# Testing DC/DC Converters

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#### Nick Naylor

Jan 1, 1970
0
Greetings All,

I'm looking for a way to repeatedly test DC/DC Converters. The
largest consideration is wear. I currently use little gold terminals
that the pin slides into. It actually has a little spring in it.
These are high current pins, but once they wear out, the connection
gets very weak and I lose a good amount of voltage because of it. My
goal is to have a repeatable test setup that will not wear. One
requirement is high current, the other is high voltage. Does anyone
work with this sort of thing? Any suggestions?

I

#### Ian Stirling

Jan 1, 1970
0
Nick Naylor said:
Greetings All,

I'm looking for a way to repeatedly test DC/DC Converters. The
largest consideration is wear. I currently use little gold terminals
that the pin slides into. It actually has a little spring in it.
These are high current pins, but once they wear out, the connection
gets very weak and I lose a good amount of voltage because of it. My
goal is to have a repeatable test setup that will not wear. One
requirement is high current, the other is high voltage. Does anyone
work with this sort of thing? Any suggestions?

T

#### Tim Wescott

Jan 1, 1970
0
Nick said:
Greetings All,

I'm looking for a way to repeatedly test DC/DC Converters. The
largest consideration is wear. I currently use little gold terminals
that the pin slides into. It actually has a little spring in it.
These are high current pins, but once they wear out, the connection
gets very weak and I lose a good amount of voltage because of it. My
goal is to have a repeatable test setup that will not wear. One
requirement is high current, the other is high voltage. Does anyone
work with this sort of thing? Any suggestions?

I do not work with this, but the concept of ZIF sockets as used in IC
testers and programmers springs to mind. I've only seen them for IC
packages -- I have no idea of whether other sizes of these are available
on the open market or if you'd have to make your own. At least with the
pin sizes and spacings of the average DC-DC brick you're talking about
something bigger than the usual chip.

There's another thread on this group that mentions fretting corrosion
when you mix gold and tin contacts. I imagine that your converter pins
are tin plated; you may be having similar problems with your contacts.

F

#### Frithiof Andreas Jensen

Jan 1, 1970
0
Nick Naylor said:
Greetings All,

I'm looking for a way to repeatedly test DC/DC Converters. The
largest consideration is wear. I currently use little gold terminals
that the pin slides into.

Assuming it is the 'test-side' that is the concern:

Make the test connectors easily replacable ;-)

Most connectors are only guaranteed to be usable for a very small number of
cycles. About 400 is the highest I ever saw promised - and that was for
those round "wire-cage" thingies which-i-cannot-remember-the-name-of in an
Aerospace application I.E: .

T

#### Tony Williams

Jan 1, 1970
0
................. - and that was for those round "wire-cage"
thingies which-i-cannot-remember-the-name-of in an Aerospace
application I.E: .

"Hypertac", a French patented connector afair.

We used to use them in moderate quantities and, as you
say, big bucks.... even for minor piece parts, such
as the indexing socket-nuts.

Their big deficiency was that they were not neccessarily
self-aligning, so you had to be very careful to ensure
that all pins were centred in their sockets before winding
up the jacking screws..... otherwise bent pins.

A stock of spare contacts and a contact extraction tool
(more big bucks) was an absolute neccessity for anyone
using Hypertacs.

R

#### Rich Grise

Jan 1, 1970
0
"Hypertac", a French patented connector afair.

We used to use them in moderate quantities and, as you
say, big bucks.... even for minor piece parts, such
as the indexing socket-nuts.

Their big deficiency was that they were not neccessarily
self-aligning, so you had to be very careful to ensure
that all pins were centred in their sockets before winding
up the jacking screws..... otherwise bent pins.

A stock of spare contacts and a contact extraction tool
(more big bucks) was an absolute neccessity for anyone
using Hypertacs.

I've seen military connectors that were designed, or at least
specified, to accommodate multiple insertions, and are self-
aligning, as a unit. The socket side is attached to the airplane
chassis, and a piece of avionics slides into the slot and the
plug on its back panel mates with the socket on the airframe.

This was military, and so no doubt prohibitively expensive.
Then again, I never saw any insertion/extraction life cycle
figures, so for all I know, 400 might be optimistic.

So what then springs to mind is something very similar to
a standard "zero insertion force" IC socket, which has a
lever that has to be moved to the other position to open
or close the contacts. Each contact on the socket side is
like a miniature clamp, and the lever actuates them all
simultaneously. The test piece can literally be dropped
into the socket. For a big high-current, it's almost a
natural to extend this to a kind of "socket" that's, say,
a small array of "lower jaws," around a spot to drop the
DUT, which has tabs that lie on the lower jaws, and when
you mmove the lever, the "upper jaws" of all of these
contacts close around them. With a little compliance
built into the contacts, some wiping action could be
achieved without scraping all the gold off the contacts
within your first few dozen test parts.

Hope This Helps!
Rich

T

#### Tony Williams

Jan 1, 1970
0
Rich Grise said:
So what then springs to mind is something very similar to
a standard "zero insertion force" IC socket, which has a
lever that has to be moved to the other position to open
or close the contacts. Each contact on the socket side is
like a miniature clamp, and the lever actuates them all
simultaneously.
[snip]

That is more or less a description of the Cannon ZIF connector,
used widely in avionics test rigs. Very expensive, (about
GBP250 for a complete 156-way plug/socket pair), but it is
reliable over 100's of plug/unplug cycles.

L

#### legg

Jan 1, 1970
0
Greetings All,

I'm looking for a way to repeatedly test DC/DC Converters. The
largest consideration is wear. I currently use little gold terminals
that the pin slides into. It actually has a little spring in it.
These are high current pins, but once they wear out, the connection
gets very weak and I lose a good amount of voltage because of it. My
goal is to have a repeatable test setup that will not wear. One
requirement is high current, the other is high voltage. Does anyone
work with this sort of thing? Any suggestions?

Manual insertion will result in shorter life of most test bed
connections. It's important that the materials in pin and socket are
compatible.

For simple, fast, functional testing, pogo contacts are usually
better, though measurement and power test points have to be isolated
(by kelvin arrangement of multiple contacts) for repeatability. These
don't always have to be on the terminals supplied to the end user - ie
power from below, measure from above - unless these are the only
access points available.

For burn-in, there is no real choice but to use a similar hardware
arrangement as is expected in end-use, with suitable life-cycle
rotation and budgeted scrap/refurbishing of life-limited parts.

Test hardware is something that has to be anticipated in a product's
design and development budget.

If you are re-testing someone elses product, perhaps you could
negotiate appropriate test and documentation by the mfr prior to
purchase/ship.

RL

G

#### Guy Macon

Jan 1, 1970
0
Frithiof said:
Most connectors are only guaranteed to be usable for a very small number of
cycles. About 400 is the highest I ever saw promised - and that was for
those round "wire-cage" thingies which-i-cannot-remember-the-name-of in an
Aerospace application I.E: .

On the contrary, ODU-Springtac connectors are good for over a million
connect-disconnect cycles.

See [ http://www.odu-usa.com/detail.taf?rowid=169 ].

N

#### Nico Coesel

Jan 1, 1970
0
Greetings All,

I'm looking for a way to repeatedly test DC/DC Converters. The
largest consideration is wear. I currently use little gold terminals
that the pin slides into. It actually has a little spring in it.
These are high current pins, but once they wear out, the connection
gets very weak and I lose a good amount of voltage because of it. My
goal is to have a repeatable test setup that will not wear. One
requirement is high current, the other is high voltage. Does anyone
work with this sort of thing? Any suggestions?

You can use a pin-saver on the test fixture. This is usually a male
and female connector connected back to back.

G

#### Guy Macon

Jan 1, 1970
0
Nico said:
You can use a pin-saver on the test fixture. This is usually a male
and female connector connected back to back.

I worked on an aerospace project where the spec called for replacing
the connector after the third disconnect. two connector savers went
on the male and female connectors and were removed right before final
boltdown of the access hatch and final system test.

B

#### Boris Mohar

Jan 1, 1970
0
Greetings All,

I'm looking for a way to repeatedly test DC/DC Converters. The
largest consideration is wear. I currently use little gold terminals
that the pin slides into. It actually has a little spring in it.
These are high current pins, but once they wear out, the connection
gets very weak and I lose a good amount of voltage because of it. My
goal is to have a repeatable test setup that will not wear. One
requirement is high current, the other is high voltage. Does anyone
work with this sort of thing? Any suggestions?

You need these

http://www.hypertronics.com/

Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs http://www3.sympatico.ca/borism/