TV repair help, blown caps

[Griffinballs]

Hi all.
Got a Hitachi 42" lcd tv. It's had an issue where it's been taking ages to turn on.
I took it apart, found five blown caps on the power supply. Replaced them, now it works fine, but now I can't put the TV into standby, it switches off but the power led continuously flashes red and never goes solid red.
I used two caps of slightly different value, higher on voltage which I was led to believe was OK to do.
The values that I substituted were. 470uF 36v, I used 470uF 50v and a 1000uF 50v, I used 1000uF 63v.
Any idea on my problem?
Many thanks

 

[davenn]

The values that I substituted were. 470uF 36v, I used 470uF 50v and a 1000uF 50v, I used 1000uF 63v.

welcome to EP

there's no problem using caps of a higher voltage rating ... in fact, it's preferable
The only time that is a problem is when the higher voltage one is physically larger and wont fit when the lower voltage one went ( closeness of other components etc)

the standby prob ... difficult to say
have you tried to get any service info for the TV ?, a service manual would be great, circuit diagrams would be helpful

Dave

 

[Martaine2005]

If the standby worked before you opened the TV, I would double check all the connectors.
You wouldn't be the first or the last to forget a connector or even plug it in wrong..

Martin

 

[Griffinballs]

Hi Martin, thank you. But yes unfortunately, I've plugged all connectors in fine, there weren't very many so it was pretty easy to not miss any

 

[Martaine2005]

Hi, just found this in the manual for a Hitachi 42 inch lcd.
May or may not be anything but...

NOTE: When the TV is switched to standby
mode, standby LED can blink to indicate that
features such as Standby Search, Over Air
Download or Timer is active.

Certainly worth checking your MENU and setup items.

Martin

 

[Griffinballs]

Thanks Martin, I'll have a look in the menus when I get back home

 

[Griffinballs]

OK. Back home now. Been through my TV's menu extensively, I have no options for things left on. Its not a smart TV, its a regular kind. Model is Hitachi 42FPDEUDA1
I've tried the software upgrade on it which doesn't show any updates, last updated 2009.

I decided to just leave it on standby and see if it eventually stopped but it still hasn't. Just flashing between red and no led roughly two seconds on each before repeating endlessly.

It doesn't seem to be causing any problem, tv is working as normal, but I'm sure as hell it shouldn't be doing it.

Before I "fixed" it, it would do this every now and then but usually a few seconds later would stop. It also used to come on randomly, like midway through the night and stuff for no apparent reason. I'd hoped that me replacing the caps would fix all the gremlins it had, not emphasise one of them more than before.

I did use one used capacitor which came from an old motherboard, its value was identical to the one I was replacing but it was a lot bigger. The board was over ten years old too, but the cap looked good. Its value was 2700uF 16V. It was a lot taller than the one I replaced but the temp and everything were the same. Thats the only thing I can think of that I did that wasn't normal

 

[Martaine2005]

Hi,
Thanks for the update.
FYI, the cap doesn't have to look bad to BE bad.
I would change that 10 year old cap for a new one before doing anything else.
They do dry out, not always bulge or leak.

Martin

 

[Griffinballs]

Thanks Martin.
It was only as Maplins didn't have a suitable one in stock. I'll grab a new one for that before fault finding any further.
And thanks for responding so fast

 

[Martaine2005]

No problem,
Keep us all informed on your progress.

Martin

 

[Griffinballs]

Well. Alls well that ends well I guess. Still downright irritating.
Not more than 3 minutes after I placed the order and paid on eBay for the new cap, the TV just started switching off normally. It seems to have stopped whatever the hell it was doing lol. So for now I'm not gonna replace the dodgy cap, but I'll keep it in mind if it goes again.

Thanks for all your help guys. I'm definitely gonna stick around, looks like I can learn a lot here.
I fix pcs for a living so I'm sure I may be able to help with computer queries. Cheers for the warm welcome guys

 

[Martaine2005]

Hi,
I think it will be beneficial to replace the cap.

Or you might start getting symptoms again. As you don't know what that cap is doing on the circuit.
If they are all new, you can count them out.
The old cap might have needed several hours to revive. So it is defective.

Martin

 

[Griffinballs]

Point taken. I'll swap it out when it arrives, only takes a couple of mins anyway so it should give peace of mind. Thanks again

 

[Martaine2005]

Keep us all posted

Martin