re: schottky diode again..
Date: Thu, 4 Nov 1999 00:10:57 +0000 (GMT)
Reply-to: classiccmp(a)u.washington.edu
From: ard(a)p850ug1.demon.co.uk (Tony Duell)
To: "Discussion re-collecting of classic computers"
<classiccmp(a)u.washington.edu>
Subject: Re: schottky diode again..
Have you tried reading the 'manuals' for most
modern meters (or other
test gear)? They're useless for actually telling you what the instrument
is doing. At one time, such manuals contained schematics, simplified
schematics, circuit descriptions, etc. Not any more :-(
Tony as usual is right. I don't read those modern manuals these
days. Except skimming for few areas just to be sure.
Surely the sort of person who buys a multimeter is also the sort of
person who can read/understand a schematic. So the lack of such
information is something of a puzzle to me.
That DMM is built by me in kit form and calibrated it for voltage and
current. Good as any normal DMM should do. Same with ESR. no
calibrating required. Zeroes when shorting and press the button
twice. One push turns on ESR, when on and probes is showing low
resistance or shorted together and pressed button again zeroes it to
account for losses in internal circuits and probe wires. That ESR
meter has real docs because it's kit and info that explains why can
most of time can measure caps in circuit. Came from Dick Electronics
(Aus) for about 40 US. The pot is only there to preset for voltage
cut off to warn of low battery condition.
For this reason, I _always_ test every feature of a new piece of test
gear, often in unconventional ways. I _will_ check diodes on resistance
ranges to see what happens. Often the lower resistance ranges _do_
provide enough current to provide a useful test on diodes, and the
ability to do the check at more than one current sometimes picks up
'rogue' diodes.
Correct as I suspected by playing.
My DMM actually shows better when I move from low res scales to mid
to high ranges. I need to grab another meter to see what it do on my
dmm. :-) Tony inpsired me to this!
-tony
Wizard