View Full Version : Apex LD4688 No power or standby


drjameshouse
04-10-2015, 08:12 PM
Hello,

A friend dropped off an apex ld4688 tv and said when they moved he hooked something up backwards (not sure what or how) and now the tv won't power on. If you plug it in there isn't a standby light. If you use the remote to turn power on or the button, no picture, no power light.

I did find this thread: http://www.videokarma.org/showthread.php?t=261370&highlight=apex+ld4688

I tried to follow it as best I could. I don't see any bubbled caps, and the fuse is still good on the PSU.

If I test the stanby pin going out of the PSU to the main it is 4.92V. If I jump the standby 5v pin, the 12V pins on the PSU all read 11.44V. Are these adequate readings?

With the pins jumped I tested the regulator U10 on the board and had 4.88V in and 2V out.

I should note that my friend couldn't find the power supply cord so I have tried various Computer PSU cords that are 10A 120V, and have had same results on everything.

I am happy to buy a new PSU, Main board, both, or just junk the tv and buy a new, but if I can get this one working for the least amount I would really be happy as a clam!

Thanks for any help. Here are links and numbers of the boards in the tv:
PSU: MLT198TX http://www.shopjimmy.com/megmeet-mlt198tx-power-supply.htm
Main: 1008H1666 http://tcoutlet.com/epages/b1a2da86-4c18-416b-8c46-51596e231151.sf/en_US/?ObjectPath=/Shops/b1a2da86-4c18-416b-8c46-51596e231151/Products/86

Service Manual: http://elektrotanya.com/apex_ld4688_lcd_tv.pdf/download.html

Username1
04-12-2015, 10:02 AM
-WOW- Good to have you here, It's great that you added several
links to the manual to help people here assist you with this tv....
It's not a good idea to jump across differing power supply sources
as it sounds that you have done, that can burn out parts in the tv....

Give people here who are more familiar with the insides of these newer
flat panel tv's a chance to look over the schematic, and ask you questions
that you can answer, and hopefully you can get it working...

Good Luck....

.

drjameshouse
04-12-2015, 02:35 PM
It's not a good idea to jump across differing power supply sources
as it sounds that you have done, that can burn out parts in the tv....
.

It's not really power supply sources (if I understand that correctly), just the cord for the power supply. It looks like this:

http://ecx.images-amazon.com/images/I/41P%2BwDiiVDL.jpg

I assumed since it was rated the same it would be fine. If not I'll have to see if I can find a replacement, but I wasn't able to find one in my quick 5 minute google search specifically for this apex tv.

Thanks for the reply. I am hoping I can get some advice this week, otherwise I'll just start buying parts. I would really like to learn about diagnosing electronics like this so I am glad to find a forum with so much information.

Electronic M
04-12-2015, 03:31 PM
That cord is a standard computer power cord. You can find one at most thrift stores, and computer places that deal with older equipment.