akai lct3285ta power on issue

[craigc15]

I've been troubleshooting this TV for too long and I could use some help.
I replaced all bulging caps on the PS, but I have this weird situation that I thought I had overcome, but now it's back.
The standby light comes on, but when you hit the power button, the red standby LED blinks but that's it. I don't have the schematic, but I happened across a remedy, that had now failed, too. I was able to get the set to power up by putting a 50 ohm resistor across the 5VSB supply and that worked for a week, or so, but now it's back to the original problem.
I wasn't crazy about the kludge, but it worked, until now.
Any thoughts on what might be happening here?

Thank you!
Craig

[tom66]

Re: akai lct3285ta power on issue

What capacitors did you use as replacements?

[craigc15]

Re: akai lct3285ta power on issue

I didn't replace all of them, the guy that gave the TV to me must have replaced them.
I just replaced the 3 - 1000uf in the 5VSB supply with 3- 1800uF and it turns on fine now, even without the resistor!
Now I just have to figure out why the buttons/remote don't work consistently, and why it stays stuck in "DTV Initial". I can't select "DTV" in the menu to set up the digital tuner.
Any idea what might be causing these problems?

Thank you VERY much Tom. You seem to be the only person out there offering help, so it's much appreciated.

Craig

[craigc15]

Re: akai lct3285ta power on issue

Well, it was nice while it lasted, but now it's back to not coming on.
The 5VSB goes wild when I press the power button. I was able to get it to come back on by putting a 2o ohm load across the 5VSB. I even turned it off and back on without the load.

I am using Panasonic low esr caps.

HELP!

[tom66]

Re: akai lct3285ta power on issue

What series of capacitor did you use? Ultra low ESR can cause problems too -- the cap needs to be low ESR but not too low (i.e. motherboard grade.) 2 ohm is also much too high of a load on 5Vsb.

[ben7]

Re: akai lct3285ta power on issue

The little capacitors 10uf to 47uf commonly go bad too.

[budm]

Re: akai lct3285ta power on issue

"I just replaced the 3 - 1000uf in the 5VSB supply with 3- 1800uF" Are they all connected in parallel? That is a lot of capacitance from 3000uf to 5400uF.

[craigc15]

Re: akai lct3285ta power on issue

Essentially, they are in parallel. They're part of a pi filter: 2 before an inductor and 1 after. I just thought I'd experiment. I'll put the 1000's back in.
This set is a lower priority. I'm dealing with some others right now and then I'll go back to this one.
I'll post an update when I have more info.

Thanks!

Craig

[craigc15]

Re: akai lct3285ta power on issue

Thanks Ben!
One of the 10uf caps in the 5 volt PS section was bad. Turns on great now.

All that I need to do now is figure out why the buttons and remote don't work for the first 5-10 minutes.

[panzerpat]

Re: akai lct3285ta power on issue

Hello,

I'm working on the same kind of tv, I already replaced all the power board capacitors 3 days ago and it worked fine (although it took a good 4 mins. to start)
Now today all of a sudden the red light is blinking again and it won;t turn on for anything..
Anybody got any ideas?

I used this kit to repair the powerboard;

http://www.ebay.com/itm/230840928125...84.m1497.l2649

[lzep]

Re: akai lct3285ta power on issue

Hey there craigc15, did you ever discover the solution to your issue regarding the remote not working for several minutes after turn on. I am having the same problem.