From: pcdhSpamMeSenseless@electrooptical.net   
      
   Cursitor Doom wrote:   
   > Hi all,   
   >   
   > So my main analogue scope, a Tek 2465A, has gone faulty. Keeps blowing   
   > main fuses (the 2A one on the rear panel). I opened the case and found   
   > two RIFA caps that had obviously blown, so replaced them, but it's   
   > still blowing fuses. I can't be 100% certain, but I'm pretty sure   
   > there's a fault with the PSU board as I get the briefest whiff of   
   > burning from that area each time I put a new fuse in and power up. The   
   > new fuse blows again before I get to see any smoke coming from   
   > anywhere at all. I'm linking to a diagram of the PSU as I'm not   
   > familiar with this circuit topology. If anyone can spot a component   
   > here that could have gone low-resistance and might be a good candidate   
   > for out-of-circuit testing, by all means let me know.   
   > Thanks,   
   >   
   > CD.   
   >   
   >   
   > https://disk.yandex.com/i/UhxATIy-6Y0LIA   
   >   
      
   Yikes.  When a fuse blows, you replace it *once*.  If it blows again, it   
   ain't the fuse or a line transient.   
      
   Start with a DMM and check for shorted diodes in the input bridge and   
   then for a shorted filter cap at its output.  (The schematic is more or   
   less completely illegible, or I'd give the ref des.)   
      
   Next most likely is a switch FET.   
      
   Cheers   
      
   Phil Hobbs   
   (proud owner of a 2467 that he almost never uses)   
      
      
   --   
   Dr Philip C D Hobbs   
   Principal Consultant   
   ElectroOptical Innovations LLC / Hobbs ElectroOptics   
   Optics, Electro-optics, Photonics, Analog Electronics   
   Briarcliff Manor NY 10510   
      
   http://electrooptical.net   
   http://hobbs-eo.com   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)