Re: Help with strange audio fault #qcx

Alan <g8lco1@...>

Freezer spray may help, the condensate is not a problem   excepting on high voltages  or very high impedance circuitry which are not present here.   But a cleaner, cheaper  and more certain method is to use a paintbrush on the solder side of the pcb to put gentle pressure on every solder joint looking for the joint where a good bond has not been made.  Use the brush ( a ½” paintbrush works well on small boards) brushing across the board and note the location where things change then work up and down to home in on the bad joint. I have used this method for around 30 years, it has always worked for me in locating dry or unsoldered  joints and intermittent connectors. 


If the brush is too soft then trim the hairs down to ½” long, long enough to keep the metal ferrule well clear of components. You need a ½” or 1” wide home decorating style brush  with stiff  hairs not a  small artist’s Brush, you need to displace the faulty joint not paint it! If you are worried about the ferrule shorting parts then apply a few turns of insulating tape to the ferrule.


The freezer spray is really best for finding intermittent faults INSIDE IC’s where there is a bond wire issue internally. This class of fault is extremely rare these days but was more common many decades ago.






Sent from Mail for Windows 10




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