Memorex MLT3221 - No Power

[johnnieboy2]

Re: Memorex MLT3221 - No Power

Well, I disconnected the CON3 plug to the board and I get the 5vdc solid as can be. The connector has other voltages listed but since the set is not turning on maybe that's the reason, anyway no other voltages present. ARGGGGGGGG! Maybe my power supply board was good all the time!

[johnnieboy2]

Re: Memorex MLT3221 - No Power

Any suggestions?

[PlainBill]

Re: Memorex MLT3221 - No Power

Any suggestions?

Hopefully you can wing this one on your own. The logical assumption is there is an excessive load on the 5 volt rail on the main board. Try to verify this. Then it becomes a matter of tracing the 5V rail on the main board.

Also, earlier I had noted that there are a pair of power FETs on the cold (output) side of the power supply. Presumably these control the missing voltages. If I recall, there was an obvious control line to turn on these voltages. Do that by pulling the line to 5 volts through a 3.3K resistor.

PlainBill

[johnnieboy2]

Re: Memorex MLT3221 - No Power

Think I'm throwing in the towel, without a schematic this is just a shot in the dark. Thanks for all the help, much appreciated.

[Dgtech]

Re: Memorex MLT3221 - No Power

If it's the power board that is giving you problems, try to find it on ebay. I just found one for $40 for a similar set. I've been messing with this set for about 6 months now, off and on. It finally came down to a transformer that I found was arching and making an audible arching sound.

[johnnieboy2]

Re: Memorex MLT3221 - No Power

If I had any indication of life in this thing, I'd probably continue on. I bought the capacitor kit at ebay and nothing but 5v. Then I saw another kit there that said..."if you bought the cap kit and only get 5v now, buy 'this' kit...for more money than the first one. I thought that was pretty funny...this thing could easily be a money pit. Nothing ventured nothing gained, but this venture has gone far enough. Thanks again.

[Dgtech]

Re: Memorex MLT3221 - No Power

If you feel like searching through schematics... here is a polaroid site that has some service manuals. A few of these sets have the same IPOS 150 power board, I think.

http://www.polaroidsupport.com/polaroid/en_us-sm.html

If you search around, you'll find out that this IPOS 150 power supply is found in many sets.

Memorex, Polaroid, Element, and a couple others.

This service manual is for one of the sets with this type of power supply but as you'll see... it does not have details on the board.

[johnnieboy2]

Re: Memorex MLT3221 - No Power

Thanks, already looked there

[mattmarkgo]

Re: Memorex MLT3221 - No Power

need help!!!good day i have mlt3221 when i plug it i see red led light after a second it goes blank....

[Dgtech]

Re: Memorex MLT3221 - No Power

Did you check the things that were mentioned in the first few pages of this thread? If you've done this already and you still need more advice, post pictures of your power board and we'll go from there.

[mattmarkgo]

Re: Memorex MLT3221 - No Power

i already cheack 5volts,12 volts ok....

[mattmarkgo]

Re: Memorex MLT3221 - No Power

thanks in advance.....

[mattmarkgo]

Re: Memorex MLT3221 - No Power

24 volts ok,when i plug i see a red light i a seconds black screen......

[mattmarkgo]

Re: Memorex MLT3221 - No Power

any suggestions please!!!!!!!

[Dgtech]

Re: Memorex MLT3221 - No Power

what are the voltages that you see all the way across the output connector - in order?

[mattmarkgo]

Re: Memorex MLT3221 - No Power

they have pin1-3v, pin2-5v, pin3-5v, pin4-11.5, pin5-o, pin6-0,pin7-0v,pin8-0v, pin9-23volts in con3,


connector4
pin1 - 3volts
pin2 - 0 volts
pin3 - 0volt
pin4 - 0volt
pin5 - 5volts
pin6 - gnd...

[mattmarkgo]

Re: Memorex MLT3221 - No Power

result of ic2#52722
pin1- 0V
pin2- 7V
pin3- 9V
pin4- 0V
pin5- 14V
pin6- 4V

[mattmarkgo]

Re: Memorex MLT3221 - No Power

resistance to hot ground to pin 1 of IC2 is shorted....need help.......please!!!!!

[Dgtech]

Re: Memorex MLT3221 - No Power

I'm looking around for IC2 but I cannot find it on your picture. Please specify. Also, I recently got a similar set working after I found the transformer above the main cap to be bad. It was arching intermittently. Whenever the set would fail, the LED on the bottom left hand side would come on. I had to replace the whole board cause there were no replacement transformers to be found for this board. Good luck.

[kobkobk]

Re: Memorex MLT3221 - No Power

dear sir
i also got this problem at this power supply
i have checked all the outputs at con3 the tv power on for 2sec and shot off.
at ic8 pin 14i connect 12v constant the back light was on at half power
any suggestion?
thanks
kob