[Test-Equipment] HP410B - Resistor Board Solder Question

[WA5CAB--- via Test-Equipment]

Barry,

I don't know anything about working on the 410 so don't know the answer to 
your silver question.  However, as early as about 1980 I began to notice 
that early WW-II vintage solder joints were a lot easier to deal with (easier 
to get the old solder to flow) if rather than just heating the joint, I also 
added a little new solder.  I don't know whether it was because of the new 
solder or the new flux, but hard to melt joints became much easier to melt by 
doing this.  Equipment made in 1975 is now at about the same 40 year age 
point.  Note that this had nothing to do with MFP, which I had learned long 
before 1980 to remove before trying to do anything else.

Robert Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480

In a message dated 10/11/2014 20:06:43 PM Central Daylight Time, 
n4buq at knology.net writes: 
> Working on refurbishing an HP-410B and am replacing the old carbon 
> composition resistors with more modern, higher wattage resistors.  I unsoldered 
> the first 4 or them, but had a really hard time getting the solder to melt 
> and getting the leads out.
> 
> Is it possible this is silver-bearing solder?  It seems a bit harder to 
> melt and doesn't quite flow the same as good ole 60/40.  If it is 
> silver-bearing, I wonder if I need to stick with that (I don't have any of that)?  I 
> know that on other devices (Tektronix scopes come to mind) that the material 
> used on the connection itself is silver/silver-plated and needs 
> silver-bearing solder; however, I assume the traces and/or through-hole ferrules are 
> not silver on this board (could be, though).
> 
> Anyone else run into this?  I think I've replaced some of these on another 
> 410B I had and don't remember running into this problem.
> 
> Thanks,
> Barry - N4BUQ