Sanyo DP42849 Backlight Shutsdown

[high-tech]

Classic "2seconds to black"

Here is what I found: This Inverter Transformer has a shorted secondary winding. It has two secondary windings, the shorted one is 27 ohms and the good one is 2.3K ohms. This powersupply board is not available

I have searched for a replacement and can't find one in my limited search abilities. Anybody know where I could get one?

[selldoor]

Re: Sanyo DP42849 Backlight Shutsdown

Are you sure it has two secondary windings ? could one be the primary.
This looks like a big transformer that supplies a series of smaller transformers on an inverter board?

[high-tech]

Re: Sanyo DP42849 Backlight Shutsdown

Yes I'm sure. look just above the transformer and you will see the two plugs where the two backlight harnesses plug into the board.

[tom66]

Re: Sanyo DP42849 Backlight Shutsdown

The main secondary on this appears to be between pin 5 and 10, and it has only one such secondary.

[selldoor]

Re: Sanyo DP42849 Backlight Shutsdown

I remember this one now!! Nightmare thread.
https://www.badcaps.net/forum/showth...DP42849&page=1

Do those "lamp harness" cables go straight to the bulbs or is there another board.

[high-tech]

Re: Sanyo DP42849 Backlight Shutsdown

well I think it is single secondary. and pins 6 and 9 are for the feed back? If this is true my earlier checks that I thought were 2 windings. I ohmed from pins 9 to 10 and got
2.3k ohms and pins 5 and 6 and got 27 ohms. the 27 ohm reading should be infinite or open.

[tom66]

Re: Sanyo DP42849 Backlight Shutsdown

It is single (output) secondary, the other secondary will probably be for monitoring the current.

[high-tech]

Re: Sanyo DP42849 Backlight Shutsdown

I remember this one now!! Nightmare thread.
https://www.badcaps.net/forum/showth...DP42849&page=1

Do those "lamp harness" cables go straight to the bulbs or is there another board.

IDK yet, I only got the small inspection cover off. I dont have the whole back off yet, but I looked up parts list @ shopjimmy and there are no other inverter boards listed for this model. So I'm assuming the two harnesses go directly to the bulbs

[high-tech]

Re: Sanyo DP42849 Backlight Shutsdown

that other secondary for monitoring current is shorted to the main secondary windings by a resistance of 27 ohms between pins 5 and 6. Pins 5 and 10 being main sec and pins 6 and 9 feedback right. so why is pin 5 and 6 got that short? I think its toast

[high-tech]

Re: Sanyo DP42849 Backlight Shutsdown

I remember this one now!! Nightmare thread.
https://www.badcaps.net/forum/showth...DP42849&page=1

Do those "lamp harness" cables go straight to the bulbs or is there another board.

I read that other thread to brother and thats messed up how it all ended and I think he has the same issue with the inv transformer

[tom66]

Re: Sanyo DP42849 Backlight Shutsdown

May be a common tie in point, but the isolation gap would make me think otherwise. It would be rare, but not impossible, for such a failure to occur.

[KJINTF]

Re: Sanyo DP42849 Backlight Shutsdown

Have you made any progress on the inverter transformer issue?

Power / Inverter board data - DPS-260LP A, P/N 1AV4U20C41500
I have the exact same board with a bit different symptom
Upon power on after afew seconds the backlights flash for less than one second
Looks as if the rest of the TV is functioning OK with Video and audio

Pin 9 to 10 measure 370 Ohms
Pin 5 to 6 27 Ohms

[jazpa]

Re: Sanyo DP42849 Backlight Shutsdown

I have model dp42849 sanyo everything works good but the back light i jump the 5 volts to the bl-on and i still have nothing could that be my power board with my inverters built in or what can some one help me with this thanks

[ztu165]

Re: Sanyo DP42849 Backlight Shutsdown

Guys let me jump in here I also have a SANYO DP42849 that powers up normal, but the backlights come on for a second and then turn off. I can hear sound and change channels, but can't see anything. I am new to this, just started a few months ago as a hobby, but it's been getting more and more challenging as I get more TV's. I replaced three mosfets closest to where the backlights connect, but this did not solve my problem.

[ztu165]

Re: Sanyo DP42849 Backlight Shutsdown

Has anyone figured it out yet?

[selldoor]

Re: Sanyo DP42849 Backlight Shutsdown

Has anyone figured it out yet?

There are now 4 of you all with the same problem ,at the same time, so why not get together and do some comparison tests.

In my mind it is probably the inverter transformer - If that drives the bulbs directly ( I keep asking that but dont seem to get an answer) and the bulbs are good then not much else it could be as voltages seem generally good.

I have looked for the transformer before ( failed miserably with a red herring see link to earlier post) and concluded it was a proprietary component and would only be available if a board came available from a tv with a smashed panel. So you all need to keep in touch and hopefully prove me wrong.

[ztu165]

Re: Sanyo DP42849 Backlight Shutsdown

Yes sir, the transformer drives the backlights directly, at least in my TV it does. I hope someone can find the transformers somewhere because I have had enough looking for them.

[KJINTF]

Re: Sanyo DP42849 Backlight Shutsdown

selldoor,

To answer your question
YES - the transformer secondary winding connects directly to the lamps via long cables. Mine has CN4 (pin 10 of transformer) and CN5 (pin #5 of the transformer) connecting

I removed the connectors and placed a know good lamp on the output - No change after 2 seconds or so a very short duration flash of the lamp - nothing more. Additionally mine has some clear indication of excessive heat under the transformer secondary windings - IMO it looks like a very poor design for driving the lamps

I too tend to believe it is the transformer - my static resistance readings are on post #12Plus the clear indication of excessive heat under the secondary windings

Agreed the transformer most likely is a proprietary component - looks like this one is destined to be a parts donor

[martyparish]

Re: Sanyo DP42849 Backlight Shutsdown

Hey guys,

I think there are two options(in my humble opinion)

1) Check this seller out on ebay who is selling "refurbished" PSUs for this TV. $125, but you get $50 core for old board. ($75 ain't too bad I guess)

ebay board

2) Rewind the transformer

[KJINTF]

Re: Sanyo DP42849 Backlight Shutsdown

I just started the second option - "Rewind the transformer"
Will keep you posted