Sanyo DP46841-00 No power, no lights, no picture

[kage]

Hello all,

I am working on this tv for a family member who has had it in once for service due to lightning surge. The owner believes this has happened again as it will not do anything (no picture, sound, lights, anything). I have opened the case and after checking caps and making sure there were no obvious signs of damage (burn marks, etc) I took some voltage measurements.

On the Power Supply connector to the analog? board I got these readings:

24V = Fluctuating between 9.5 and 10.5V
12V = fluctuating between 2.5 and 3.5V
5V = 5.08V
PSon = .2-.3V
Lineoff = 3.25V

I have a multimeter and I do know how to use it. I have a decent knowledge of electronics and electricity but limited understanding of diagnostics.

I can take any pictures needed. If I can determine what board is bad I can make a recommendation to the owner as to what needs to be replaced.

Thank you!

[zacheriaj]

Re: Sanyo DP46841-00 No power, no lights, no picture

Pictures will help. Lets see if we can figure out what the previous repair was to see if it simply failed for whatever reason. Your standby supply is working. Disconnect the inverter board and check voltage again.

[kage]

Re: Sanyo DP46841-00 No power, no lights, no picture

Inverter board is the one that supplies power to the lamp correct?

It appears that the previous repair was done to the inverter as the connector is covered in what appears to be medical tape. I have not removed the cover on it yet. With it disconnected I get the same readings.

Also did I attach the images correctly? I don't want to make this difficult.

[zacheriaj]

Re: Sanyo DP46841-00 No power, no lights, no picture

pictures came in fine. disconnect the inverter board from the power supply, plug it in and measure the voltages on the connector to the main board before and after pushing the power button. not sure what the connector number is from the pictures. The reply should look something like this.

5Vstb: 5v
12V: xx.xx
24v: xx.xx
etc.

Make sure to put the board with the buttons back in before doing so. no need to have it out.

[kage]

Re: Sanyo DP46841-00 No power, no lights, no picture

pictures came in fine. disconnect the inverter board from the power supply, plug it in and measure the voltages on the connector to the main board before and after pushing the power button. not sure what the connector number is from the pictures. The reply should look something like this.

5Vstb: 5v
12V: xx.xx
24v: xx.xx
etc.

Make sure to put the board with the buttons back in before doing so. no need to have it out.

Just so we are clear.... The inverter board is the one with the black plastic cover right?

[zacheriaj]

Re: Sanyo DP46841-00 No power, no lights, no picture

Just so we are clear.... The inverter board is the one with the black plastic cover right?

correct

[kage]

Re: Sanyo DP46841-00 No power, no lights, no picture

pictures came in fine. disconnect the inverter board from the power supply, plug it in and measure the voltages on the connector to the main board before and after pushing the power button. not sure what the connector number is from the pictures. The reply should look something like this.

5Vstb: 5v
12V: xx.xx
24v: xx.xx
etc.

Make sure to put the board with the buttons back in before doing so. no need to have it out.

Voltages are the same as originally stated regardless of pressing the power.

[zacheriaj]

Re: Sanyo DP46841-00 No power, no lights, no picture

You're not getting a PWR_ON signal from the main board which may likely be the problem. Not quite sure why you are receiving voltages on the 12 and 24v line though. Place your red probe on PS_ON and black on chassis (Ground screw is fine). see if the voltage changes as you push the power button

[kage]

Re: Sanyo DP46841-00 No power, no lights, no picture

You're not getting a PWR_ON signal from the main board which may likely be the problem. Not quite sure why you are receiving voltages on the 12 and 24v line though. Place your red probe on PS_ON and black on chassis (Ground screw is fine). see if the voltage changes as you push the power button

Between .19 and .25V regardless of button.

[zacheriaj]

Re: Sanyo DP46841-00 No power, no lights, no picture

Ok. sounds like a main board issue. Just to be sure, disconnect the power supply cable from the main board, place a 1k ohm resistor in the end of that connector between 5v and PS_ON. Make sure the resistor isn't touching any metal and plug the TV in. This forces the power supply on with the main board disconnected. Test the voltages after doing this and see if your 12 and 24v lines come up.

[kage]

Re: Sanyo DP46841-00 No power, no lights, no picture

Ok. sounds like a main board issue. Just to be sure, disconnect the power supply cable from the main board, place a 1k ohm resistor in the end of that connector between 5v and PS_ON. Make sure the resistor isn't touching any metal and plug the TV in. This forces the power supply on with the main board disconnected. Test the voltages after doing this and see if your 12 and 24v lines come up.

How can I make that work without a plug of some kind? I can't even get readings without the plug in because I accidentally bridge the connections. The other end of that cable is soldered to the analog board so I cannot remove it.

[zacheriaj]

Re: Sanyo DP46841-00 No power, no lights, no picture

You may be able to carefully solder the resistor in place but make sure its between 5v and PS_ON pins. Also make sure the connector is off. The only thing u need plugged in for this is AC

[lookimback]

Re: Sanyo DP46841-00 No power, no lights, no picture

I worked on one of these a few months ago which had a shorted CPU on the main. The short was between the 3.3v STBY, 1.1v STBY, and ground. Mine was the Z5WJ chassis though. I'm not sure what the difference is.

If yours is the Z5WF, this should be the correct service manual.

If not, you can find it here.

[kage]

Re: Sanyo DP46841-00 No power, no lights, no picture

You may be able to carefully solder the resistor in place but make sure its between 5v and PS_ON pins. Also make sure the connector is off. The only thing u need plugged in for this is AC

I may make a few extensions for things like this.

Something with a small round insulated plug on one end and a gator clip or something on the other end so that I can plug them into the proper pins on the board and then clip the resistor into the clips (making sure it touches nothing metal). Would def come in handy both now and in the future.

[kage]

Re: Sanyo DP46841-00 No power, no lights, no picture

I worked on one of these a few months ago which had a shorted CPU on the main. The short was between the 3.3v STBY, 1.1v STBY, and ground. Mine was the Z5WJ chassis though. I'm not sure what the difference is.

If yours is the Z5WF, this should be the correct service manual.

If not, you can find it here.

I know I haven't gotten to the point of knowing its the main yet but did you trash it or manage to find a main that wasn't a billion dollars? I haven't checked pricing on one so I don't know what they are going for.

[lookimback]

Re: Sanyo DP46841-00 No power, no lights, no picture

Here's the cheapest one on Ebay. Let's hope you can figure out which component is bad and that it's not the CPU.

I think I paid around $80. The version I had was internet capable, so the digital main for it was more expensive than for other versions.

[zacheriaj]

Re: Sanyo DP46841-00 No power, no lights, no picture

I may make a few extensions for things like this.

Something with a small round insulated plug on one end and a gator clip or something on the other end so that I can plug them into the proper pins on the board and then clip the resistor into the clips (making sure it touches nothing metal). Would def come in handy both now and in the future.

any tool you can make that works for common routine tasks is golden IMO. Let me know when you get that tested and if the readings are ok we will move on.

[zacheriaj]

Re: Sanyo DP46841-00 No power, no lights, no picture

Here is from shopjimmy the exact match for the mainboard. Always interesting with some tvs how there are 10 different boards with the same part number or for the same tv yet different subcategory numbers
http://www.shopjimmy.com/sanyo-1lg4b...gital-main.htm

[kage]

Re: Sanyo DP46841-00 No power, no lights, no picture

OK so attached is my 1k jumper

It does work.

24V = 24.1V
12V = 11.9V-12V

I also utilized my butter fingers to do a little low voltage welding.

So is there any way to isolate for sure that the cause is the digital board?

[zacheriaj]

Re: Sanyo DP46841-00 No power, no lights, no picture

the problem definitely is the digital main. If the power supply works when forcing it on but not with the main attached, that shows that the main is failing to send the (PS_ON) signal to the power supply. If you want to begin troubleshooting the main, take some good pictures of it. Otherwise we can try to find you a new one. If you decide to order new, you can take the cover off of the inverter board in the mean time and check for bad caps, blown components, etc. Main board should be the answer though.