Memorex MLT3221 - No Power

[retiredcaps]

Re: Memorex MLT3221 - No Power

You didn't ask, but I'm showing from .6 to 2.0 volts fluctuation on 5v standby.

See post #4 re startup capacitor underneath the heatsink.

[johnnieboy2]

Re: Memorex MLT3221 - No Power

Another bit of background info...The set was given to me and I have no idea what the initial problem might have been. The set is as clean as new all over, no signs of burned components or smoke stains/smell. Just that blinking red LED in the lower right front of set and nothing when 'power on' button pushed...no remote. As for me I know my way around an electronic circuit as long as I've got a signal/power path to follow. In the old days we had Sam's Photofacts to guide us in situations like this. Thanks to you for providing this help site!

[johnnieboy2]

Re: Memorex MLT3221 - No Power

around 315 volts, pretty steady on the cap to ground and 400vdc across the cap...fluctuates around 312-320 on both sides of the fuse. What's the significance of the blinking red LED on front of the TV, not seen any reference to this indicator.

You didn't ask, but I'm showing from .6 to 2.0 volts fluctuation on 5v standby.

[Dgtech]

Re: Memorex MLT3221 - No Power

The green fuse is between the big cap and the transformer. Check both sides with a voltmeter. DC Voltage

[johnnieboy2]

Re: Memorex MLT3221 - No Power

Polaroid TDA-03211C...will not turn on, LED on P/S is off, front LED blinks

[Dgtech]

Re: Memorex MLT3221 - No Power

What voltage (DC) do you have on the green fuse in the middle of the board?

If no voltage there, check the voltage (DC) on the main cap?

[retiredcaps]

Re: Memorex MLT3221 - No Power

Where do I begin?

Post pictures of your board in the same format and composition as Dgtech in post #1.

See my sig file above in the previous post for instructions and limitations.

[johnnieboy2]

Re: Memorex MLT3221 - No Power

Hi, I think I need to jump in here. IPOS Rev 3.3 board, as discussed here, on this Polaroid 32" model. Set will do nothing, tried to turn on with push button on side of set since I have no remote. When it's plugged in, the red light in lower right front blinks consistently, that's all. Red light on P/S board is off...don't know where to start, except to say I have checked the most notable caps, diodes and fuses and all seems well. There is no 5v of anykind. I can hear a faint 'tick' coming from the P/S board about the same duration of the front LED blink... Where do I begin?

[retiredcaps]

Re: Memorex MLT3221 - No Power

It looks like the brown colored caps are bloated from the top down view. If you have a multimeter that can measure uF, I would desolder them and measure uF.

[WY3XinSC]

Re: Memorex MLT3221 - No Power

Whole board photo

[WY3XinSC]

Re: Memorex MLT3221 - No Power

They look unremarkable, really nothing domed-looking about them. Here are those photos. Thanks, -Web

[retiredcaps]

Re: Memorex MLT3221 - No Power

What about EC7, EC8 and EC17 (the ones that I wanted to see) in post #56?

In fact, please post a picture of the entire power board (top down view).

[WY3XinSC]

Re: Memorex MLT3221 - No Power

Here are two photos of the capacitor that I suspect may be bad. I think doming is obvious, but is it possible that it was manufactured like this?

I checked the voltage at this cap- 165V spot-on with the set on, and on the 5VSB test point, definitely 5.110 volts is present. When the set is turned on, definitely 5.110 volts on the 5V test point.

Thanks, -Web

[retiredcaps]

Re: Memorex MLT3221 - No Power

EC17 has an ever-so-slight appearance that it may have domed. EC7 and EC8 to the right of L6 look OK and pass the DVM charge test

Post pictures following the guidelines in my sig file below for a 2nd opinion on whether your caps are bad or not. The test you are doing doesn't accurately measure uF and ESR.

[WY3XinSC]

Re: Memorex MLT3221 - No Power

I'm working on this same TV. The red LED on the power supply board blinks about once a second when the set is on. It has sound, but the backlight does not appear to come on. The large EC2 cap has a dome on top, which I normally associate with a bad cap, but it passes doing the "reverse-the-DVM-leads-and-see-if-it-charges" test. There is no burnt odor to indicate anything really bad happened. I checked all the diodes on the front side of the board, and the zener, and they seem OK. EC17 has an ever-so-slight appearance that it may have domed. EC7 and EC8 to the right of L6 look OK and pass the DVM charge test. Any thoughts of what to check next? This is the same revision board as shown earlier in the thread- dated 2006.11.25. Any assistance would be appreciated. It belongs to an elderly lady who is bedridden, and I'm trying to "save" it for her.

-Web in Myrtle Beach, SC

[Dgtech]

Re: Memorex MLT3221 - No Power

I replaced it with a 5 amp 250 volt slow blow and the other fuse blew down by the power cord rated at 4 amps 250 v slow blow.

I'm not the best troubleshooter but you need to replace the original fuse with the same amperage fuse or you will damage the set. If you're lucky, you'd hope that the main 4 amp was the only thing that blew. The main fuse (near the power plug in) is more than the fuse of the power board itself.

When a fuse blows, it's not the fuse's fault. It doesn't simply blow for the fun of it. If a fuse blows then there is a real problem. Usually a direct short causing it to blow. The amperage rating is set so that if anything in the circuit would cause the current to go higher than the circuit's supply fuse, it will open up, blocking any higher current to go through. If you put a higher rated fuse in there, you're just allowing that current to go through. Doing so may damage something.

In the middle of the board I think there is a fuse called (F2). Check this one as well. I am simply assuming at this point because your model number differs from the one that i had and you didn't post any pictures of your board. I guess you may do that soon. This could help us help you fix the problem.

[tippysolon]

Re: Memorex MLT3221 - No Power

so i've been studying all sorts of youtube videos, this forum, other websites, combined with my generally good understanding of electricity and remedial knowledge of elctronics having experienced a problem with my memorex mlt4221p. the red standby light was on as usual and when i turned it on, instead of powering up like it should do, the light just went out and the tv is dead. took it apart and found the fuse up inside the tv on the power supply board thingy was bad....I replaced it with a 5 amp 250 volt slow blow and the other fuse blew down by the power cord rated at 4 amps 250 v slow blow. replaced that one but did not try powering it up since i figured there must be a fault in the circuitry causing the problem....after studying bad capacitors on youtube i did a visual inspection of the caps to see if there were any visual signs of bad caps...none were noted. i also looked for other visual signs of bad components but couldn't see anything....so, any suggestions as to where/how i should start troubleshooting?

[aaronpass]

Re: Memorex MLT3221 - No Power

Nevermind!! I took it back apart and put the other cap that wasn't bad back in, and blew it out any dust on the board and inside of the tv really good and put it all back together and its working great, thank you!!!!!!

[aaronpass]

Re: Memorex MLT3221 - No Power

Ok i replaced both caps 10uf 450v as recommended put it all back together one blew. Is there something that caused that or could be just have been a bad cap that i got?

[aaronpass]

Re: Memorex MLT3221 - No Power

They are 10uF 450v

Where is the best place to purchase these caps? i have the same tv with the same problem and would like to give it a shot fixing it!! The tv was given to me, they said smoke came out of the top so they unplugged it and were gonna throw it out. So i took it and figured i would try to fix it, "im a tinker bug" This forum rocks!!! I hope to be able to get it going!