IBM 5155 analogue display fault

Dwight K. Elvey dwight.elvey at amd.com
Thu Jun 2 19:21:15 CDT 2005


>From: jpero at sympatico.ca

>> > > But PCB tracks can be easily un-cut -- just solder a piece of wire
>> > > over the break. Wire-wrap wire (stripped, of course) is ideal for
>> > > this.
>> > > 
>> > 
>> > Yikes!
>> > 
>> > I am the guy who in the past has had to figure out what the HECK is
>> > wrong with a board, where somebody 'just tacked a piece of wire along
>> > the track.'  Such forms of modification/repair often _disguise_ a wiring
>> 
>> I have _never_ had a problem doing  this (read : I've never had such a 
>> repair fail, even after <n> years). Now a blob of solder across a break 
>> will _not_ hold, you must put the wire there.
>> 
>> I typically put at least 1/2" of wire on each side of the break and 
>> solder it down.  
>> 
>> -tony
>
>Yikes?   I do this for TV/Projector, PC boards all the times on 
>tracks that comes off for any reason, bridge cracked PCB etc.   I 
>scrape off mask and polish it with eraser rod and lay sized and cut 
>to length if needed pre-shaped to follow the bends in the trace and 
>solder.
>
>This repair method is stronger.
>
>Cheers,  Wizard
>

Hi
 Medical equipment standards are a little different than what
we do. I also do this type of repair and consider it more
than adequate. There are several problems though. First is
that if one scrapes the plating off to bare copper, a solder
to copper joint ages to form a high resistance connection.
This is increased by temperature ( mostly a problem in high
power locations and old tube circuits ). The other reason is
that such joints are sometime difficult to verify if the
solder was properly done, especially when the wire is large
compared to the trace.
Dwight





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