EEVblog Electronics Community Forum
Electronics => Repair => Topic started by: peteb2 on October 11, 2018, 09:19:29 pm
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By way of a tangled path an item comes to you because "i hear you can fix gear'. The story unfolded the unit (a sound process device) had stopped working suddenly after the power supply electrolytic capacitors had already been changed by another tech and that had let it work for a few more weeks but now it'd gone dark....
So you have a look and soon find the switchmode has another nasty little issue. It's covered in gobs of assembly goo that has plainly turned brown and become conductive. It's an unusual module with +/-15V, 5V & 3.3V with integral IEC mains connection socket.
So here was my mistake: Taking at face value from the owner's assurance the unit actually, truly, really worked.... FULLY. In a proper world i would have set up my own set of supply voltages and made sure there wasn't any chance of a gotcha.... I didn't .... (so there's your reminder for the day).
Instead i spent a couple of hours on the SMPS , removing parts & scratching away the conductive goo and then soldering them back in place. Even the output loom had been coated in the goo and the strands of wire were corroded from the it so nipped the ends and re-terminated everything.
So finally i'd a fully working SMPS with proper clean voltages but powering up the unit ... oh dear. The display lights, selections can be made but it doesn't do a thing. It can't even be programmed .... and the owner says now they just gonna buy something new....
And so there's your second reminder.... Make 100% certain the party whose bought you a 'thing' to fix because they're 'desperate' understands exactly what your deal is and what to expect or you are simply gonna be the loser.... (on this one i get to have a bleat here).
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Sounds like a case of "Beyond economical repair"? Can be hard to spot without digging a little, of course.