Emerson hdtv troubleshooting

[ddarn]

Re: Emerson hdtv troubleshooting

look at post 14..budm gets clear pics from shopjimmy

[martino]

Re: Emerson hdtv troubleshooting

I tried tracing back the all 5volt with pic from post #14,but having a hard time,any one have better eyes then me?

[ddarn]

Re: Emerson hdtv troubleshooting

any better pics that can be found?

[budm]

Re: Emerson hdtv troubleshooting

Try this service manual, per shopjimmy, this model uses the same power supply.

[martino]

Re: Emerson hdtv troubleshooting

Budm,what would we do without you?

[budm]

Re: Emerson hdtv troubleshooting

Diagram for the power supply board. It looks real close to the OP board.

[ddarn]

Re: Emerson hdtv troubleshooting

so what gets tested next?

[martino]

Re: Emerson hdtv troubleshooting

Sry,been busy doing yard work etc. was hoping someone would jump in. Lol. I downloaded the schematics. Will check in a few hours.

[martino]

Re: Emerson hdtv troubleshooting

See pic....
Red probe on the leg of D637,black on chassis of tv,meter on 200volt scale DC...
What voltage do you read there...

[ddarn]

Re: Emerson hdtv troubleshooting

I apologize..my electricity was out here again because of wind..anyway concerning the last check the card isnt connected to the tv, so what else can I use to put the black probe on besides the chassis of the tv?

[selldoor]

Re: Emerson hdtv troubleshooting

You can use one of the wire jumpers that is marked GND Has to be on the COLD side
example J1086 in the picture straight down from the big red 2.

[ddarn]

Re: Emerson hdtv troubleshooting

8.83v

[martino]

Re: Emerson hdtv troubleshooting

8.83v

That should be approx 24volts....

Give me a minute,I need to see if that's with powerboard forced on or in standby..It giving 8.83volt already should almost indicate that it's somewhat active but not correctly...

[martino]

Re: Emerson hdtv troubleshooting

***just to be sure,you measured on the leg of D637 that's in the circle,correct?****

Let's assume you did,now right next to D637 you see a smaller diode D648,can you desolder one of it's legs(doesn't matter which one)so it's out of the board and then re-measure the same leg off D637? Still 8.83volt?

D648 is parallel between GND and the 24 volt line,I'm thinking that if D648 is leaking(halve shorted) it could pull down the 24 to 8.83 and also affect the all 5volt line a bit(4.43volt) as they both come out of the same transformer.D648 being a zener diode,when the voltage spike happened,it might have seen a over voltage and could have sustained damage as it was trying to dim the spike...just a thought....

[ddarn]

Re: Emerson hdtv troubleshooting

yeah I will desolder it when I get off of work tonight and give you the results tommorrow.

[ddarn]

Re: Emerson hdtv troubleshooting

it came out to be 9.21 volts

[martino]

Re: Emerson hdtv troubleshooting

hmm...I'm wondering if T600 get's driven correctly...24v=8.83,5v=4.43 etc....
With meter on 200volt DC(just to be safe) can you measure across the legs of diode D604?red probe on one leg,black probe on the other
It's right below the 2 white resistors on the HOT side(careful).
It should read 3.7 volt DC. I say,use 200 volt scale just to be safe,if you do see 3. something,you could turn scale to 20 volt.

[martino]

Re: Emerson hdtv troubleshooting

I would like to get budm in here now too,lol.... It's a fairly simple power supply,but the lower voltages it's given us is confusing me a bit,it's functioning but not on full 100%.
Budm,I'm thinking Q600/Q601 circuit being drawn down?

[ddarn]

Re: Emerson hdtv troubleshooting

hmm...I'm wondering if T600 get's driven correctly...24v=8.83,5v=4.43 etc....
With meter on 200volt DC(just to be safe) can you measure across the legs of diode D604?red probe on one leg,black probe on the other
It's right below the 2 white resistors on the HOT side(careful).
It should read 3.7 volt DC. I say,use 200 volt scale just to be safe,if you do see 3. something,you could turn scale to 20 volt.

2.43 volts

[ddarn]

Re: Emerson hdtv troubleshooting

2.43 volts

and the other diode still has the one leg removed from the board.