[R-390] HP410B Intermittent(s) and solder joints

[Patrick]

Have a MFJ-929 Automatic antenna tuner that the circuit board where all the 
switches go, was covered by some sort of film, about half of solder points 
of the 8 switches (6 contacts each) never made contact with the board, GREAT 
QUALITY CONTROL BY MFG, after considerable ammount of work removing all the 
switches, scraping the board contact points and resoldering the switches, 
the tuner has performed great.  Pat

Joints some time do get cold with age, I know, my knees and hips are cold.

----- Original Message ----- 
From: "Jon Schlegel" <ews265 at rochester.rr.com>
To: <r-390 at mailman.qth.net>
Sent: Monday, May 25, 2009 1:37 PM
Subject: Re: [R-390] HP410B Intermittent(s)


> Don,
>
> Finally got all the flakies fixed, calibrated the instrument and the
> 410B now works great.  It was just surprising to see the
> as-manufactured poor solderability of the terminal boards.  It took a
> lot of effort to find everything.
>
> The 122 Megohm input Z is quite the thing.  Just moving my hand near
> the probe zooms the meter pointer around quite a bit.
>
> Jon
>
>
> P.S. The Youtube clip is quite the culture shock!
>
>
>
>
> At 12:13 PM 5/25/2009 -0500, Don Reaves wrote:
>
>> > get go.  Removing the old gucky solder then liquid flux and heat
>> > seemed to give a ok joint.  It was surprising to see that kind of
>> > problem inside of an HP instrument.
>> >
>>
>>Not unheard of.  I once found the problem with an HP-200R with 
>>intermittent
>>output to be that a b+ line leading from the power transformer had never
>>seen a hint of solder.  The wire was wrapped on the transformer solder 
>>lug,
>>and it probably worked OK for a few years, then slowly oxidized.
>>
>>A slight variation of the Stockdale technique to restore operation of a
>>BC-375 worked on the HP-200, before the proper repair was implemented.
>>
>>http://www.youtube.com/watch?v=TBXmVqcAP6M  (at about 2:30 in this clip)
>>
>>
>>Don
>>
>>
>>______________________________________________________________
>>R-390 mailing list
>>Home: http://mailman.qth.net/mailman/listinfo/r-390
>>Help: http://mailman.qth.net/mmfaq.htm
>>Post: mailto:R-390 at mailman.qth.net
>>
>>This list hosted by: http://www.qsl.net
>>Please help support this email list: http://www.qsl.net/donate.html
>
>
> ______________________________________________________________
> R-390 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/r-390
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:R-390 at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html 


-- 
I am using the free version of SPAMfighter.
We are a community of 6 million users fighting spam.
SPAMfighter has removed 2597 of my spam emails to date.
Get the free SPAMfighter here: http://www.spamfighter.com/len

The Professional version does not have this message