Sanyo DP46840

[kevinm34232]

Re: Sanyo DP46840

http://www.network54.com/Forum/18512...latscreen+Inop

Just found this post seems to be same issue. I would never have found this. Im not sure about the pin layout on the IC he's talking about but I found the 24v in just not sure which leg is supposed to be out...

[budm]

Re: Sanyo DP46840

That is the regulator IC for stepping down the 24vdc from the 24vdc power supply to 13vdc to supply the voltage for the audio amplifiers.
Right now you only have 5Vdc standby circuit working, the 24Vdc circuits are not working, the relay on your power supply board is not either, right? This relay is turn on the the main board to turn on the 24Vdc power supply section.
Do you have the pictures of the bottom side of the power supply board? I need to find out if you are getting PS_ON and the 24Vdc out put or not.

[kevinm34232]

Re: Sanyo DP46840

Im a little confused but... (power supply is still mounted so no pics of bottom yet)... I get 24v to inverter board and Im getting 24v on pin 2 of that audio regulator IC on the main board when I switch TV on.. But he described not getting the 13vdc out of it... Im not sure what pin would be the 13vdc to check and see if this is the problem, but no other pins have 13vdc out. Is that helpful?

[budm]

Re: Sanyo DP46840

OK, I got your TV mixed up with simplytrini, which he does not have the 24Vdc, this is why I want you to start new thread so people like me will not get confused with the questions and the answers.
So can you get the picture of that IC (IC1670 p/n QXXGA0500165P or LV5806MX-TLM-H) of the main board that is mention on the link so I can figure out which is in, out, Ground, control, etc?
OK, I found the spec sheet going by what was said on the link, it is a step down switching regulator.
As you can see on page 3, you need to look at the SW pin which should be connected to the Diode and the OUTPUT inductor, then check and see if it has any output at the output side of the inductor.

[kevinm34232]

Re: Sanyo DP46840

Hope this is OK these things are tiny!

[kevinm34232]

Re: Sanyo DP46840

Sorry here's pic thanks for assistance budm!

[budm]

Re: Sanyo DP46840

If that is the cause of the problem, then you will definitely need to mount that 12V linear regulator on a good size heat sink, since you will be dropping 24vdc down to about 12 or 15 V, it will have quite large voltage drop across the regulator, if the amplifiers draw 1A of current, the regulator will have to dissipate about 12Watts of power (if 12V regulator is used), the heat will be pretty good size. That is why the TV used switching regulator instead of linear regulator.

[budm]

Re: Sanyo DP46840

Great picture, OK, I see the Diode (D1670) and the inductor (L1672).
Check to see if you have about 12vdc on the LEFT side pad of the inductor L1672 as shown in your picture.
By the way, that pad of the inductor should be connected to the positive leg of the electrolytic cap below the inductor, if I am correct.

[budm]

Re: Sanyo DP46840

Be back in about an hour, have to go to the gym.

[kevinm34232]

Re: Sanyo DP46840

OK when TV switched on I get 12-13vdc on the LEFT side pad of L1672 but only for a split second then drops to about 3v and then TV clicks off. And yes it appears that that it is connected to the + leg of the cap below but not 100% sure.

[budm]

Re: Sanyo DP46840

I think it drops out because the 24Vdc (which feeds the regulator) comes on for seconds and then drop out, you can hear the relay drops out also, right? The question is now that why the 24VDC/ Relay drop out, overload? The main board detect shorts?
Let try disconnect the power cables to the inverter board to see if it it will stay on.
The link you found said he was getting 0V output, but you are getting the 12V OK, it just does not stay on.

[kevinm34232]

Re: Sanyo DP46840

OK so going thru the service manual it shows 4 power failure circuits to check:

IC 1630 I'm getting a steady 3.1vdc not 3.3, is that an issue?

Audio.Pow IC1670 is where I think the problem is, gets 24v in, but out is sporatic, winds up at about 3vdc before shutdown.

IC 1660 is good, 9v

Not sure where to look for the 12V circuit??

[kevinm34232]

Re: Sanyo DP46840

OK think I found D1681, is that where I'm pointing?? Have steady 12vdc on the left side.

[kevinm34232]

Re: Sanyo DP46840

I am also just wondering if it's possible to bypass this circuit if I wanted to use external audio??

[budm]

Re: Sanyo DP46840

3.1V output from 3.3V regulator is too low, the regulation should be within 3% or better.
Still not sure about step down power supply that convert 24v to 12 v for the audio circuit,, it may be related to the 3.3V regulator.

[kevinm34232]

Re: Sanyo DP46840

Ahhh Ok so what can I check for the 3.3v? I have the service manual if that will help..

[budm]

Re: Sanyo DP46840

Can you post the service manual, that will be big help to all of us.

[kevinm34232]

Re: Sanyo DP46840

Wont let me u/l the file as a .zip or .pdf, it's about 4mb so I don't know why.

[kevinm34232]

Re: Sanyo DP46840

(By the way went thru the 4 page troubleshooting in the service manual and trouble pointed at the main board)

[budm]

Re: Sanyo DP46840

Yes, it does point to the main board. I did not look at the diagram details yet, in the mean time, did you look at shopjimmy to see how much the replacement board is?

Did you see page 5 and 27 of the service manual and see if all those voltages are present?