DPS285BP 5v standby transformer blown

[Hounddoghill]

Sharp TV LC-80LE633U
Power supply board DPS 285BP Run TKB096WJQZ

Standby transformer markings (attached picture)
MP-130I(01)
AV-DP11153 Delta
Dcum 1244(03) H6P

So an event in the primary exploded the cap (C7901)on pin one of the Standby circuit IC. So after replacing a couple diodes a the 2.2ohm resistor(fuse) I found the transformer inputs are open.

Anyone know about replacements for this transformer?
I suspect the original is not available.
https://www.badcaps.net/forum/images/smilies/silly.gif

[R_J]

Re: DPS285BP 5v standby transformer blown

Which pins are you checking on the transformer?

[Hounddoghill]

Re: DPS285BP 5v standby transformer blown

1-2 and 3-4 are both open
5-7 Output still has .1 ohm (6 and 6 windings in parallel)

there is a suggested transformer spec on the data sheet for standby power IC.

1-2 is 72 windings
2-4 is less don't recall

Pretty sure it's dead

[R_J]

Re: DPS285BP 5v standby transformer blown

That's not the configuration, the primary is 2~3, The vcc feedback is 1~4 Pins 5~7 are the secondary.

Also check R7907, and I would also replace C7907 and C7918

[Hounddoghill]

Re: DPS285BP 5v standby transformer blown

good info

2-3 is 2.8 ohm
1-4 is open

should 1-4 be open?

[R_J]

Re: DPS285BP 5v standby transformer blown

No 1~4 should not be open. Check the transformer leg to see if the wire is broken, and also make sure you are making a good connection with your probes

[Hounddoghill]

Re: DPS285BP 5v standby transformer blown

Checked again and 1-4 open and bobbin wires look solid at pins.

So I think I need a replacement plan.

[Hounddoghill]

Re: DPS285BP 5v standby transformer blown

I used my digital microscope and the coil at pin one is burnt.
Second photo is good side.

Anyone ever take one of these part and rewind?
I am going to try and open.

Or know of a a replacement

[daltonjr.]

Re: DPS285BP 5v standby transformer blown

I have exact same transformer from Grundig Tv that is shorted. Have you fixed it, found replacement one or some alternative... ? Thanks!

[daltonjr.]

Re: DPS285BP 5v standby transformer blown

Does anyone know if the two pins on secondary are ment to be shorted / 0 resistance, or that indicates a faulty transformer?

[R_J]

Re: DPS285BP 5v standby transformer blown

You are measuring the DC resistance of the winding, basically a piece of wire, it will check shorted or less than 1Ω

[Clifton11283]

Re: DPS285BP 5v standby transformer blown

I have a similar issue on a DPS-162KP-1A power supply board on a sharp TV. I found fuse F7001, resistor R7900, capacitor C7901, IC7903 blown. Cannot find any further faulty components but when I test the TV with a serial bulb circuit to check for short circuits, the bulb is lighting which means I still have a short circuit somewhere. Any help what can I check further please?

[algutria]

Re: DPS285BP 5v standby transformer blown

5-7 shall be about 16 ohms in a good transformer.
What I did is to buy a power cards for parts in e-bay for 25 dollars. that include the transformer.
Usually when transformer T7901 is shorted 0.0 to 0.2 between terminals 5-7 blows the cap C7817 (1nF) or the input resistor R7900 (2.2 Ohms)

[algutria]

Re: DPS285BP 5v standby transformer blown

Does anyone know if the two pins on secondary are ment to be shorted / 0 resistance, or that indicates a faulty transformer?

It is shorted. Shall be around 16 Ohms in a good transformer terminals 5-7

[R_J]

Re: DPS285BP 5v standby transformer blown

The secondary winding is small and the DC resistance of the wire will be close to 0Ω