[time-nuts] HP 5370A socket problem

[Chuck Harris]

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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