Acer 42" LCD tv no power or stdby light

[giannioscar]

Re: Acer 42" LCD tv no power or stdby light

Hello sorry but I ask for a courtesy Information I the Same Problem with acer I replaced everything EXCEPT dla001d What I do not find I replaced the piece with L6598D But as I put the legs and went in short you could help me with Hello

[giannioscar]

Re: Acer 42" LCD tv no power or stdby light

ciao scusate ma chiedo per cortesia una informazione ho lo stesso problema con acer ho sostituito tutto tranne dla001d che non trovo ho sostituito il pezzo con l6598d ma come ho appoggiato i piedini e andato in corto potreste aiutarmi grazie ciao

[Maxamus58]

Re: Acer 42" LCD tv no power or stdby light

Thanks budm. I bought this Acer for $150 figuring it to be a relatively simple repair being a power board issue only. The symptoms are that it takes several on/off before the backlight kicks in and a couple more before the tuning circuit settles and I get a clear picture. The input connectors are in poor condition which suggested to me that there was power leakage. After finding this thread and searching for replacement boards I actually found a second TV same model on ebay close by and picked it up for $30. It's connectors are in good nick and it has the same problem but with an extra twist that once up and running but before it is properly warmed it will freeze on garbled screen and emits a full volume banshee scream lol. I'll post back my results.

[budm]

Re: Acer 42" LCD tv no power or stdby light

200C is too low.
sincde when hot air leave the nozzle, it will cool down a bit so you will have to set it a little higer.

http://electronics.stackexchange.com...air-rework-gun

[Maxamus58]

Re: Acer 42" LCD tv no power or stdby light

I am planning to replace this same IC on my 42" Acer. I have a rework station but I am not seeing any softening of the solder at 200 C (air) can anyone point me to a description of the best method of replacing this SMD. I'd like to know what temperature is safe and how long before I should expect to see the solder soften.

ChipQuik seems great but a little expensive for only occassional repairs.

[brnrubbr]

Re: Acer 42" LCD tv no power or stdby light

FYI, narrowed down an issue for a 42" Vizio to a bad DLA001D. Replaced the IC with a STMicroelectronics L6598D. All is well!

Issue: 5VDC good, 12VDC bad, 24VDC bad on power board.

[budm]

Re: Acer 42" LCD tv no power or stdby light

Thanks for the repair feedback, great work getting it working again.
Can you give the link to where you get the IC from?

[slowcap]

Re: Acer 42" LCD tv no power or stdby light

well its time for an update, I received the ic300 chip for $4 including shipping to New Zealand, soldered it in and tried it out, guess what. Its fixed and back to itself, thank you very much Budm for your help and diagnosis.

[budm]

Re: Acer 42" LCD tv no power or stdby light

Did you look REAL close at all the resistors and Diode on the output pins of the IC which drive the Gate of the MOSFETs, when MOSFET shorted out that bad, those components will be damaged also.

[slowcap]

Re: Acer 42" LCD tv no power or stdby light

I have ordered a new ic300 chip, it part number is DLA001D pwm controller, will update when I put it in.

[slowcap]

Re: Acer 42" LCD tv no power or stdby light

Is that the ic300 ?

[budm]

Re: Acer 42" LCD tv no power or stdby light

The PFC is working but the 12/24V SMPS IC is not working.

[slowcap]

Re: Acer 42" LCD tv no power or stdby light

hi, I did follow both gates and both go to the IC300, I soldered a wire to the +ive and the -ive side of the large cap and checked the voltage when pluged in, and its 349 at rest then 415vdc when turned on

[budm]

Re: Acer 42" LCD tv no power or stdby light

You can still have bad SMPS IC300 hwich drives the MOSFETs. Did you trace out the connection and components as I suggested between the Gate and the output Gate drives of the SMPS IC.
Do you also get 380VDC on that large filter cap on the hot side when you power up the TV?

[slowcap]

Re: Acer 42" LCD tv no power or stdby light

UPDATE:

receiver the new mosfet's today, decided to not replace the driver ic as was willing to take the risk, soldered in the new fets and the old bridge rectifier, new fuse and plugged it in, to my surprise no pops or explosions, and the standby light is now on, so I pressed the power button on the remote and the light turned green, and that was it, no picture and no sound, I checked and there is no 24v for backlight and no 12v from power board, so all I have is 5v, there is .4v on the 24v line from the board to backlight, where to next? , I have bought a 2 channel oscilloscope , just waiting on a 100mhz probe. will now search for now 24v power problems while awaiting for a reply.

[budm]

Re: Acer 42" LCD tv no power or stdby light

Just trace out the connections from the Gates back to the IC pins. You should get the P/N of that SMPS IC to get the pin out.

[slowcap]

Re: Acer 42" LCD tv no power or stdby light

Ok , will replace the ic aswell, which are the gate drive diode and resistor that I should check/replace? ,
here are some much better pics, with same phone but with sunlight.

[ben7]

Re: Acer 42" LCD tv no power or stdby light

You better replace the IC rather than taking a chance of blowing up your new MOSFETs. I ave a feeling the Gate drive components (didoe, resistors) are likely to be damaged when about 400V is dumped (shorted Drain to Gate) through those sections.

Agreed!

[budm]

Re: Acer 42" LCD tv no power or stdby light

You better replace the IC rather than taking a chance of blowing up your new MOSFETs. I ave a feeling the Gate drive components (didoe, resistors) are likely to be damaged when about 400V is dumped (shorted Drain to Gate) through those sections.

[ben7]

Re: Acer 42" LCD tv no power or stdby light

That is exactly what seems to be happening, is there a way to test the gate drive circuit with the mosfets removed?, as I'm having to import them from uk to newzealand would rarer not blow up some new ones, I am looking to buy an oscilloscope in a couple of weeks, no help right now of course.

It's far fetched, but we probably could figure out some similar mosfet that you could use as a replacement. That way you don't have to ship things across the world!

Be sure to check the bridge rectifier to see if it is shorted or not. Also check the fuse, if you haven't already.

Refer to post number 13, budm is right about replacing all the parts involved with the mosfets.