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  #1  
Old 11-28-2012, 07:28 PM
dnpainting dnpainting is offline
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Sanyo DP42848 Help!

Looking for help with this unit. It is my neighbors TV and not much info except that the tv went out during a storm. I've downloaded the SM and opened it up. No bulging or leaky caps from what I see. I Plugged it in and turned it on. On the PS board, there is a blue relay at the bottom that just clicks. Nothing else happens. In the service manual, it says that this board has no useable parts and so nothing is listed and no schematic either. It seems that all the transistors are soldered from both top and bottom on one leg of each.

Should I have the owner just buy a new PS board, if I can find one? Or could it be something else in this thing?

Thank you
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  #2  
Old 11-28-2012, 08:06 PM
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crtfool crtfool is offline
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I would hope that the board does have useable parts!! I think that you meant to say that it has no user serviceable parts.

You really need to have an ESR Meter to reliably test Electrolytic Capacitors.

Can you post clear pictures of that board, and closeups of all the connectors and their markings? It looks like the power supply outputs 5v, 12v ,and 24v to the main board via CN2 - can you measure those voltages to see if they are correct?
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  #3  
Old 11-28-2012, 08:50 PM
dnpainting dnpainting is offline
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Did the measurements. I have +5vdc but no 12vdc and no 24vdc on CN2. When the relay clicks, the green power light goes on.

Thank you for your help with this. Here is a pic of the board



I will go get close-ups of the connectors and post them
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  #4  
Old 11-28-2012, 08:56 PM
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Do you have 12v and 24v when the green power light is lit? You may only have a few seconds to get the reading before the TV shuts down. The 5v is the standby voltage that should be present when the TV is off.
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Old 11-28-2012, 09:11 PM
dnpainting dnpainting is offline
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Close-Ups









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  #6  
Old 11-28-2012, 09:18 PM
dnpainting dnpainting is offline
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Quote:
Originally Posted by crtfool View Post
Do you have 12v and 24v when the green power light is lit? You may only have a few seconds to get the reading before the TV shuts down. The 5v is the standby voltage that should be present when the TV is off.
Yes, the 12 and 24vdc are present at CN2 and 24vdc is also at the 2 inverter connectors

Last edited by dnpainting; 11-28-2012 at 09:23 PM.
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Old 11-28-2012, 09:23 PM
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OK - then that means that the Power Supply is good. Do the Backlights light up when the TV powers on? If not, then disconnect connector K8L from the Main Board and try again to see if the Backlights light up.
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Old 11-28-2012, 09:28 PM
dnpainting dnpainting is offline
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Yes, only with K8L disconnected
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Old 11-28-2012, 09:32 PM
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crtfool crtfool is offline
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OK - then that means that the Inverters are most likely not faulty either. It looks like the Main Board is faulty.

If the Inverters were faulty, the TV would most likely stay on, but without the Backlights being lit.

Last edited by crtfool; 11-28-2012 at 09:35 PM.
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  #10  
Old 11-28-2012, 09:37 PM
dnpainting dnpainting is offline
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And it is full of SM components. I will test what I can but I doubt if I'd be able to find a bad component.

I thank you so much for the time and help
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  #11  
Old 11-28-2012, 09:43 PM
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Yeah - Main Boards are very hard to troubleshoot. If you can't find an obviously bad component, then it would be best to just replace the board - they seem to be available on eBay for between $55 and $85.
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  #12  
Old 11-28-2012, 09:45 PM
dnpainting dnpainting is offline
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thank you again for all your help
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  #13  
Old 12-18-2012, 09:24 AM
dnpainting dnpainting is offline
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Well, the owner of the TV did not want to buy another main board for it. He said it wasn't worth te $60.00 for the board along with the $50 for my time. So, he just gave me the tv for my troubles.

I purchased a used main board off ebay that was guaranteed to be working, installed it and that was it. TV is now fully functioning.

I did want to ask if it would be a good idea to put in new thermal compound on the CPU?

Thank you crtfool for all your help!
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  #14  
Old 12-18-2012, 06:25 PM
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Your welcome, and glad that you fixed it for a reasonable price. If it is easy to do without getting the compound all over the other circuitry, then it could not hurt.
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