Memorex MLT3221 - No Power

[plnyberg]

Re: Memorex MLT3221 - No Power

Thank you for the quick response.

I checked D10 and got .4v one way and the other way it climbed to 1.5v. I will take it out and retest.

Yes, those two caps are slightly domed, one more than the other. I will order them and replace.

[retiredcaps]

Re: Memorex MLT3221 - No Power

I checked D10 and got .4v one way and the other way it climbed to 1.5v. I will take it out and retest.

Those readings indicate the diode is good even though the readings only climb to 1.5V.

Yes, those two caps are slightly domed, one more than the other. I will order them and replace.

Here is my standard answer for people who only think about replacing the obviously bad bloated caps.

https://www.badcaps.net/forum/showpo...84&postcount=3

[plnyberg]

Re: Memorex MLT3221 - No Power

You are right, I was just looking for a kit with all of the caps for that board.

Do I have to just order them separately? I only see one 10uF cap on the badcap.et store, but it is 400v rated. I would like to order from this site since I am getting answers and help from this site But the original caps are 450v, of course they were HEC which is probably why they failed.

So yes, I want to replace all of the caps on the board. Any suggestions of where I can find a kit with GOOD caps? Is there a kit I am not finding on the store here?

[retiredcaps]

Re: Memorex MLT3221 - No Power

I would like to order from this site since I am getting answers and help from this site

The gesture is appreciated since it helps support this forum, but the badcaps.net store is more focused towards motherboards so you are unlikely to find all the caps here.

Most members here like digikey.com. A DIY approach using digikey.com is about 1/2 the cost of an ebay "kit". Shipping from digikey.com, if you are in the USA, is a very reasonable $2.90 or so and you get the caps in about 2 days with first class mail.

[plnyberg]

Re: Memorex MLT3221 - No Power

Ok, thanks. I guess I will be doing a cap inventory on that board tomorrow Unless someone here has already done it?

Edit: I'm not trying to be lazy, just wondering if someone had already put a list together. I did a few searches and could not find one. If I can get a good list together I will post it here. It looks like the replacements for EC17&18 will be a little taller.

[retiredcaps]

Re: Memorex MLT3221 - No Power

Unless someone here has already done it?

Even if someone has done it, it is NOT guaranteed to be correct since manufacturers routinely make revisions and even complete board changes while keeping the same model number. When I fix a monitor, I usually never look at a posted list of caps. It only takes 5 minutes to list the caps and get the dimensions.

With DIY, you are guaranteed to get the correct caps and you can add spares + other items if you wish.

[Dgtech]

Re: Memorex MLT3221 - No Power

I'm just curious about something, plnyberg.

Have you put a flashlight to the screen yet to see if there is a picture behind it? The voltages that you put in your original post all look ok. This would tell me that your only problem is the circuit driving the backlights. Unless you seriously want to pull those heatsinks for the heck of it and change all the caps underneath, I'd stick to the high voltage section first. It is common to change all the caps but not neccessary. Depending on your skill level of desoldering, this could be a nightmare. Retiredcaps is giving you good advice, however in this case, I might change the two caps (10uF @450V) and I'd check the two mosfets involved in that circuit as well.

[budm]

Re: Memorex MLT3221 - No Power

FYI:
http://s807.photobucket.com/albums/y...rex%20MLT3221/

[plnyberg]

Re: Memorex MLT3221 - No Power

DGtech, I have a lot of experience soldering/desoldering, but I am with you... I do not want to do more than needed. I am still ordering the other caps, but I am going to change the two 10uf caps first.

I put a flashlight up to the front of the screen and hit menu on my remote and I could see the menu. Should I try with a tv show? is there a difference in the menu and a picture from a tv channel or movie?

Which to fets are you speaking of? Q16 and 17? I made a few measurements in circuit with the tv on:

Q17 left pin (gate?) 123-125 vdc
center pin 342 vdc

Q16 Center pin 134.4 vdc

Should I make some more measurements? Should I desolder them and test them out of circuit?

I was a little worried about them being bad and possibly blowing those two caps again.

[budm]

Re: Memorex MLT3221 - No Power

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

[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

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.

[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

@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

Sorry...can you delete this?

[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

[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]

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

[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

[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.