Sanyo DP46840

[kevinm34232]

Re: Sanyo DP46840

Yes I did that earlier:

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

and 12V supply is good.
Had 3.1vdc at IC1630 instead of 3.3v
and also erraric readings and Audio Pow

So what can I check at about that low voltage at IC1630?

[budm]

Re: Sanyo DP46840

The switching buck converter IC1630 LV5803M (PAGE 45) can take input from 4.5V ~18V and should maintain the output voltage as determined by the resistors (see spec). So it looks like it is not working properly at this point. Its internal reference voltage may be bad.
I would try a new IC or some sort of 3.3V external power source.

So far I cannot find that 12V regulator that convert 24v to 13v for the audio section as mention on the link.

[selldoor]

Re: Sanyo DP46840

So far I cannot find that 12V regulator that convert 24v to 13v for the audio section as mention on the link.

Do you mean cant find the data sheet?

Is this any help?

[kevinm34232]

Re: Sanyo DP46840

Will this work for that IC1630 or no? It says 5v output.

http://www.mouser.com/ProductDetail/...52bNuFsA%3d%3d

One other interesting thing that makes me think the audio IC is (or atleast part of) the problem: Normally when I turn TV on, it takes about 10 seconds for power failure circuit to shut down. But when I put my DMM on the audio IC to read voltage, the TV shuts down much quicker, around 5 seconds.

[selldoor]

Re: Sanyo DP46840

If you check the data sheet for that product at mouser you will see it is the same as
Budm posted above - so I guess it will be ok. Can you do the external source test before you order - just thinking of postage and minimum order charges, if they apply. My question as I dont know the answer would be can it be more than 3.3v as 3.6v is easier to come by.

[kevinm34232]

Re: Sanyo DP46840

Are you saying to get an external source of around 3.3v dc and apply it to the output pin of IC? Gonna need some more info on how Id do this please.

[budm]

Re: Sanyo DP46840

@selldoor, I mean the location in the service manual, prints are so small.
@kevin, on the link, the guy cut the 12v traces that feed the amplifier, I do not think you will want to do that unless you are confident in doing it. I will have to locate that circuits section in the manual first, my eyes are real bad right now.
For the 3.3V power supply problem, you will have to remove some parts from that 3.3V power supply to be able to inject the external 3.3V into it.

[kevinm34232]

Re: Sanyo DP46840

I feel confident in doing it Im just wondering if the audio IC problem is causing the low voltage on IC1630 or vice versa. Like I said when I test voltage on the audio IC it makes the TV shut down faster like it's adding more of a load or something, I dunno it's just a guess. Is it possible that one circuit is affecting the other?

[selldoor]

Re: Sanyo DP46840

Kevinm, please can you post a link to the Service manual

[kevinm34232]

Re: Sanyo DP46840

I tried to post it it yesterday, it kept failing, I can email you like I did Budm.

[selldoor]

Re: Sanyo DP46840

Yes please - I didnt mean upload it using attachments it will be too big for that
I just meant put the link in a post like

[kevinm34232]

Re: Sanyo DP46840

I don't have a link someone emailed it to me

[selldoor]

Re: Sanyo DP46840

Ok Got SM Thanks - will see if I can split it up

Here are some BIG excerpts for budm.

[selldoor]

Re: Sanyo DP46840

SM Split into 3 zipped sections - all need to be downloaded before it will work.

[mikeknes]

Re: Sanyo DP46840

Hi all, hope all is well. I am wondering if anyone here has had success in fixing this model Sanyo. I am having an issue where the the green led turns on but i cannot get the high voltage for the backlights working, the screen is black and I can turn the tv on/off with the remote and power switch but that is about it. the power supply has: 5v, 15v, 12v & 3.3v. however the HV circuit for the backlight is dead. also I know the inverter board works tried it on another set ant it worked. Any thoughts would be great. Thanks

I have had 3 of these in shop in last 4 months .all with same problem .turned out to be main board in all three

[selldoor]

Re: Sanyo DP46840

I have had 3 of these in shop in last 4 months .all with same problem .turned out to be main board in all three

And...??? What was the fault???

We tend to try for component level repairs on here - board replacement
when we have given up.

Please can you update your profile with country and mains voltage

[kevinm34232]

Re: Sanyo DP46840

I want to give you guys an update here, I've been talking with the guy who did the audio regulator mod on IC1670. He had me cut 2 traces on the actual audio amp IC0001 to isolate it from the regulator and then check voltage on the regulator. The result was voltage was the same, still dropped to <3v instead of 13v, however TV did not shut down. I actually hooked it up and got a picture for the first time. BUT, randomly it will stil shutdown when turning on, it goes further now and backlight comes on, but sometimes will still kick off before video shows. Also, whenever I have my meter on IC1670 to check voltage it shuts TV down, so thinking this is the problem and it's hovering on the cliff now that the amp is disco'd. Obviously I have no audio at this point. So I will try the linear regulator mod and see what happens. Not sure Ill be able to repair those cut traces but oh well, I have surround sound if not

[tom66]

Re: Sanyo DP46840

Cut traces are easy enough to repair. Just strip off the copper plating on each end of the trace and run solder or a small wire across it.

[budm]

Re: Sanyo DP46840

I believe the protection circuits also look at 13v to see it is OK or not, I believe it on page 5.
At least you are getting some where now.

[kevinm34232]

Re: Sanyo DP46840

Yes it does say that it needs 13V for that IC, not sure why TV stays on with 3v, although it gets the 13v for a split second. Lenny's theory is the regulator may not even be able to power the power fail feedback signal..?? Yes getting somewhere I appreciate everyone's help.