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Digihome 39" TV.

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sideband
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As this is a modern TV I thought it better to ask here rather than in the TV section. I've been asked to look at a Digihome TV model 39180SM with LED backlights. I presume it is a supermarket or catalogue model, about 3 - 4 years old. I can only assume it's made by Funai. Do Telra still manufacture sets?

Anyway the symptoms are no picture...nothing visible on screen at all no menus etc, sound OK. Quite plainly the backlights are not working. The standby light flashes a dozen or so times when first switched on then stops. Sound is present after this period. 

It's obviously showing an error code of some sort. I haven't even taken the back off yet so it may be nothing more than bulging caps in the power supply (he hopes)!! I don't really want to get too involved since the owner is not likely to want to pay for anything major (like a new LCD screen). 

Firstly is anyone familiar with this brand and secondly if it's not bulging caps in the power supply where should I start looking? Is it worth getting involved with?

Thanks for any pointers.

Rich.

 

 

 
Posted : 25/07/2019 9:26 pm
Nuvistor
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I think it’s worth asking how much they want to spend, can’t help with the fault apart from your own thoughts on bulging capacitors.

I have not done any repairs for for others for many years, when I was asked it was usually wanting something cheap.

 

Frank

 
Posted : 25/07/2019 9:50 pm
sideband
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As to how much they want to spend....not much! I did a quick Google and it seems to be quite a common problem.....but no answer as to what the fault is/was!

I assume there is an LED driver of some description but this will be controlled by something else. 

What I find strange is that modern TV's seem to fail in this way and yet I have a 15 year old Philips LCD with florescent backlights which is still going strong....never had the back off.

 
Posted : 25/07/2019 10:14 pm
Cathovisor
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Posted by: @sideband

Firstly is anyone familiar with this brand and secondly if it's not bulging caps in the power supply where should I start looking? Is it worth getting involved with?

I think it's worth finding a WEEE skip to lob it in. When I can buy a known brand of LCD set from my local auction house for less than £50 I find repairing things like this is just not worthwhile.

However, I found this: https://spares2repair.co.uk/digihome-39180sm-power-supply-23170550-17ips20-040313r5

 
Posted : 26/07/2019 4:13 am
sideband
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Well as it's a friend of my daughter I suppose it's worth taking the back off to see if I can find a duff cap but I've already warned her that it might not be fixable.

It's the usual scenario....low income family (she works for the NHS) and 3 kids to keep entertained...and of course school holidays have just started.....

Incidentally it looks like that power supply is sold out.....! Looking at the picture though it looks like it has the usual candidates for checking....those diodes for a start tend to fail s/c. I have a bag of large avalanche diodes since I had similar failings in a digibox a few years ago.

 
Posted : 26/07/2019 7:09 am
Cathovisor
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Sadly, that's always the way Rich: it happens to those that can least afford it at the most inconvenient time.

One thing that bothers me is that the panel itself may contain the backlight controller. 

 
Posted : 26/07/2019 8:09 am
crustytv
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Posted by: @sideband

it's a friend of my daughter I suppose it's worth taking the back off to see if I can find a duff cap but I've already warned her that it might not be fixable.

It's the usual scenario....low income family (she works for the NHS) and 3 kids to keep entertained...and of course school holidays have just started.....

This upsets me, our NHS workers are overworked and underpaid and the timing for the children, couldn't be worse. I know some might say well the kids can go out and play. Well yes they can but also when they've done that and its the evening or morning, the TV will be missed its part of modern life. Also If we were unwell its ladies like this who work all hours. in all departments. in all conditions, that would be helping towards our care without any hesitation.

I'm happy to pledge £50 towards a new TV, perhaps other Vratters might consider also helping those less fortunate by way of small donations. Perhaps if you get enough buy her the TV as a nice surprise or if we don't get enough at least she will have a good deposit towards one.

So come on Vratters, make your pledges here and lets see if we can get this sorted in a matter of days not weeks.  

Rich, let me have your Paypal details and I will send my donation to you to kick things off. (hopefully you're happy to handle all this). Nice 40" Toshiba or JVC from currys should do nicely.

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Posted : 26/07/2019 8:24 am
Cathovisor
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Okay, count me in too ? 

 
Posted : 26/07/2019 8:37 am
Red_to_Black, crustytv, Red_to_Black and 3 people reacted
Cathovisor
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Typical! Look what's just turned up at my local auction house:

Panasonic Viera 37" LCD television

Can't go and look at it though - the car's poorly (overheating, started doing it yesterday) ☹ 

Anyway, be easier if it's kept in Rich's locale.

 
Posted : 26/07/2019 9:54 am
Doz
 Doz
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I'll put a tenner in the hat.

 
Posted : 26/07/2019 10:45 am
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Nuvistor
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A tenner from me, I don’t have a PayPal account, presume I can still send it that way.

 

Frank

 
Posted : 26/07/2019 5:31 pm
Norman-Raeburn
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I would be more than happy to contribute, can we sort a link out for payment please. Norman

 
Posted : 26/07/2019 7:33 pm
sideband
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Hi Guys,

Thanks very much for your generosity. However I'm going to persevere a little longer. I found a very good 'over-the-shoulder' repair guide for this power supply (it's a Vestel 17IPS20 by the way) and I have already found a s/c chip capacitor in the LED driver stage. This was actually shorting the VCC line to chassis. Replacing this hasn't brought up the LEDs yet as I still have no VCC rail BUT I've just discovered a BC327 in the supply rail that is not measuring as it should (it appears to be O/C B-E). So tomorrow sometime I'm going to replace this transistor....it's too late now. So I may yet have some success. Will keep you posted.

I've also found a circuit for the PSU....it may not be completely accurate as it's an early version but it's near enough.

 
Posted : 26/07/2019 10:56 pm
Cathovisor
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@sideband

Good luck, Rich - BC327s are a good workhorse transistor and still common. My first (failed) attempt at making an amplifier for a transistor radio used one of those and its complement, the BC337. 

 
Posted : 27/07/2019 8:44 am
sideband
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*UPDATE* We have backlights!!!!! Fingers crossed! Now the BC327 I measured last night was indeed O/C B-E. The transistor was actually marked BC327-25....typically I only had standard BC327s. Checking specs there are several hfe groupings of -16, -25 and -40. The -25 group seem to have an hfe between 400 and 600 so I ran through all of mine and selected one with an hfe of 400, the highest I could find. Now fitted and the backlights work. The gain may not be important in a series regulator circuit but manufacturers don't normally fit higher gain transistors where standards will do.....and I have experienced intermittent start-up in the past where gains are critical.

Rather stupidly I left the remote control behind but there is a 'monoknob' on the side which operates standby, channel change and menu depending on whether you press up, down quick press centre or long press centre...

Next to connect an aerial and see if we can get pictures. I've already seen the 'No signal' up on screen so it's all looking good.

 
Posted : 27/07/2019 12:57 pm
Red_to_Black, Nuvistor, crustytv and 6 people reacted
Cathovisor
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Nice one, Rich: saved from the WEEE skip to live again! 

 
Posted : 27/07/2019 2:08 pm
sideband
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Well we have success! The TV has been running for around four hours....it'll need a long soak since during the school holidays it's likely to get quite a bashing from her kids what with Playstations and DVD's.

Total component count 2....one chip 10nF cap and one BC327 (specially selected for gain). The cost of those two items I'd optimistically put at £1....they didn't actually cost me anything.

Just out of interest while I had the power supply on the bench, I ran through the electrolytics and found them all to be in very good order.

Maybe I was lucky with this one since Googling around it seems these are prone to quite major failures. No guarantees of course but hopefully it will buy the owner a little more time before a new TV is required.

Not a particularly good screenshot since it was taken on the phone camera

 

IMG 20190727 154634

 

 

 
Posted : 27/07/2019 6:45 pm
Red_to_Black, Nuvistor, Red_to_Black and 3 people reacted
crustytv
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Once a TV engineer, always a TV engineer no matter the technology in between , great result Rich. Really pleased you sorted it and no doubt your daughters friend and her kids will be too.  ? 

CrustyTV Television Shop: Take a virtual tour
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Posted : 27/07/2019 6:49 pm
sideband
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Now enjoying a DVD of the original and best 'The Italian Job' from 1969.

 
Posted : 27/07/2019 7:06 pm
Cathovisor
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'sfunny, at work people still can't get their head around me owning and using daily a 28 year old (I think, I'm struggling to remember now!) 24", 4:3 CRT Panasonic...

 
Posted : 27/07/2019 7:58 pm
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