JVC LT-32DE74 won't turn on.

[Malachi]

Just picked this up today, it won't turn on, the front led stays red.
I measured the voltages on the power supply connector. I've got 12v where it is labeled 12v, 5v where labeled and PSON is 4.5v.
5VSBY is 5v.
There is a pin labeled DM that reads 4.7. BL-ON is 0V.

Measuring between the big cap shows 166V.

[budm]

Re: JVC LT-32DE74 won't turn on.

Well, you do not have BL-ON signal to turn the backlights circuits.
How about the pictures of the whole power supply to find out if it has PFC Voltage booster circuit or not?

[Malachi]

Re: JVC LT-32DE74 won't turn on.

Here you go.

[Malachi]

Re: JVC LT-32DE74 won't turn on.

Picture from shopjimmy might be clearer.

[Malachi]

Re: JVC LT-32DE74 won't turn on.

Any suggestio for what to check or should I throw boards at it?

[dick_barton]

Re: JVC LT-32DE74 won't turn on.

Can you jump a resistor from +5V to BL_ON to test if the backlights come on or flash briefly.

[Malachi]

Re: JVC LT-32DE74 won't turn on.

Can you jump a resistor from +5V to BL_ON to test if the backlights come on or flash briefly.

Tried it, nothing happened. I stuck it in with the connectors still in place. Is that ok?

Does this point to a power supply issue? There are only 2 listed on eBay.

[dick_barton]

Re: JVC LT-32DE74 won't turn on.

Have you looked to see what the voltage is at Con300 when you attempt to switch on. Looks like it only one led string.

[Malachi]

Re: JVC LT-32DE74 won't turn on.

Yes I checked yesterday. No voltage.
The tv has an actual on/off rocker switch in the back. When I flip it on, the front led turns red and that's it. Won't turn on at all, neither with the remote and the power button. No response at all.

Btw the tv is a tv/dvd combo unit.

[dick_barton]

Re: JVC LT-32DE74 won't turn on.

Tried it, nothing happened. I stuck it in with the connectors still in place. Is that ok?

Does this point to a power supply issue? There are only 2 listed on eBay.

No, you need to disconnect the mainboard. Use a 1K resistor to jump 5VSTY to P_On then check that all the supplies come up.
You can use a second jump resistor (1K) to then connect 5V to BL_ON.
Two resistors in total.

Edit.
I know that budm says that some board bring on the backlights when the psu is disconnected from the mainboard and then powered on because they already have pullup resistors.

[Malachi]

Re: JVC LT-32DE74 won't turn on.

I did that and the back lights came on. I didn't measure anything, I took the backlights turning on as a good sign?

[dick_barton]

Re: JVC LT-32DE74 won't turn on.

Looks like the mainboard is holding them off. Can you disconnect the dvd cable. I have a feint recollection that a previous post mentioned a problem with the dvd player which was faulty on their set and it powered up when the dvd was disconnected. Just a thought.

[Malachi]

Re: JVC LT-32DE74 won't turn on.

I had already tried that.
If you are confident it's the main board I can order one. I was afraid it might be the eeprom, as the description on shopjimmy sounded like it fit but there is no way I can replace it.

[dick_barton]

Re: JVC LT-32DE74 won't turn on.

Then it's looking more like a mainboard fault. Perhaps someone else can offer some advice.

[Malachi]

Re: JVC LT-32DE74 won't turn on.

Thanks for your help dick_barton.

I made an offer on the main board.

[dick_barton]

Re: JVC LT-32DE74 won't turn on.

Good luck. Hope it works out for you.

[Malachi]

Re: JVC LT-32DE74 won't turn on.

Got the eeprom. Lifted a pad while taking the old one off. Now I'm out $35 for a 32" tv.
That is why I don't like to attempt hose types of repairs.

Thanks for every one for trying to help.

[ReeceyBurger123]

Re: JVC LT-32DE74 won't turn on.

Try powering it up might have been a empty pad ?

[Malachi]

Re: JVC LT-32DE74 won't turn on.

I did. Nothing. Already put it all back together. There is a working board on eBay for $44 but it's not worth it. I'll wait to see if one cheaper shows up. If not I'll toss it.

[dick_barton]

Re: JVC LT-32DE74 won't turn on.

Got the eeprom. Lifted a pad while taking the old one off. Now I'm out $35 for a 32" tv.
That is why I don't like to attempt hose types of repairs.

Thanks for every one for trying to help.

You can solder a fine wire on the floating IC leg and bridge the break.