Faulty 61in NEC MP1 plasma tv, stuck with a 17in CRT in the lounge

[Securityman]

Re: Faulty 61in NEC MP1 plasma tv, stuck with a 17in CRT in the lounge

Hi there are these ones

Your HK ebay link is for 2.2 K ohms 2.2KΩ
Maplins have them -http://www.maplin.co.uk/7-watt-wirewound-resistor-2179 As you say different format - perhaps solder extension to one side?

There are these ones
http://uk.rs-online.com/web/c/?searc...or+2R2&sra=oss

Dont know what postage is like for small orders looks like £10!!! perhaps you live near a trade counter.

And another http://uk.farnell.com/international-...w-5/dp/1436310

I have looked at CPC as they are just near me but they dont seem to have them or I could have got them for you.

What Wattage are yours

Cheers Selldoor

Got a maplin's around the corner, Rs about 20 min, so not a problem to collect.
Cannot see much on the 2.2 ohm one because it,s very tight.
All i can see is "5A 3, 2.2 ohm, and i think 01 04B.

What voltage will these be?
V X I = W
Is that right to find (W) power

[vinceroger69]

Re: Faulty 61in NEC MP1 plasma tv, stuck with a 17in CRT in the lounge

as tom66 has said the readings on the caps could suggest another item is short circuit it now a matter of finding which one/ones i would also order at least one spare resistor just in case you blow another whilst carrying out tests.

[Securityman]

Re: Faulty 61in NEC MP1 plasma tv, stuck with a 17in CRT in the lounge

Cheers Vinceroger
The bay one,s are in a pack 4, so got that covered.
I have not ordered the others yet, but it looks like Maplins have the same spec one,s so i can pop back if needed.

So what should the caps be sitting at? Above 1 ohm?

[tom66]

Re: Faulty 61in NEC MP1 plasma tv, stuck with a 17in CRT in the lounge

Caps should read above 10 kohm. Preferably above 100k ohm.

You likely have a shorted power MOSFET further down the line. A power MOSFET looks like this:

http://media.digikey.com/photos/Fair...FJA4313RTU.JPG

or this:

http://media.digikey.com/photos/Infi.../SPP70N10L.JPG

They will likely be mounted to a heatsink of some sort, perhaps directly to the plasma panel.

Note you can't work out the power dissipation of these as they are only used when first switched on. Connecting those big 330uF caps to the mains is like shorting the live and neutral together for one cycle of the mains. This trips breakers. The series resistors limit the peak current. They don't get very hot during normal operation.

[vinceroger69]

Re: Faulty 61in NEC MP1 plasma tv, stuck with a 17in CRT in the lounge

tom66 seems good on plasmas i persume above 10kohm i see at a quick look at your pics theres a few diodes on the board 1 by the 2 blue large caps and some on the edge by the resistors you are changing if this was me i would unsolder 1 leg of each of these diodes and test each on on diode test just in case one is short circuit. it should read one way only on diode test.

[Securityman]

Re: Faulty 61in NEC MP1 plasma tv, stuck with a 17in CRT in the lounge

I am having trouble with my k and M ohm readings i think.
On the 200k setting it,s over range. On the 20M setting it read 0.27M ohms
So is that 270k ohms? or 2.70k ohms

I guess the first thing to do is fit the new ceramic resistor that is open and try to power it up?

[vinceroger69]

Re: Faulty 61in NEC MP1 plasma tv, stuck with a 17in CRT in the lounge

in post 8 number 4 pic top left of picture are they the power mosfets there looks like 3 of them not on heat sinks though?

[Securityman]

Re: Faulty 61in NEC MP1 plasma tv, stuck with a 17in CRT in the lounge

that's the board the i have found the open ceramic resistor on.

[vinceroger69]

Re: Faulty 61in NEC MP1 plasma tv, stuck with a 17in CRT in the lounge

not sure if they are the power mosfets can you read the part number on them?

[Securityman]

Re: Faulty 61in NEC MP1 plasma tv, stuck with a 17in CRT in the lounge

Fs20sm
5 1501

I got

"MITSUBISHI Nch POWER MOSFET HIGH-SPEED SWITCHING USE"
from the first Google search

[tom66]

Re: Faulty 61in NEC MP1 plasma tv, stuck with a 17in CRT in the lounge

0.27M is 270k. Sounds okay. I am surprised your Fluke is manual ranging - as all pictures I have seen of the 77 series show it as an autoranging meter.

You might only find out when power is applied. In the worst case, it will simply cause the resistor to fail again. It's unlikely to damage anything further.

[Securityman]

Re: Faulty 61in NEC MP1 plasma tv, stuck with a 17in CRT in the lounge

"set it to manual ranging (the autoranger will be confused by the caps)"
I done this because you said to in a post on post 1.
It is a auto ranging meter, but i pressed the button on the dial to go to manual ranging.
To tell to the truth, i only use the meter to test DC voltage and continuity of cables.
Time to read the user manual for the meter i think.......

[tom66]

Re: Faulty 61in NEC MP1 plasma tv, stuck with a 17in CRT in the lounge

"set it to manual ranging (the autoranger will be confused by the caps)"
I done this because you said to in a post on post 1.
It is a auto ranging meter, but i pressed the button on the dial to go to manual ranging.
To tell to the truth, i only use the meter to test DC voltage and continuity of cables.
Time to read the user manual for the meter i think.......

Yeah I was just wondering whether it did actually have an autoranger. If you see ~270k across caps I say replace the resistors and see if that's all.

[Securityman]

Re: Faulty 61in NEC MP1 plasma tv, stuck with a 17in CRT in the lounge

Looks like its a waiting game for the postman now.
I will update here when i have fitted the resistors.
If anyone has anything else to add, please do.

Thank you Tom, Selldoor and vinceroger for taking the time to help a newbe.
You won't get rid of me that easy as well, see i am a bit of a magpie, so will now find all sorts of panels to open, play with and ask for help from you guys.
But that,s what it's all about i guess.
I get a little buzz when i fault find and get to the bottom of the problem, always with the help of a forum like this.
How hard must it of been before the net to join like minded people together.
Cheers
Sm

[Securityman]

Re: Faulty 61in NEC MP1 plasma tv, stuck with a 17in CRT in the lounge

Well i got some good and bad news.
The 10 ohm one's come today, fast for 2nd class.
I have not got the 2.2 ohm one yet, but could not wait so i fitted the open one and the one next to it.
The panel now works, but shuts itself off after 58 seconds and the green light goes to steady red.
I have it sitting on two foam blocks about 20mm from the floor with the back off. This is ok to test the panel like this i take it?

Update: Forget that, i think it,s working.
Is it ok to leave it on test on the foam blocks? If so how long is ok?

What the problem was, this panel has split screen, but when you only have one input and the other side is "no video" the panel shuts down after 1 min. Because i only have it 20mm from the ground, only had a little mirror one corner and could not see it was in split screen mode. I have just been out to the garage after about 5 min and its still running.

Update: Still running after 10 min. i cannot believe a 50p component has saved this panel from the dump and a complete newbie like me has got it running, of course i could not of done it on my own.
Time for me to pay my subs to the bad caps server fund i think.


Tom666 your are the man, what a super star. Fixed from looking at a pic on your first try.

[tom66]

Re: Faulty 61in NEC MP1 plasma tv, stuck with a 17in CRT in the lounge

Well, that's pretty amazing! I'm glad you fixed it. Now replace the others before it goes again!

Plasma TVs rely on convection cooling (hot air rising through heatsinks) to keep them cool. So you shouldn't lie them down too long, or they can overheat. I would imagine 5 minutes on for every 10 minutes off would be fine. If you aren't displaying a bright picture I'd imagine you could leave them lying down indefinitely as they don't use much power with pixels dark.

Now I want a 61" NEC plasma to fix ! How an earth would I get that in my dad's 206?

[Securityman]

Re: Faulty 61in NEC MP1 plasma tv, stuck with a 17in CRT in the lounge

Well i am back with bad news.
I had the panel running until 2am last night from about 5pm, switched it on and of a couple of time's. Max off time about 20 min.
Switched it off last night a 2am, tried it at 9am and it,s doing them same as before, just the green power LED on.

Tested the ceramic resistors and number 1 the 10 ohm one is open circuit again.
So it looks like it was ok when new, was fine running for 9hrs, but as soon as it was switched off for longer than about 20in, the start up when cold popped it.

I have changed number 1 and 2 the 10 ohm one's again but need to find out why the replacements popped.

Would you say it's a fault on the PSU board? Just to narrow the search from the other boards.
Any help would be great guys and girls (if there are any on here).

Cheers
SM

Any help guys would be great.

Update: I did not change the 2.2 ohm one because i did not have it here, so thought i would test it first with out changing it.
would that of made any difference do you think?

[tom66]

Re: Faulty 61in NEC MP1 plasma tv, stuck with a 17in CRT in the lounge

I think the resistor may have just opened because it's not designed for the high surge current. You could try replacing it with a higher wattage one or using one marked specifically for high surge current.

[Securityman]

Re: Faulty 61in NEC MP1 plasma tv, stuck with a 17in CRT in the lounge

How high wattage should i try? I can get from RS, 7W, 11W, 17W

http://uk.rs-online.com/web/c/passiv...n=Power+Rating

Cannot see one for high current surge, got a link to any?

[tom66]

Re: Faulty 61in NEC MP1 plasma tv, stuck with a 17in CRT in the lounge

These may be okay, but I'm not certain. No datasheet as far as I can see!

http://uk.rs-online.com/web/p/throug...fixed/1998059/