On Friday, May 8, 2009 5:25:43 AM UTC-4, Arfa Daily wrote:
wrote in message
...
I have a one year old Emerson LCD TV/DVD combo model # LD200EM8
Dead set, I found AND replaced the following faulty parts in the SMPS
section:

*shorted MosFet switcher transistor on primary Q601 2sk3563
*shortet "fast" diode on secondary D901
*open line fuse 4 amp GMA
*shorted zener diode on primary D624 (39 volt, I think)

Note: It is hard to read the markings on the burnt zener D624, I
"think" it is a 39 volt zener, MTZJT-7739B, although it might be a 33
volt MTZJT-7733B instead, or something different, can anyone confirm
the correct voltage?

I have tried to power up the unit and NOTHING. None of the parts I
replaced were damaged, I have primary B+ but nothing else. What have
I missed on this single board chassis? Anyone having experience and
a diagram on this unit would be most welcome.
Any repair ideas from you smart people out there????
Common "dead set" issues with this unit? Help.
thanks,
electricitym

Have you tried ESR checking all the electrolytics on the primary side ? Is
this a 'typical' LCD power supply that has effectively three SMPSs on the
same board ? ( PFC supply, standby supply and run supply) If so, is the
standby supply running ? I repair a lot of LCD switchers, and sometimes,
they can be very difficult to get going again. One little trick on an
'unknown', is to cast around on the 'net to see if there is a "PSU repair
kit" available for the model. If there is, it is often worth investing in
one, and fitting ALL of the parts which come with it, irrespective of
whether they look / read / don't seem to be faulty. Almost always, this will
result in a long term fix. By doing this, you eliminate the uncertainty of
interpreting 'ambiguous' markings on tiny surface mount components.

Most modern switchers are quite well behaved repair wise, when you fit a
genuine repair kit. After using such a kit, you can file away the parts list
that comes with it, and next time you get one in for repair, you can source
the individual parts cheaper than buying a kit.

Arfa

Trying to fix a 32" RCA TV DVD Combo. model # RLCDV3282A-B.

When I plug in the TV does not turn ON. However a dim power light (RED led) comes On.

No clicking sound. No buzzing. Nothing. Plain and simply dead except for the dim POWER light.

I am unable to locate specifically the bad component.

Checked most capacitors. No visible signs of damage or bulge.

Across the main 450v 68uF capacitor I get 90v DC. Mains has steady 110V AC.

Output connectors of the main power supply board gives 24, 12 and 5 v DC. No problems.

However, the DVD board is not getting its 5 volt DC which actually comes from the main-board that has the graphic ic and all other video ouput connectors like HDMI etc.

I am unable to trace where/why the 5 volts from this board is NOT coming to the connector. There is another set of long connector on this main board which receives power from the power supply and that shows the relevant 12v and 5 v Dc at that point.

So in short, the main-graphic board that also powers the dvd is not giving 5v dc output to the DVD player - which i believe also powers the switches - and thus the TV is perhaps frozen in standby mode ( I am not sure of that) No remote so I cannot take it out of the standby mode - also ALL the switches are non responsive.

Any help will be appreciated.