[time-nuts] HP 5370A socket problem

[Robert Atkinson]

Hi,
I've not seen socket problems on my 5370B, but have with other equipment. The TI leaf contact sockets seem to be the worst. I've often wondered if it's a plating compatability issue. Small differences in plating composition might be causing problems. Retention force is not an issue as noted, but high retention could be caused by corrosion. Often just shifting the IC's in their sockets will effect a short term cure. For a cheap (slightly)longer term fix, wipe the IC pins with a swab moistened with WD40! 

Robert G8RPI.

--- On Wed, 20/5/09, Chuck Harris <cfharris at erols.com> wrote:

> From: Chuck Harris <cfharris at erols.com>
> Subject: Re: [time-nuts] HP 5370A socket problem
> To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
> Date: Wednesday, 20 May, 2009, 5:06 AM
> Hi Didier,
> 
> I have never doubted for one moment that the sockets were
> causing
> your problems, I just wonder how prevalent the failure is
> in the
> universe of 5370's.  I have HP equipment that is both
> newer and
> older than my 5370A, that has the same sockets.  It
> would not
> surprise me at all to find the 5370B has the same exact
> sockets
> too.
> 
> Double sided boards are a treat to work on with
> desoldering
> equipment.  Multilayer boards suck up so much heat
> that they
> are a real problem.  It helps to cook them on an IR
> preheater for
> a while before removing parts.
> 
> -Chuck Harris
> 
> Didier wrote:
> > Hi Chuck,
> > 
> > I agree, I could not see anything obvious that would
> indicate these
> > particular sockets would cause problems, other than
> they certainly looked
> > cheap, even considering the date of manufacture. The
> contact pressure was
> > quite considerable, based on how hard it was to pull
> the chips out, so it
> > probably was not a bad contact between the socket and
> the pins. There are a
> > bunch of chips on sockets, and I never tried to find
> out if a particular
> > chip was causing the problem. I replaced all the
> sockets (except the PAL, I
> > did not have a socket for him.)
> > 
> > The good news is that the PWB has very thin traces
> (requiring little heat),
> > and the holes are fairly wide, so unsoldering the
> sockets was a piece of
> > cake, with the right tool. I did each unit in about 30
> minutes, all
> > included. The easiest was to remove the plastic part
> of the socket BEFORE
> > unsoldering the contacts. It comes off easily when you
> pull on it. Then each
> > contact can be removed individually with minimum
> stress on the board.
> > 
> > One of my two units had evidence of having been in
> uncontrolled storage for
> > at least some time before I got it. The case was very
> dirty, inside the unit
> > was dusty but relatively clean. The other was
> relatively clean inside and
> > out.
> > 
> > One thing for sure, is that until I replaced the
> sockets, the units would
> > only work a few days at a time, and wiggling and
> reseating the PROMs would
> > fix the problem each time, until next time.
> > 
> > Didier
> > 
> >> -----Original Message-----
> >> From: time-nuts-bounces at febo.com
> [mailto:time-nuts-bounces at febo.com]
> On Behalf Of Chuck Harris
> >> Sent: Tuesday, May 19, 2009 7:52 PM
> >> To: Discussion of precise time and frequency
> measurement
> >> Subject: Re: [time-nuts] HP 5370A socket problem
> >> 
> >> Hi Didier,
> >> 
> >> I just had a look in mine, and it uses plain old
> TI sockets.  They may, or may not be gold (I didn't
> look that carefully).  My unit is S/N 2217A01399, so it
> sits in the middle of your two units.
> >> 
> >> I know that my unit is special (because it is
> mine, of course ;-), but I just don't think it is all *that*
> special.  I have seen the same TI sockets used on so
> many different instruments --I would bet more than half the
> stuff in my shop has them--  They seem to work more
> often than not.
> >> 
> >> -Chuck Harris
> > 
> > 
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