1800FP Green light on but no image on screen

[Welchs101]

Re: 1800FP Green light on but no image on screen

Another update.

I took the logic board out of the "bad" monitor and put it into my working monitor. No surprise, my working monitor with the "bad" logic board in it did not work.

So its definite.....the logic board is the problem.

Now, i need to figure out if its worth fixing.........any ideas?

[jetadm123]

Re: 1800FP Green light on but no image on screen

Another update.

I took the logic board out of the "bad" monitor and put it into my working monitor. No surprise, my working monitor with the "bad" logic board in it did not work.

So its definite.....the logic board is the problem.

Now, i need to figure out if its worth fixing.........any ideas?

You can try the fix the severach used on the link below, post #12:

https://www.badcaps.net/forum/showth...0fp+logic+card

It involves replacing two 10uf caps, C739 and C207. You can use regular electrolytic caps as replacements.

Eventhough your logic card is an earlier model, it might be worth a try. Just be careful when you unsolder the original surface mount caps off the board. There are two tabs, one on each side of the cap. Heat each tab and lift gently. You may have to use a rocking motion, but gently as you dont want to lift the solder pads off the board.

[Welchs101]

Re: 1800FP Green light on but no image on screen

do you think i need to replace those two or could i just solder two in parallel with those two 10uf caps, C739 and C207?

[jetadm123]

Re: 1800FP Green light on but no image on screen

do you think i need to replace those two or could i just solder two in parallel with those two 10uf caps, C739 and C207?

Replace. Putting another cap in parallel will only increase the capacitance.

[Th3_uN1Qu3]

Re: 1800FP Green light on but no image on screen

But it will decrease the ESR too. If the originals aren't shorted, yes you can try just soldering them in parallel.

[Welchs101]

Re: 1800FP Green light on but no image on screen

ok. I removed after much effort the two surface mount capacitors (C207 and C739). I replaced them with electrolytic 10uF/50V caps.

Still did not work.

Anyone have any other ideas? I feel like i am shooting in the dark on this one.

[steve2]

Re: 1800FP Green light on but no image on screen

I have looked at this some. Your pic readings shows pin 7 (R as you marked it) as having 5vdc on the bad monitor and 0 on the good. Pin 7 of J702 is the dim adj signal. Page 33 of manual. Does that vary when you dim it, or can you dim it?

[Welchs101]

Re: 1800FP Green light on but no image on screen

steve,

i am not sure how to dim it given that i can not see an image on the screen. To dim it i would need to hit the menu button and then dim it ........right?

thanks for looking at this....i really appreciate it.

[jetadm123]

Re: 1800FP Green light on but no image on screen

I have looked at this some. Your pic readings shows pin 7 (R as you marked it) as having 5vdc on the bad monitor and 0 on the good. Pin 7 of J702 is the dim adj signal. Page 33 of manual. Does that vary when you dim it, or can you dim it?

Interesting observation by steve2. After you've rotated the schematic counterclockwise on page 29 , on the lower right side of the service manual, you will notice that cap C207 (the one you replaced) is part of the dimming adj circuit. Maybe you can check the other components of the dimming circuit for shorts, etc.

[Welchs101]

Re: 1800FP Green light on but no image on screen

i will give that a look. Page 29?

[Welchs101]

Re: 1800FP Green light on but no image on screen

where do you see C207? i dont see it?

[jetadm123]

Re: 1800FP Green light on but no image on screen

where do you see C207? i dont see it?

Apparently, there's multiple versions of the service guide. The one I'm referencing is the 1800FP CL-42 located here:

[steve2]

Re: 1800FP Green light on but no image on screen

That looks like the correct service manual. The one I posted didn't have the C207 and C739 as electrolytics. The reason I looked at this part of circuit is pin 7 of J702 reads 5vdc on bad monitor and 0 on good monitor. My first instinct was a transistor not turning on, but couldn't find it on my manual. Your manual shows Q201 right there in the dimming circuit. The 5 volts is going right thru r206 and r205 to pin 7 of J702. The transistor could be bad or the base is not getting turned on.

[Welchs101]

Re: 1800FP Green light on but no image on screen

I followed the link you sent for the manual...........i cant seem to download it. Is it possible you can post just the pdf file?

[steve2]

Re: 1800FP Green light on but no image on screen

I had the same problem downloading it. Then I put the model # in the search box and when it came back up, it had a download button, which then worked. I tried to post the pdf manual here, but it failed twice in a row. It is less than 3 mb and themax allowed is 9mb, so I can email it to you if you want or can't get it to download.

[Welchs101]

Re: 1800FP Green light on but no image on screen

steve,

i emailed you with my email address. Please do send it to me if you can.

[steve2]

Re: 1800FP Green light on but no image on screen

I sent it a few hours ago. I just re-sent now at 2.35 The first one may be in your spam/junk folder. Let me know if you get this one.

[Welchs101]

Re: 1800FP Green light on but no image on screen

i checked the bjt that was near the C207.......it looks fine. I also compared the reading i measured for the bjt to the reading i measured on the "good" monitor and they were the same.

[Welchs101]

Re: 1800FP Green light on but no image on screen

Just a thought.......if the EEPROM were "bad" ...........would this cause the problem?

How to check the eeprom?

[nadeem]

Re: 1800FP Green light on but no image on screen

thx sir i am very thank full to all of u