Next!
So I settled into my comfortable chair this morning to enjoy light discourse over fresh coffee with JTS when
a Total utter hold-the-front-page earth shattering electronic emergency occurred. 
<- haven't seen that one in a while....This stopped working...
Its a 24V DC PSU that powers the recline function on my chair. That means I can't recline into the usual 'intense-music-listening/resting-my-eyes' position.
A LOCAL STATE OF EMERGENCY WAS DECLARED.
On to the bench for pronto fault finding. I found the glass envelope of the T3.15A fuse soldered by end-caps to the PCB by the mains power connections physically blown apart. This didn't bode well, a fuse that size blowing in that fashion points to big instantaneous current draw, oddly I couldn't measure any low resistances but it was very difficult to visually check for signs of arcing or heat damage as a lot of the components were covered in a silicone rubber solution. Hmm, I chanced a temp replacement 20mm fuse wired into a makeshift fuse holder then carefully powered up to observe for localised lightning.
Not unsurprisingly, Erks..
Saw summat close to the heatsink flash before the fuse blew again although there were no low resistances found around the semiconductors in that area, odd. I started hacking away at the white silicone sealant gloop....
I found this NTC device blasted in two, (featuring special manicure detailing for our-Simon)....
...and further signs of arcing where a hole has been blasted through here as illustrated by the pointer...
Aha! Found it. One leg of the big electrolytic cap has fractured and you can see where arcing has flashed across the pinout area of the cap...
Right, thats too many safety critical components popped there for my liking so I'm not going to go further with a possible repair here so I'll order a replacement PSU.
In the meantime a handy bench PSU is supplying my chair tonight.
And relax
.
