14 June 2012

Removing the filter case without desoldering it from the PCB

Desoldering the ceramic filters in order to fix them can be a tough proposition in many cases. So, I came up with a different way of removing the plastic case - without removing the filter from the PCB..
Take a look at the picture (it's from the repair of an TM-D710E). Using long nosed pliers, grab the filter case exactly as shown and, gently but firmly, pull the case by - very carefully! - rocking the pliers in the direction of the red double arrow (perpendicularly to the longitudinal axis of the filter). The case usually comes off relatively easily and the offending elements can then be easily inspected, removed and cleaned, restoring proper filter function. Be careful not to lose the bronze tensioner spring plate that (usually) comes off with the case. This method of case removal has worked every time for me (I have fixed more than 50 filters up to now), saving me considerable time and work. Of course, after repairing the filters, don't forget to add the DC blocking capacitor at the output side of each filter, so that you won't have to remove the filter case again!

***ADDENDUM: Carefully heating around the base of the filter case for a few seconds with a hot-air soldering gun set at about 200 degrees Celsius usually makes the case come off much more easily. I said "Carefully", please take note!