Emerson hdtv troubleshooting

[selldoor]

Re: Emerson hdtv troubleshooting

OK need test no more in that area 160.8 on Big cap is a good start.
Its late here so hopefully others will pick up now.

[ddarn]

Re: Emerson hdtv troubleshooting

yes hopefullly..

[selldoor]

Re: Emerson hdtv troubleshooting

No-one eh!
ok using just that power board just carefully check again the VDC on that main cap.

If that is still there set meter on 200vdc and at various places on the board there are wire jumpers that have a voltage marked on them. Stay out of the primary Hot Area and test a few. Some are marked gnd put your black probe on that and probe the voltage wires with the red. Remember keep clear of the white hot section. Try and do 3v 5v 24v

[ddarn]

Re: Emerson hdtv troubleshooting

check the big cap again with power to the board again or unplug and check again?

[martino]

Re: Emerson hdtv troubleshooting

power on the board...if all is well,you should see around 160 volts DC on there....
If you DO measure that 160v DC,then do what selldoor suggested and look at those wire jumpers with voltage markings beside them...black probe on a wire jumper that says GND and red probe on the 5volt,3 volt etc...
I'd say the "all 5volt" wire jumper would be the most of interest for now,but check the 3volt etc too...

If you DON'T get the 160 volt DC on that main cap,we need to trace backwards,but then report back,as the voltage switches from DC back to AC at those 4 diodes...

[ddarn]

Re: Emerson hdtv troubleshooting

166.5 vdc..a certain area on the board to read the jumpers? they have over 50 easily and are reading different..

[ddarn]

Re: Emerson hdtv troubleshooting

I did 8 readings and I didnt see any jumpers for 5 volts..most of the ones I saw had 24v next to them.I also attempted to use a GND jumper that was near the jumper I was reading..readings are below:

J1061 (7.5V rating)--0 VDC
J1123(6V)--6 mV
J1125(3.3V)----0VDC
J1106 (.16V)---9.2 mv
J1081(24V)---9.31V
J1082(24v)---9.30V
J1059(12v)--.209V
J1101 (36V)--14.43V

[martino]

Re: Emerson hdtv troubleshooting

you won't see 24 volts etc untill we force on the power supply...

see pic,I marked the all 5 volt and GND and also ps-on...
Meter on DC scale,black on GND,red on all 5 volt jumper wire.... ?? volts?

Now,if you DO get 5 volt on the all 5volt jumper,then it's time to test if the mainboard tries to turn on the power supply...
Plug powerboard back in to mainboard and ALL other connectors...plug in the TV,put black probe on GND,red probe on the ps-on jumper wire,you will see 0 volts,KEEP probes on thse points and hit the power button on the tv(or remote)and see if now you read a voltage,could be anywhere from 1.8 to 5 volts...

[ddarn]

Re: Emerson hdtv troubleshooting

I got 4.43 Volts..

[martino]

Re: Emerson hdtv troubleshooting

On the all 5 volts or the ps-on?

[ddarn]

Re: Emerson hdtv troubleshooting

On the all 5 volts

[martino]

Re: Emerson hdtv troubleshooting

4.43 volts......seems a tad low,how fresh is the battery in your multimeter?

[selldoor]

Re: Emerson hdtv troubleshooting

Perhaps check the voltage on the cap C639 it is 10v so likely to be on 5v line.
It is just by the big transformer that goes from Hot to cold

[ddarn]

Re: Emerson hdtv troubleshooting

4.43 volts......seems a tad low,how fresh is the battery in your multimeter?

yes,I believe battery is good but I will use another meter and see if it comes up with the same thing.

[ddarn]

Re: Emerson hdtv troubleshooting

the other meter(fluke 7-300) reads 4.33 V.......c639-- 1 meter reads 2.678v(fluke 7-300) the other 3.55v(craftsman 82372)

[martino]

Re: Emerson hdtv troubleshooting

I don't like that 4.33 or 4.43 volt,selldoor you think that's too low too?
I assume you measured that with the main board disconnected,right?
Could we get a clear close up picture from the bottom side of the power board,showing the area where the all 5volt etc is?

[ddarn]

Re: Emerson hdtv troubleshooting

yes the main board was not connected..I will take a pic of the bottom side of the power board when i get off work tommorrow morning.

[ddarn]

Re: Emerson hdtv troubleshooting

the shopjimmy pic in post 14 will probably be clearer than mine..the shiny back on the board blurs my pics...I will upload a couple though and see if you can make anything out of them.I think the 3rd one is the least blurriest..good luck...

[selldoor]

Re: Emerson hdtv troubleshooting

May as well delete all except 3

Martino yes I think its too low but no idea why.

[martino]

Re: Emerson hdtv troubleshooting

I'm on the road so can't really see pic good. But I'm thinking of a Zener diode dragging down the 5 volt a bit. Wanted to see the traces to trace back the 5 volt line to transformer.