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Post by Deleted on Dec 4, 2015 13:09:12 GMT -5
Ok what I know is that Q25 is connected to that blue jumper. When I remove that jumper other status leds go burning so Q25 is connected to the status leds. Could it be a driver for the leds? Could it be switched by U54?
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Post by Deleted on Dec 4, 2015 14:13:09 GMT -5
Yes I have to wait for the board to get cold again to measure again but the strange thing is the valleus on those resistors are climbing while I measure. Do they react the same if you reverse the leeds? Throw it in the freezer to cool down faster. No if I reverse I see totally different vallues but also running. I put it in the freezer and it did not boot as usual. Than I removed the blue jumper and it did boot and sync but with the wrong colour space or something. the jumper does something with 10 bit colour depth. But it is clear that this Q25 acts weired. I measured again those resistors connected to Q25 and all over the place every measurement different and running. What kind of transistor is Q25 what kind of package? Where is the base and the collector and the emitor? Next thing will be to check it but I have the idea it is switched to something at start so perhaps connecting collector and emitor would solve this too? I would loose the jumper ability to switch to 10 bit colour depth but that is no problem. I first have to check this one. |
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Post by Deleted on Dec 4, 2015 14:58:55 GMT -5
Q25 seems to be a FET because the board says D (left) S (top) and G (bottom)
I measured
G->D = OL
G->S = OL
D->G = OL
S->G = 1060
Does this confirm bad function?
Also S is grounded does this identify if it is npn or pnp?
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Post by mastertech on Dec 4, 2015 15:19:43 GMT -5
Do they react the same if you reverse the leeds? Throw it in the freezer to cool down faster. No if I reverse I see totally different vallues but also running. I put it in the freezer and it did not boot as usual. Than I removed the blue jumper and it did boot and sync but with the wrong colour space or something. the jumper does something with 10 bit colour depth. But it is clear that this Q25 acts weired. I measured again those resistors connected to Q25 and all over the place every measurement different and running. What kind of transistor is Q25 what kind of package? Where is the base and the collector and the emitor? Next thing will be to check it but I have the idea it is switched to something at start so perhaps connecting collector and emitor would solve this too? I would loose the jumper ability to switch to 10 bit colour depth but that is no problem. I first have to check this one. So you remove the jumper (not move it to the other loaction) and it boots up fine cold? What are you seeing to say the colorspace is wrong? Do you know what the jumper is for? |
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Post by mastertech on Dec 4, 2015 15:21:24 GMT -5
Q25 seems to be a FET because the board says D (left) S (top) and G (bottom) I measured G->D = OL G->S = OL D->G = OL S->G = 1060 Does this confirm bad function? Usually an FET failure it will go full short. Occasionally there could be a switching problem but you have to remove it for that test. Are there any numbers or letters on it? |
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Post by Deleted on Dec 4, 2015 15:26:17 GMT -5
No if I reverse I see totally different vallues but also running. I put it in the freezer and it did not boot as usual. Than I removed the blue jumper and it did boot and sync but with the wrong colour space or something. the jumper does something with 10 bit colour depth. But it is clear that this Q25 acts weired. I measured again those resistors connected to Q25 and all over the place every measurement different and running. What kind of transistor is Q25 what kind of package? Where is the base and the collector and the emitor? Next thing will be to check it but I have the idea it is switched to something at start so perhaps connecting collector and emitor would solve this too? I would loose the jumper ability to switch to 10 bit colour depth but that is no problem. I first have to check this one. So you remove the jumper (not move it to the other loaction) and it boots up fine cold? What are you seeing to say the colorspace is wrong? Do you know what the jumper is for? Yes it boots fine without the jumper. The image is wrong difficult to describe but I looked in the Moome documentation and the second column of status leds showed that it was in either 10bit or 12 bit coulourdepth mode. Normally it is in 8 bit depth. So I see a led in the second column and I see that the image shows strange artefacts in colours and lines across the image. There is no documentation on the jumper only on the status leds. |
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Post by Deleted on Dec 4, 2015 15:46:19 GMT -5
Ok this is what I know.
Pin 4 of U54 connects to the blue jumper. With the jumper in place it connects to the Drain of Q25. The Source of Q25 is connected to ground so if the gate is switched and the jumper connected pin 4 is to ground.
If there is no jumper it seems pin 4 is left floating.
Difficult to find what switches the Gate of Q25.
What could happen if I connect this pin 4 to ground assuming that somehow the Q25 did not switch it to ground properly?
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Post by mastertech on Dec 4, 2015 16:06:19 GMT -5
Images are not clear enough for me to zoom in and follow traces. Does J2 connect to anything installed or is it a test plug?
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Post by Deleted on Dec 4, 2015 16:39:16 GMT -5
Yes Sw2 connects to D of Q25 and the other side to a number of resistors, difficult but the jumper is allways gone.
But what I did was test the board without Q25 and it acted as if the blue jumper was not there. So second led in second column was on en the image was unreadable and vertical bars on it.
Than I tried contacting pin 4 to ground. First time I booted it seemed to do the same thing as when the blue jumper was not connected and the second led on second column was on but the image was somewhat different but still not right.
Than I booted again same situation and all leds except the third on the second column came on and the image did not sync anymore.
Than I figured that the Q25 was discharging the capacitor C167 since it was between the drain and source so I discharged that cap and everything returned to situation 1.
Ok I placed the fet Q25 back as it seems it discharges the cap and resets some other logic.
I put the board in the freezer for several minutes and tried again and it still worked!!
But I am not going to cheer to soon although I have to say I left it pretty long in the freezer....Hmmmmm.
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Post by Deleted on Dec 4, 2015 16:53:23 GMT -5
Yep another 7 minutes in the freezer and still works. Fingers crossed!  |
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Post by mastertech on Dec 4, 2015 18:11:39 GMT -5
Yes Sw2 connects to D of Q25 and the other side to a number of resistors, difficult but the jumper is allways gone. LOL, I was asking if a harness connects to that header plug or if it is an open header during normal use. If it is a open header for normal use then it is possibly a header for flashing that IC. And the jumper may be there to put it in flash mode and then return to normal mode. Just a thought though. |
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Post by Deleted on Dec 5, 2015 0:11:35 GMT -5
Ok I could not find J2 and thought you ment sw2 but now I see it is the bigger row of pins. Could very well be for flashing. Do you think U54 is a microcontroller with some inside flash memory?
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Post by Deleted on Dec 5, 2015 0:40:31 GMT -5
Pic18f..... Seems to be a microcontroller in 44 pins package that has the pins right.
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Post by Deleted on Dec 5, 2015 1:01:51 GMT -5
Ok did one more test as it is pretty cold now. The Moome switches much faster to the right leds now. It seems this is fixed. Resoldering q25 did it.
Very much thanks for putting me into the direction of those resistors close to q25!!!
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Post by Deleted on Dec 12, 2015 19:21:11 GMT -5
There is a very happy folowup to this. The moome works fine since this repair but there was another problem in my set that also got worse with thw winter days. When the radiator in my home produced warmth it looked like the marquee would lose sync. It was again predictable 10 minutes after the heat came the image would start getting scrambled. So I looked at the source device the cable and could not solve it. Than I found only green was scrambled, a sort of severe streaking. I changed green and red neckboards and still green. Chamged moome still same problem. So now I knew it was the mp modified vim. I crossed colours on the vim and it turned out to be on the miniboard modification. Now I started to sweat and was very happy that I had removed the potting. Turns out the ad835 had a bad solder on a place under the miniboard. That bad solder had been there all the time probable under the potting too. So I fixed that and than I was lucky because the picture became better than ever before. I also have a mp modified moome and somehow that one was to dark but now it was not to dark anymore. It seems to have the same bandwidth as the repaired moome but man it has superior blacklevels. I was shocked watching a movie tonight without heat problems. That vim has never been right until now! Iphone 6 quick shot. It looks sharper and some smearing is gone.  |
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