View Single Post
  #3   Report Post  
Posted to sci.electronics.repair
Arfa Daily
 
Posts: n/a
Default Blown caps in DVD player


"Sam Goldwasser" wrote in message
...
Nospam writes:

Have a DVD5052M DVD player that was powered up when it was found to be
dead. Power checked was ok, last used a couple of months ago. Opened and
found two caps had exploded with contents/foil spread across SMPSU
board. Likely that I can identify them from the remains so as to replace
them.

Question is in view that power was still on (fuse appears ok) and the
foil found between other components what is the likely hood that
replacement of the caps would restore functionality or would it be more
likely that other damage has occurred?

If repair is considered feasibility, apart from replacement of one with
a slight bulge on the top what other checks can I carry out on in situ
caps?


Check semiconductors for shorts, low value resistors for opens, and wish
yourself luck. If it's like the one I just repaired that had a bulging
high ESR cap, there are only a very few semiconductors, maybe an 8 pin
IC that's the actual switching component.

See the SMPS repair guide at the site below.

If the power supply unplugs from the DVD mainboard, it might be worthwhile
to test it first with dummy loads to make sure it's properly regulating
once the bad parts are replaced.


It's quite common on ' cheapies ' that when the caps initially start to
fail, the supply rails go up to way beyond what they should be. This is due
to the voltage regulation feedback that's often used on these switchers.
When this happens, it almost invariably does damage to the LSI's on the mpeg
board. In my experience, you've got about a 50-50 chance, depending on the
regulator circuitry employed. Replacing the caps will almost certainly
restore the PSU to working, but don't hold your breath that the rest of the
machine will then work.

Arfa