Memorex MLT3221 - No Power

[budm]

Re: Memorex MLT3221 - No Power

I have a IPOS 150 rev 3.3.

My R55 resistor is pink ceramic and has gold silver violet yellow bands which digikey identifies as 470 megaohm. The schematic for the board clearly labels R55 as 0.47ohm. To complicate matters my R55 measures 2.1ohm out of circuit. I think I need to replace this resistor but with what value?

You forget to add the resistance of your meter probes to the value of that 0.47 Ohms resistor to get the TOTAL resistance value. The resistor is fine, when they are bad they go open circuit.

[Black Rock City]

Re: Memorex MLT3221 - No Power

I have a IPOS 150 rev 3.3.

My R55 resistor is pink ceramic and has gold silver violet yellow bands which digikey identifies as 470 megaohm. The schematic for the board clearly labels R55 as 0.47ohm. To complicate matters my R55 measures 2.1ohm out of circuit. I think I need to replace this resistor but with what value?

[meszy18]

Re: Memorex MLT3221 - No Power

Hi. I would like to keep the long story short. I got a BUSH TV with a problem: no power.

PSU number: 200-P00-HM150H
Rev.no.: 1.8 2006.11.25

I took it apart to see,what can be the problem. C17 & C18 were blown. I replaced them,then i got power,but no screen. I never checked it with flashlight,but i guess,there could be something,cause the inverter didn't want to work only. The LED on the PSU was flashing every second too. Then I found out, F2 is blown. Replaced it,powered on,but the fuse was blown straight away. I was keep looking for broken parts,then i found out, Q16 & Q17 were gone too. I measured 0.0000 on every ways. Replaced them with F2 and now,Voila,the TV working great. So,just the main things...

Parts to be replaced: C17 & C18: 10uF/450V
Q16 & Q17: FQFP9N50CF
F2: 250V/3.15A

I hope,i could help for a few people,but don't forget,it's my story only. Good luck everyone.

[battlecat]

Re: Memorex MLT3221 - No Power

Hi saw this posts ended ages ago ... Any idea why the tubes would be overdriven ?
My TV is tedelex with the exact board and rev numbers and got it up and running reading all the post and help..but it's white out at the moment. And for some arb reason I have audio on the headphone jack but none on the speakers.volume , channels , menu etc all works.. But seem I have no control... In saying that what voltage should be at the AGN pin , I have my 5v,20v , stdby5v,and 12v... Any ideas would be appreciated. Can't seem to load pics from my iphone..

[dnafix]

Re: Memorex MLT3221 - No Power

I've worked on a few of these and changed the 450v caps but also found that soldering joints on the micro down in the corner by the led on the power supply can keep the inverter from turning on. The soldering joints did not look bad but they were.

[CR Designs]

Re: Memorex MLT3221 - No Power

It was my mistake, you were right about the part number. I checked out those components and found that they were good. I changed the cap just to be sure - same result.

I did find a shorted diode at D10. This diode is marked as HER304. I have circled it on the attatched photo. It is attatched to a heatsink and is standing upright. As also seen in the 2nd photo. This is the classic case of "I thought I checked that before". Taking notes would have made all the difference.

Now I have to find a solution for a match if I cant find the exact component.

Her's a picture of the D10 diode

[fred0927]

Re: Memorex MLT3221 - No Power

Thank you guys, i've been reading the forum for a little while because i have a momorex tv with the same power supply like Dgtech and the same problem so i decided to replace diode
d10 and that was it. Tv working perfect now. Thanks again.

[shorteddiode]

Re: Memorex MLT3221 - No Power

I finally gave up and replaced the power board. Fixed the TV
Thanks for the help

[shorteddiode]

Re: Memorex MLT3221 - No Power

It tested good but I guess changing it is worth a try, I don't have the 5sbv or any voltage on CON3 I guess it just shut down while they were watching it. After seeing all the bulging caps I can understand why. But changing all the caps didn't seem to make a difference. Changing D10 today, I'll let you know what happens

[Dgtech]

Re: Memorex MLT3221 - No Power

You dont even have the 5VSB?

When I had worked on this set I didnt have 5VSB either - Post#5 of this thread. I don't know where that 5V is generated at but I'd change out that D10 to be on the safe side. I dont usually suggest changing parts for the hell of it but it's cheaper than your time is worth getting overly scientific with it.

That D10 "HER304" is a high failure part - or simply stressed due to the faulty design of the circuit. Either way, replacing it was the fix for my set, which is in my bedroom right now. My wife is watching Rachael Ray on it now. I never had any more problems with it. My replacement part was "NTE equivilent - NTE576".

I read somewhere that this part fails whenever the user would try to use this TV as a monitor with the VGA port. Somehow it fails to work as intended.

[shorteddiode]

Re: Memorex MLT3221 - No Power

I have the same problem as dgtech "No power at all. No power LED. No visual or audible changes when plugged in or power button pressed. "CON3" shows no output voltages"
When i first opened it up the capaitors under HS3 were bulged. I have replaced all the elctrolytics on the board, tested all diodes, all transistors, IC2 voltages 1-0, 2-.65mv, 3-0, 4-0, 5-22.04 volts, 6-.1mv. The main cap has 157 across it, I have no resistance between hot ground and pin 1 of IC2. Both fuses are good, I have no power no lights and still no voltage on CON3. All componets have been tested off the board, I even removed and tested
the two transformers for the backlights. The smps trasnformer is E258545 but can't seem to find a data sheet for it. does anyone know how to test it off the board? could this be my problem. Board number IPOS150, same as dgtech. I am stumped and confused

[gb77]

Re: Memorex MLT3221 - No Power

ok, there is no reset other than remove from power for a few minutes & i popped off the back cover and the power supply looks nothing like the 3221 so off to a new thread

[Dgtech]

Re: Memorex MLT3221 - No Power

For best replies and help, I'd suggest starting a new thread with the model number in the title. This makes it easier for people to search and find the thread for this model TV. All of the info related would be in that thread with for that model number.

[gb77]

Memorex MLT4221P troubleshooting

since this is the only thread with a post mentioning a MLT4221P, i'm adding mine. with active inputs to vid2, svid & YPbPr2, powering the tv gets the standby ring to go red. but pushing power or any other button on tv (i dont have remote) changes nothing - red ring, no audio or video. a flashlight has no effect on the screen (no menu or anything). before i take it apart to examine & take pics, etc., i wanted to know if there is a 'reset' procedure for this tv as mentioned above for the 3221, and how to do it. i have only the manual from memorex site for reference so far. if there isn't any useful button pushing i can do, then i'll take the back off for pics & so on. if there isn't anything in common with the 3221 i'll start a new thread. thanks for your help

[johnnieboy2]

Re: Memorex MLT3221 - No Power

Sorry...can you delete this?

[budm]

Re: Memorex MLT3221 - No Power

@johnnieboy2: Please start a new thread for your TV so we will not get confused between the Memorex and your Polaroid even though it may uses the same chassis.

[johnnieboy2]

Re: Memorex MLT3221 - No Power

OK, I had posted quite a few questions and pics here about repairing of a 32" Polaroid HDTV. Plugged in, all I get is a blinking light on the front lower right of front of TV, (no light lit on the P/S board, never got a definite response of what that means. Anyway, the power supply IPOS 150, REV 3.3, only has stand-by 5vdc after I did the multi cap job. I had no outputs off CON3 before cap job, so it helped something. Is there someone HERE who offers repair service at a quotable price. I have seen some ebay auctions that offer a kit of D10 and a 'wire' repair that says it will repair remainder of voltages that are missing, but it is a ridiculous price especially since D10 checks OK, and for me just another shot in the dark. I even see one auction for just a 'wire', now what's that all about? I'm so close to a trip to the garbage dump, and if the set didn't appear like brand new it would already be there. At the end of my 'wire'...

Thanks,

John

[budm]

Re: Memorex MLT3221 - No Power

The one I work on was just the two bad caps, but I usually replace them in a set.
The 8-pin IC is the SMPS Controller IC. If the caps had failed completely, they could have damage the out put MOSFET's due to large AC being applied to the circuits due to no DC filtering.

[plnyberg]

Re: Memorex MLT3221 - No Power

Budm, is that all you had to replace to get the backlight working again?

Also, the first picture of that 8 legged IC, what was that? What was its function and did you have to replace it for the backlight or something else?

Also, this is for everyone, is it possible that the light or lights themselves went bad?

I saw someone selling a power supply on Ebay for testing the florescent tubes in laptop screens... I have to think that the voltage used to drive the backlight in a laptop is lower than in a TV, but it still makes me wonder.

All of the caps are on the way. I still need to test the fets, but if they check out I am going to replace the 10ufs first and try it. (I ordered 4 of them just in case)

Thank you all for the advice and help, this is a great community. I can't wait to dive into the two laptops I have that need to be repaired!

[budm]

Re: Memorex MLT3221 - No Power

By the way, the two 10uf 450vdc caps are for the backlights inverter circuits.