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Old 26th Nov 2023, 8:44 pm   #1
SpyguyUK
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Question Hitachi TV - 32LD6600 - Power On Takes A Few Attempts - Powers Off OK - Why Is This?

Hi,

We have a Hitachi LCD TV - 32LD6600 that I have had for 17 years and it is on every day.
For the last few months or so I have to press the Remote Control a few times to Turn TV on from Stand By which it's always on.

However when Powering Off it goes off on first attempt.

Maybe the TV just has to heat up to get certain possibly capacitor/s to function properly? Could this just be a capacitor needing replaced or a problem with the motherboard?

Do any of you know what the problem might be?

Thanks.
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Old 26th Nov 2023, 8:50 pm   #2
G6Tanuki
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Default Re: Hitachi TV - 32LD6600 - Power On Takes A Few Attempts - Powers Off OK - Why Is Th

In many switched-mode power supplies there is a little 'phantom' power-supply driven via a resistor from the rectified mains supply; this provides a few microamps to power the remote-control-receiver so it is always looking for the power-on button to be pressed, and when it sees it, it sends a signal to the main SMPS to swing into action.

If this little phantom power-supply's feed resistor has gone high-resistance [remember it's powered up all the time...] it might not allow enough of a current-pulse to be sent to the main SMPS to kick it into action when the remote's power-on-button is pressed.

The startup-resistor [sometimes two resistors in series to give a higher voltage rating for safety] is often a very high value - 100K to 470K Ohms.

And they are prone to drifting higher with age.
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Old 26th Nov 2023, 8:52 pm   #3
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Default Re: Hitachi TV - 32LD6600 - Power On Takes A Few Attempts - Powers Off OK - Why Is Th

Also, dried out capacitors; look for the top bulging.
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Old 26th Nov 2023, 9:27 pm   #4
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Default Re: Hitachi TV - 32LD6600 - Power On Takes A Few Attempts - Powers Off OK - Why Is Th

Couple of years ago I had an Hitachi TV in for repair and although it said Hitachi Europe on the back it was actually mostly Vestel inside. The screen and driver board was made by LG. All the faults were on the Vestel power board. Almost every electrolytic capacitor was faulty in some way. Mostly low capacity and all were replaced and the problem went away. The user normally left the set on 24/7 because of the difficulty getting it to switch on and killed the picture by turning off the Sky box.
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Old 27th Nov 2023, 11:51 am   #5
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Default Re: Hitachi TV - 32LD6600 - Power On Takes A Few Attempts - Powers Off OK - Why Is Th

This uses the Vestel 17PW15/9 power supply.

You'll need to replace two 4700/6.3v capcitors (lower centre) and three 1000uF, 16v caps, one above the long heatsink and the others on the left. There's also a 100uF stuck
in the top centre that can bulge as well - a bit fiddly, that one.

Then check the two 15nF polystyrene capacitors at the extreme top left - if they're light blue and boxy change them.
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Old 27th Nov 2023, 8:14 pm   #6
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Default Re: Hitachi TV - 32LD6600 - Power On Takes A Few Attempts - Powers Off OK - Why Is Th

Quote:
Originally Posted by G6Tanuki View Post
In many switched-mode power supplies there is a little 'phantom' power-supply driven via a resistor from the rectified mains supply; this provides a few microamps to power the remote-control-receiver so it is always looking for the power-on button to be pressed, and when it sees it, it sends a signal to the main SMPS to swing into action.

If this little phantom power-supply's feed resistor has gone high-resistance [remember it's powered up all the time...] it might not allow enough of a current-pulse to be sent to the main SMPS to kick it into action when the remote's power-on-button is pressed.

The startup-resistor [sometimes two resistors in series to give a higher voltage rating for safety] is often a very high value - 100K to 470K Ohms.

And they are prone to drifting higher with age.
Hi,

Thanks for that. Can you direct me to where this resistor would be? I've uploaded photos of TV and PCB's in new post.
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Old 27th Nov 2023, 8:18 pm   #7
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Default Re: Hitachi TV - 32LD6600 - Power On Takes A Few Attempts - Powers Off OK - Why Is Th

Quote:
Originally Posted by Welsh Anorak View Post
This uses the Vestel 17PW15/9 power supply.

You'll need to replace two 4700/6.3v capcitors (lower centre) and three 1000uF, 16v caps, one above the long heatsink and the others on the left. There's also a 100uF stuck
in the top centre that can bulge as well - a bit fiddly, that one.

Then check the two 15nF polystyrene capacitors at the extreme top left - if they're light blue and boxy change them.
Hi,

Thanks for this information. This is the same TV that I repaired in November last year. I replaced a few caps on PCB and it corrected fault, the picture took ages to come on.
Can you see the caps you mentioned on the photos I'm about to upload?
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Old 27th Nov 2023, 8:40 pm   #8
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Default Re: Hitachi TV - 32LD6600 - Power On Takes A Few Attempts - Powers Off OK - Why Is Th

Hi,

Thanks to all of you for your helpful advice. As I said this TV I repaired last November funny enough.
Here is a photo of TV and PCB and all boards. If you can see the caps/resistor that may be at fault maybe you could tell me where they are in relation to the caps circled. I replaced all the caps circled red and blue, I think I replaced the cap circled green also.
Attached Thumbnails
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Name:	Hitachi - 17PW15-8 (4).jpg
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Name:	Hitachi TV - 2.jpg
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Old 28th Nov 2023, 1:48 am   #9
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Default Re: Hitachi TV - 32LD6600 - Power On Takes A Few Attempts - Powers Off OK - Why Is Th

I assume these pictures are "before"?
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Old 28th Nov 2023, 5:32 am   #10
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Default Re: Hitachi TV - 32LD6600 - Power On Takes A Few Attempts - Powers Off OK - Why Is Th

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I assume these pictures are "before"?
Yes, these caps circled I replaced for the last fault it had.
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Old 28th Nov 2023, 11:58 am   #11
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Default Re: Hitachi TV - 32LD6600 - Power On Takes A Few Attempts - Powers Off OK - Why Is Th

Although they don't look in distress, I would replace the two 4700uF capacitors towards the middle at the bottom of the panel. The two 15nF capacitors are fine.

We have had odd faults with the start-up resistors as mentioned, but usually it's due to poor soldering. They are SMD components in a 'ladder' so are easy to spot. Reflowing them often cures intermittent start-up from cold. There are also a couple of small SMD transistors that often didn't get soldered properly from new - a small iron and a good magnifier are essential here.
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Old 28th Nov 2023, 12:27 pm   #12
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Default Re: Hitachi TV - 32LD6600 - Power On Takes A Few Attempts - Powers Off OK - Why Is Th

Still not sure which have been replaced. The blue circle has an obviously bulging cap that needs replacing. Unless the picture is before you replaced it last November. By the time they are bulging they are well past their useful life. The only real way to tell is with a capacitance meter otherwise it's guesswork. Several of the others could be faulty even though they are not yet bulging.
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Old 28th Nov 2023, 8:51 pm   #13
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Default Re: Hitachi TV - 32LD6600 - Power On Takes A Few Attempts - Powers Off OK - Why Is Th

All the circled caps were replaced. The photo is before replacement. I think I did the green circle as well. All the blue circled caps have been replaced for sure. Any ideas?

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Old 28th Nov 2023, 8:53 pm   #14
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Default Re: Hitachi TV - 32LD6600 - Power On Takes A Few Attempts - Powers Off OK - Why Is Th

Quote:
Originally Posted by Welsh Anorak View Post
Although they don't look in distress, I would replace the two 4700uF capacitors towards the middle at the bottom of the panel. The two 15nF capacitors are fine.

We have had odd faults with the start-up resistors as mentioned, but usually it's due to poor soldering. They are SMD components in a 'ladder' so are easy to spot. Reflowing them often cures intermittent start-up from cold. There are also a couple of small SMD transistors that often didn't get soldered properly from new - a small iron and a good magnifier are essential here.
OK, thanks. Is it the power supply board that should be focussed on only?
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Old 29th Nov 2023, 1:25 pm   #15
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Default Re: Hitachi TV - 32LD6600 - Power On Takes A Few Attempts - Powers Off OK - Why Is Th

I'd say so, though at this age a main board fault could be responsible but unlikely.
Maybe a little heat and freezer might help?

PS Tucked in the top left coner in the bend of the heatsink are two electrolytics that don't take too kndly to their location. Perhaps replace these as well.
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Old 30th Nov 2023, 5:10 am   #16
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Default Re: Hitachi TV - 32LD6600 - Power On Takes A Few Attempts - Powers Off OK - Why Is Th

Quote:
Originally Posted by Welsh Anorak View Post
I'd say so, though at this age a main board fault could be responsible but unlikely.
Maybe a little heat and freezer might help?

PS Tucked in the top left coner in the bend of the heatsink are two electrolytics that don't take too kndly to their location. Perhaps replace these as well.
Hi Glyn,

Thanks. I will concentrate on the PSB as this as in many cases is where the problem was last time.
The TV is in a fairly warm room. I notice that when the TV has been on during the day it comes on as it should and goes off first time also. I did this quite a few times. But after being left on standby again for a few hours the issue was back.

What did you mean?
"Maybe a little heat and freezer might help?"


I'll try and find those caps you have previously mentioned but I don't suppose there is any way you could circle them from the photos I posted above and reupload the photos? Don't worry if you can't. I may do some of the others anyway if I have the caps. It's just I would prefer to do the caps mentioned and not all. Thanks again for your help.
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Old 30th Nov 2023, 12:21 pm   #17
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Default Re: Hitachi TV - 32LD6600 - Power On Takes A Few Attempts - Powers Off OK - Why Is Th

you may notice that there are plenty of used boards for sale from £4.95 plus carriage and dont appear to have swollen caps [although some from a good seller at £29.95 ] do have .might be a quicker resolution if you feel you need it. we used to carry spare boards back in the day for these on the allianz / argos contract and then repair and soak the m in the workshop .from memory they were replaced by the 17pw15/20 which came with some adaptor leads .so that might be another quick solution .
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Old 30th Nov 2023, 9:26 pm   #18
Maarten
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Default Re: Hitachi TV - 32LD6600 - Power On Takes A Few Attempts - Powers Off OK - Why Is Th

Vestel power supplies may have been customised for screen size, mainboard version, etc. So in some cases it might be easier to repair the one you already have than to find one that's an exact match, though I don't know for sure if this also applies to somewhat older generations such as this one.

Another reason to repair instead of replace with a used one, is that you have a better chance of it lasting for a while again after the necessary repairs.
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Old 1st Dec 2023, 1:30 am   #19
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Default Re: Hitachi TV - 32LD6600 - Power On Takes A Few Attempts - Powers Off OK - Why Is Th

Quote:
Originally Posted by gallowfields View Post
you may notice that there are plenty of used boards for sale from £4.95 plus carriage and dont appear to have swollen caps [although some from a good seller at £29.95 ] do have .might be a quicker resolution if you feel you need it. we used to carry spare boards back in the day for these on the allianz / argos contract and then repair and soak the m in the workshop .from memory they were replaced by the 17pw15/20 which came with some adaptor leads .so that might be another quick solution .
I was thinking this too which would save time and effort and last year I bought one just to confirm it was PSB at fault and it was but when using this board picture on TV was dull. I was looking at this board from last year and I now notice that one of the pins on the white socket is missing. I don't remember if it came that way or if I broke it. I replaced bulging caps on my own just for fun but in this case I don't know which cap/s are at fault.
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Old 1st Dec 2023, 1:37 am   #20
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Default Re: Hitachi TV - 32LD6600 - Power On Takes A Few Attempts - Powers Off OK - Why Is Th

Quote:
Originally Posted by Maarten View Post
Vestel power supplies may have been customised for screen size, mainboard version, etc. So in some cases it might be easier to repair the one you already have than to find one that's an exact match, though I don't know for sure if this also applies to somewhat older generations such as this one.

Another reason to repair instead of replace with a used one, is that you have a better chance of it lasting for a while again after the necessary repairs.
I know like I was saying to gallowfields I bought a second hand board just to confirm it was PSB at fault last year and it was but when using new board picture on TV was dull. I was looking at this board from last year and I now notice that one of the pins on the white socket is missing. I don't remember if it came that way or if I broke it.

Anyway someone said that even though it's exact same board for that TV - Hitachi TV - 32LD6600B it made have been manufactured at another factory or on another run/production line that may be reason for dull picture so I just replaced caps. I didn't mind doing this but I'm now thinking maybe the missing pin was causing dull picture on TV!
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