Need help with Mitsubishi ws-48313

[Bob]

I have a mitsubishi ws-48313 48" tv that only has the power light come
on when plugged in. I figured it was the common dm module capicator
problem. Turn's out it has no dm module so thats not it. I used my
cap checker and have found no bad caps yet. Also checked all the
fuses and none are bad. Does anyone with experience on these sets
have any suggestions on what to look at next. I googled the set but
found no info. I purchased the service manual but it hasn't arrived
yet.

Thanks

 

In that unit, it is likely that the SMPS chip is not starting up.
Let's put it this way, if any part of it is not running, if any part
of tit does it will probably shut down, and the light would go off or
start flashing or something.

Your mission at this point if you are getting nothing is to find the
main raw AC rectifiers and the main filters. Now I have seen
Mitsubishis as well as other brands that put the bleeder on the wrong
side of the filters, which means that 940uF could still be charged to
130 voltas after a week. I have had it happen.

You get a table lamp, a REGULAR ONE, that plugs into the wall, has
like a 60 watt bulb in it, the old regular kind, none of this new
fancy shit. Bend the blades together just a bit and touch them, on the
bottom of the PC board where the terminals for the main filters are.
And discharge them with a light as I described NOT a screwdriver !
That is so unprofessional I might not even do it my own set.

Anyway, if you don't find that voltage on the SMPS transformer
primary, you can change the chip, but unless you discharge the filters
you might get hurt, because you will have to change the blown fusible
to it. I't easy to find, but there might be a load of voltage on one
side.

But then if the chip went open (which they do) you will have that
voltage at the IC pin. You do NOT want that big spark as you are
desoldering the IC, that will destroy many perhiperal components.
Unproductive. You really must discharge.

I've been in this business almost 30 years and I do it that way. We
had a discussion about 220V lightbulbs for the overseas stuff, but
thusfar it is all voltage doublers, so I just discharge the caps
seperately. Works fine.