NEC Multisync 95 (Model #N903) Monitor...relay clicking

[braincambre500]

Hello all,

I have a NEC Multisync 95 Monitor that when plugged in...the green LED does not come on...plus ther is a clicking sound (sound like a relay) somewhere in the fron section of the PCB, right behind the ON/OFF button.

Does anyone have a clue what went bad on my PCB...as I have a soldering iron ready to go. I'm an electronic hobbiest...but my hobby pertains mainly to FM receivers/transmitters.

Any help would be commended.

a friend, Patrick

[grantspain]

it sound like the monitor power supply is in trip or something to do with the signal input.check for dry solder joints on the chassis and then check the horizontal output transistor for dead short from collector to ground
what happens if you fire up without the vga signal connected?

[Hello my friend...]

Hello my friend,

Yes, thank you very much for responding. I am glad I've got someone who has a keener sence of what is going on. I want to say this...

I make small LPFM transmitters and receivers...and am good at desoldering and soldering replacement components to a PCB. But I not well-bread on knowing where the horizontal transistor is on the PCB. If you could possibly direct me where on the board it is, I can then take it out, and check it with my transistor checker.

I unplugged the monitor from my computer, but still had the power on. And I still hearing that clicking sound coming from the relay. No matter if I have the monitor connected to the computer, or not, it still does not show my greeen LED light , plus the clicking sound.

Looking forward to hearing from you...my wise one!

Sincerely,

Patrick

[grantspain]

i will have to look for the schematics of the chassis first and then identify the h.o.t,i will see what i can find for you iguess the transistor is gonna be something like bu2727af

[Hello my friend...]

Hello my friend,

Yes, I disconnected the chassis, as best I could, and flipped it over to see if I could find Q502. The reason I was looking for the Q502 because someone has a similar problem, and advice was given that the horizontal transistor (Q502) was probably the culprit.

But I looked, looked, and looked at the chassis...and could not find Q502. I saw Q503/Q504/Q505/Q506 and Q507...but could not spot Q502.

I figured Q502 was be rather close to Q503...but again, my magnifying glass did not find it.

I look forward to your reply, my friend...as this would be a great Christmas present if I could find the culprit.

Thank you again, for being considerate and helping me out.

...the cajun boy!

Patrick

[grantspain]

without the schematic of the chassis i can't tell you where the h.o.t is BUT the hot is a bloody big transistor that is clipped or bolted onto the heat shield,it can be found inline of the yoke plug.
btw your model number does not show up on searches
how old is this monitor?

[Hello my friend...]

Hello my friend,

The monitor was given to me...I do not know how old it is...but it looks like it's in great shape...or was taken care of very well.

I will look into the inline yoke area and try and find that transistor. If I do think I found it, I will take a picture of it and send it to you...

...your friend, Patrick

[Hello my friend...]

Hello my friend,

Yes, I believe I found it. Take a look at this picture...

http://earthground.8m.com/C5411.jpg

If you can't get there that way...just copy and paste:

h**p://earthground.8m.com/C5411.jpg

replace ** with tt

Well, if this is the correct horizontal transistor, it is Q504 on the board...not Q502.

From here, I want to say, I have a good multi-meter, and am good at checking things out...but with advice from someone who knows and understands this circuitry...on telling me what to check.

I am apt not to take the transistor out...as I have gone to different archieves in different forums...and found out that the 'clicking sound' meant other/different components were the culprit.

So I am asking...what do you think. I will take your advice, as I have no one else to talk to about this concern.

...your friend, Patrick

[Hello again my friend...]

Hello,

Yes, that address is no good. Here is the correct address of the picture I took of the said transistor.

http://earthground.8m.com/NEC Multisync 95.htm

I will post this and see if this works...

...your friend, Patrick

[Last but now least...]

Let me try again...

Go ahead copy and paste...

h**p://earthground.8m.com/NEC Multisync 95.htm

just replace the ** with tt

This will work!

...your friend, Patrick

[grantspain]

yes that looks correct,this is the most likely cause of your fault BUT other things can cause that like faulty caps,flyback transformer or diodes
if this monitor is more  than a few years old then its very likely it will need a full electrolitic capacitor kit
start at the transistor and remember when you replace it you must have some heat conductive compound between the transistor and the metal frame otherwise it will overheat too quick and shutdown
why do you keep changing your username?

[braincambre500]

Hello my friend,

Yes, seems like I have been changing the name alot. I did not mean too. I thought that was the title for the new post. I will keep it braincambre500. Thank you for seeing that...

Well, I read what you had to say. So my next question is...where do I purchase a 'full electrolytic capacitor kit'....or are you saying that I need to change out a few more components other then the transistor itself. If so, do let me know what I need to change and I will go ahead and purchase these items. I usually use Mouser Electronics for purchasing components.

Since you do not have a schematic on this model...how would I (and you) know what capacitors/diodes/transformers I would have to change? I could put up another closeup picture of the area concerned...would that help you figuring out what I need to also change...besides the transistor?

And yes, I have heatsink compound...as I always use that cream whenever I have a transistor that is attached to a heatsink.

Well, my eyes are getting tired...off to bed I go. Thank you again for taking the time to listen to my plea...it seems as though I am getting closer to getting the ole' screen up and running!

...your friend, Patrick

[grantspain]

you can purchase all the capacitors individually from any supplier all you need to know are the value which are written on the side of them e.g 250v 22uf,common sense denotes that any electrolitic cap that is close to a heat source will fail in time(e.g next to a large resistor or close to a heat shield)
i would just concentrate on the h.o.t for now as this maybe a tv tech job,some psu or frame faults can be very difficult to identify,i am just giving you the most likely component failure
if you changed the flyback,all the electrolitics and the h.o.t and it still did not work i guess you would be a bit annoyed
if you google the transistor number you will see some very interesting info from techs with similar faults

[braincambre500]

Hello my friend,

I could not go to sleep until I desoldered that  C5411 horizontal transistor out of the chassis...and find out whether it was bad or not.

Well...it is not bad.

It's a NPN transistor, and I put my diode checker on it...as I do all transistors...and it gave me a .476 from the neg emitter to positive base...and then it gave me a .512 from the neg collector to positive base.

Well...where should I go from here?

...your friend, Patrick

P.S. When I wake up, I'll read your response, my friend!

[grantspain]

difficult to say where to go on this one,if you're good with your meter you could check some voltages in the psu.best way forward maybe changing the electrolitics in the psu and check all the diodes,also look for any burnt components
if you have a cap tester then check all the caps
this one could be a tv repair tech job,without any documents its difficult to say what to do
but there again it depends how much time and money you want to throw at this
are you sure its that model number

[braincambre500]

Good Morning,

Just woke up...

and read what you had to say. Yes, the back of the monitor says...

NEC Multisync 95 100-120V/200-240V~50-60 Hz 2.2A Model:N903

With my multi-meter, I know how to check capacitors/diodes/transistors...but I just don't know which ones to check on the PCB. Like you have stated, without a schematic, I am not knowledgeable enough to know which ones to check on the board.

And yes, I could check some voltages on the board...but again...I do not know 'where' to check...

Would it be best to do this...

Purchase a schematic for the monitor...and that way it would give me all the crtieria I need in order to check for voltages/capacitors/diodes etc...

I'll let you decide which way I should go from here, my friend.

...your friend, Patrick

Oh...I could take closeup pictures of the area involved, and let you see them...then you could tell me which components to take out and check/voltages to check. I have a good digital camera...and it can take pictures up to 1/4" away...

[AKA Kaytrim]

Here is a link to NEC's support page.  They have live help online look for the link at the bottom of the left column on the page.  It was a real long URL so I used tinyurl.com to shrink it.

http://tinyurl.com/y8mvvb

They might be able to give you a schematic for your monitor.

TTFN 
Kaytrim

[braincambre500]

Hello Kaytrim,

Yes, I called NEC, and they said, even though they do not sell schematics of their units, they did give me a website address to look at...but I called that website on the phone, and he said that they just carry schematics for VCRs and TVs...as they do not have a demand for monitor schematics.

Oh well, looks like I've come to the point where...I can just take out components near the horizontal transistor, and start checking for bad parts.

I want to thank you and also 'my good friend' who has stayed by my side on this quest...I really appreciated that.

Should there be anything else y'all might want to say...my ears are still listening!

...your friend,  Patrick

                 A Merry Christmas and a Happy New Year to All ! ! !

[AKA Kaytrim]

There is one final place you could try, Bob Roberts.  His web address is http://therealbobroberts.net/.

Good luck with the monitor.

TTFN 
Kaytrim

[braincambre500]

Hello 'my friend' and Kaytrim,

Yes, thank you for that website address for the possibility of a schematic.

Well, possibly good news!

I took out the adjacent diode next to the horizontal transistor, and it was bad!

Please do take a look at these pictures I took, and come up with your own conclusion. Could it have been the diode all along? And if so, what cross-ref diode could I use to replace the original one?

Please go to...

http://earthground.8m.com/NECMultisync95.htm

I will wait for comments...

...your friend, Patrick

[grantspain]

can't get the link, my anti spyware is blocking it

[braincambre500]

Hello my friend,

Yes, let me tell you what the diode says on it. That way you can possibly let me know what kind of diode are we talking about...

It says...on 3 different rows...

2F
WN
1.1

That's all it says...I wonder if it's a rectifier?

Hoping to hear from you, my friend!

...your friend, Patrick

[braincambre500]

Hello again,

Yes, sorry about posting on a 'new' post.

I wanted to say that the anode end of the diode seems to be going directly into the base of the C5411 horizontal transistor.

Patrick