18 Jul
2000
18 Jul
'00
3:39 a.m.
Am I right in assuming DVM=digital voltmeter?
a
-----Original Message-----
From: Douglas Quebbeman [mailto:dhquebbeman@theestopinalgroup.com]
Sent: 18 July 2000 13:34
To: 'classiccmp(a)classiccmp.org'
Subject: RE: Repair or Replace? [Was: Repairing Timex]
Surely any serious computer hobbyist, especially
one who is a
collector or preservationist, has at least the following: DVM,
oscilloscope (even if just an old 5mHZ one to look for
things like PSU
ripple/spikes), soldering iron, logic probe,
assorted hand tools and
perhaps a logic analyzer. These are not things that the
average hobbyist
should be unlikely to have.
I guess I got spoiled by working at the university and at a local
electronics trade school, and then later for a small embedded systems
firm. I almost always had a scope of someone else's available to use.
Now I don't, and I regret not picking up a dual-trace 15 or 20mHz
scope when I'd see one available, cheap, from time to time.
My favorite was the Tektronix storage display scope. Now, I just
try to get by using a Rat Shack logic probe and a DVM. Plenty of
soldering irons (one Ungar, one generic one-piece, one Wahl), and
various hand tools. A manual wire-wrap pen somewhere. A CSC bread-
board. A fair selection of components, new and used.
-dq
18 Jul
18 Jul
9:03 a.m.
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11:54 p.m.
New subject: Repair or Replace?
Incidentally, an analogue multimeter can be more use
than a digital one
for some work. It's a lot better at showing trends, indicating when the
amplitude of a signal is peaking, etc. Accuracy is not that important in
most repairs -- certainly +/-5% is easily good enough for most work.
I still have my big Simpson VTVM, but one of the surplus joints in town has
a bunch (dozens) of HP (I think) FET versions, the ones that used to be so
common in labs about 8" tall, 5" wide, and maybe 5" deep with a nice wide
mirror scale etc. Any sane reason I should get a few of them?
19 Jul
19 Jul
4:03 a.m.
New subject: Repair or Replace?
On Wed, 19 Jul 2000, Mike Ford wrote:
Yes. The simpson is an excellent meter but it is a VOM and it places a
load on the circuit under test of 20,000*(volts scale in use). Some
circuits don't like this and a fet VM presents a high resistance load
(11megohms typical). It's worth having, especially if they are cheap.
Allison
Incidentally,
an analogue multimeter can be more use than a digital one
for some work. It's a lot better at showing trends, indicating when the
amplitude of a signal is peaking, etc. Accuracy is not that important in
most repairs -- certainly +/-5% is easily good enough for most work.
I still have my big Simpson VTVM, but one of the surplus joints in town has
a bunch (dozens) of HP (I think) FET versions, the ones that used to be so
common in labs about 8" tall, 5" wide, and maybe 5" deep with a nice wide
mirror scale etc. Any sane reason I should get a few of them?
4:06 a.m.
New subject: Repair or Replace?
On Wed, 19 Jul 2000, Mike Ford wrote:
I still have my big Simpson VTVM, but one of the surplus joints in town has
RE: my last... I saw simpson and though simpson260 which is one of the
best VOMs on the market. You have The VTVM? That is an 11Megohm meter
though the fet one will require less calibration and warmup. Also being
HP it's built like a tank!
Allison
8770
days inactive
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4 comments
4 participants
participants (4)
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agraham＠ccat.co.uk -
allisonp＠world.std.com -
ard＠p850ug1.demon.co.uk -
mikeford＠socal.rr.com