Molex connectors are very inexpensive, quick to assemble, sold everywhere,
come in a very large variety of sizes and pin configurations, and keyed to
prevent insertion errors.
If their current rating degrades that would be with hundreds or thousands of
insertions, and that is not relevant in this case since Wolfgang will be
connecting and disconnecting them a few times at most. A 17Amp rating is so
much higher than any current inside a Tek Scope that even if they were to
degrade that won't affect their ability to work correctly in a scope or
curve tracer. The only exception might be with the 576 High Current Adapter
which uses Kelvin connectors to prevent a voltage drop from interfering with
accurate measurements.
If there is a more reliable connector that you have come across I could
always use them in my designs. So if you can point me to them please do.
Dennis Tillman W7PF
toggle quoted message
Show quoted text
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Harvey
White
Sent: Tuesday, November 13, 2018 7:13 PM
Subject: Re: [TekScopes] Curve Tracer 577 - Power Supply Overhaul
On Wed, 14 Nov 2018 07:33:38 +1000, you wrote:
Ok thanks, Dennis, for that heads-up. I looked-up "Molex" instantly
slightly embarrassed then as I do know them, but not by that name
I've occasionally had problems with them, maybe half a dozen, when I
had an automotive business. Only seemed to be one pin each time and
maybe once or twice on transceivers so they are pretty reliable. Yes,
that rating sounds good for Wolfgang's purposes, as you say.
I've heard that they are not the most reliable. That will suggest that at
least for most purposes, don't connect and reconnect them a lot.
On the current ratings, from what I understand, the current rating is
good,
but goes down with the number of insertions.
I suppose Wolfgang's intervening with them now is as good a time as
any, if going to be done. I suppose the other ones of which he speaks
are those small ones Tektronix uses to clip into my
425....+/- same as in computers...
My feeling on the tektronix connectors is that they were never designed
for
continuous (as in we're debugging this) connects/disconnects. Look at the
ratings on FPC connectors, which are as little as about 20. These are not
necessarily the same, but it does suggest that tektronix was intending
these
connectors for board replacement and disassembly, and not the same duty
cycle as the connectors for the 7000 series plugins were designed for.
The more I read on the site, irrespective of whether I ever use
it...the more I learn and 'snap-out-of -it' I haven't had to think
about electronics much for several years, but now when completely
rebuilding my test equipment, (5 units done in last fortnight) and
determined to get my 425 on the road, hopefully in a week or two and
maybe the 564 Then with at least 7 WW11 Rx's, ART-13 and seven Rx's
(Drake /Yaesu) a globe 303 and its VFO to rebuild ...I have to get
back into that mind-space.
You've got a hobby. Welcome to the club.......
I guess focussing on
Tektronix CRO's helps one into Tektronix' design mindset and that
benefits to some degree, working on each of the various models.
True, and they designed and built lots of other stuff.
From what "we" are likely to find, oscilloscopes, then maybe
TM5000/TM500 stuff, then perhaps spectrum analyzers (7L series). You
could
argue it from there.
Harvey
-----Original Message-----
From: Dennis Tillman W7PF
Sent: Wednesday, November 14, 2018 6:37 AM
To: [email protected]
Subject: Re: [TekScopes] Curve Tracer 577 - Power Supply Overhaul
Hi Jack,
According to the specs the 0.093" Molex pins are rated for 17Amps so
there is no problem with current or voltage drop.
Dennis Tillman W7PF
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of
Jack
Sent: Tuesday, November 13, 2018 11:00 AM
To: [email protected]
Subject: Re: [TekScopes] Curve Tracer 577 - Power Supply Overhaul
In a general sense Wolfgang, as I am not a specialist with
Tektronix...wiring p/s directly to the pcb may simply have been an
assembly convenience.
Factory introducing of connectors along the way for other leads may
be to increase technician convenience and reduce possible damage
during board service or replacement and to make easier the
assembly-line
wiring.
I can't see a technical reason against intervening in the power
supply lead situation particularly if you do not have to unsolder
from the board.
Although I have no experience with the connectors you mention I
wonder whether power supply current could adversely heat them?;
otherwise as there here is no insertion loss or voltage drop enough
to concern you...mains supply variations would provide a greater
'drop' than such intervention as you are considering. Safety from
transformer voltages during service might be reduced by any exposed
connection 'along the way' to the pcb...again, I am generalising.
My Regards
--
Jack
--
Dennis Tillman W7PF
TekScopes Moderator
--
Dennis Tillman W7PF
TekScopes Moderator
