BUSH LED2497ODVDFHD, 17PW80 V2, Dead!

[flocko]

Re: BUSH LED2497ODVDFHD, 17PW80 V2, Dead!

i would still change all five diodes, i up grade them when i repair or you will be back in there in no time,and yes you just beat me to that one on eBay but that life Flocko

[digbyt]

Re: BUSH LED2497ODVDFHD, 17PW80 V2, Dead!

Thanks TOM66 for your advice on this thread, and Andy for starting it.

I have a Sharp LC-24LE240E 24" TV which died about a week after its 12 month warranty expired, so pulled it appart and google's the part number on the power supply board.

That led me to badcaps.net. Andy's symptoms matched mine, and the layout in his photographs looked exactly like my TV. And following TOM66's advice above I found I had exactly the same shorted diode as others have had. Seems to be a real design flaw with these supplies.

Still waiting on the replacement set of diodes I ordered from eBay, but a quick power up test with the offending diode removed brought the TV back to life. About £2.50 for parts plus postage, vs a minimum £30.00 just for a repair quotation! (and I wasn't looking forward to trying to lug a TV into a repair centre).

[digbyt]

Re: BUSH LED2497ODVDFHD, 17PW80 V2, Dead!

One thought - Looking at the data sheet for the UF5402 diode, there seem to be others in the family which have higher max reverse, max rms and max DC blocking voltages, such as the UF5404. Would it help forestall this type of failure to use one of these higher rated items?

Or could such a substitution be likely to cause a problem?

[digbyt]

Re: BUSH LED2497ODVDFHD, 17PW80 V2, Dead!

P.S. By using one, I mean replacing all three of course...

[multimeter]

Re: BUSH LED2497ODVDFHD, 17PW80 V2, Dead!

they will be fine,normally a good upgrade.

[Alastair E]

Re: BUSH LED2497ODVDFHD, 17PW80 V2, Dead!

Would it not be better to use a Single 20A diode to replace the whole lot of those puny things?
--Plenty of room with those 5 out of there....

A BYV34-400 would do it a treat, TO-220 package, add a heatsink and there you go.....

[tom66]

Re: BUSH LED2497ODVDFHD, 17PW80 V2, Dead!

A TO220 would be the best. However that kind of modification would be quite advanced.
It's best to use the original UF5402 as in fact increasing vbr devices have higher forward voltage usually which increases power dissipation

[digbyt]

Re: BUSH LED2497ODVDFHD, 17PW80 V2, Dead!

As support for the UF5404 option was mixed, and a 'quite advanced' option might be over ambitious for a first repair, I decided to play it safe initially and replace the bad D709, plus its paralleled D708 and D710, with a new set of three UF5402's.

I reassembled my Sharp 24" TV last night, and can happily report that it powered up normally and worked perfectly for the hour or so that I had it on.

So thank you BadCaps, and everyone that contributed to this thread!

[tom66]

Re: BUSH LED2497ODVDFHD, 17PW80 V2, Dead!

Glad to hear. You should refer to it as an Alba 24" because it is completely identical, but Sharp charge more for their badge to be glued to the front.

[flocko]

Re: BUSH LED2497ODVDFHD, 17PW80 V2, Dead!

I have repaired lots of these and have found that for a good replacement the ER502 200v 5 amp is well up to the job and you dont have to pay to much for them under £3.00 for twenty including postage from Hong kong Flocko

[oddbodd]

Re: BUSH LED2497ODVDFHD, 17PW80 V2, Dead!

Thanks to this thread, I've just repaired a 10 month old Toshiba 22DL712B with the same 79PW80 v2 power supply.

Exactly the same diode problem, so I replaced the three SB5100 diodes with UF5408 items and a dollop of thermal paste to equalize the temperatures.

I did think of drilling a few holes in the back casing to aid the flow of cooler air over the diodes, but didn't get round to it.

Easy 48hr repair - cost 0.99p.

[wil71]

Re: BUSH LED2497ODVDFHD, 17PW80 V2, Dead!

Hello guys great reading. I have a jvc lt24dg42j which is dead and uses the same power board (which also is dead), I have ordered the caps but was wondering about the epoxy paste, I take its the same stuff as used on processor heatsinks, Can you explain how this would be used please to a newby who likes experimenting.

[wil71]

Re: BUSH LED2497ODVDFHD, 17PW80 V2, Dead!

Hello guys great reading. I have a jvc lt24dg42j which is dead and uses the same power board (which also is dead), I have ordered the Diodes but was wondering about the epoxy paste, I take its the same stuff as used on processor heatsinks, Can you explain how this would be used please to a newby who likes experimenting.

When I say caps i meant Diodes, Sorry, still learning

[diif]

Re: BUSH LED2497ODVDFHD, 17PW80 V2, Dead!

Hello guys great reading. I have a jvc lt24dg42j which is dead and uses the same power board (which also is dead), I have ordered the caps but was wondering about the epoxy paste, I take its the same stuff as used on processor heatsinks, Can you explain how this would be used please to a newby who likes experimenting.

It's different, it's a two part glue mixed in equal parts that sets, as opposed to normal thermal paste that shouldn't set.
Here's what I used for this exact problem. I forgot to take a photo though.

There are two types they sell, Arctic Silver thermal adhesive and the stuff i have the Arctic Alumina, i'd recommend the Alumina as the other becomes slightly capacitive when set.

[wil71]

Re: BUSH LED2497ODVDFHD, 17PW80 V2, Dead!

Does this replace the soldering or is it used in conjuction with it, do you have a link to a good supplier

[tom66]

Re: BUSH LED2497ODVDFHD, 17PW80 V2, Dead!

The devices are still soldered.
After soldering, this is used on the TOP of the board to glue the devices together.
The theory being that if they are matched in temperature, the thermal runaway effect (due to bad design) will be prevented.

[wil71]

Re: BUSH LED2497ODVDFHD, 17PW80 V2, Dead!

Thanks for the valuble info. Good to know. Will get some ordered. Just out of curiosity, what would happen if the diodes were just soldered¿

[tom66]

Re: BUSH LED2497ODVDFHD, 17PW80 V2, Dead!

It would work fine, but within a year i'd expect the same failure to happen.

[diif]

Re: BUSH LED2497ODVDFHD, 17PW80 V2, Dead!

My mistake, i did take a photo.

[wil71]

Re: BUSH LED2497ODVDFHD, 17PW80 V2, Dead!

Excellent thanks for the picture, makes sense to me now.