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Post by mastertech on Nov 7, 2015 17:56:12 GMT -5
So in the picture above your last post, the pin with the ?? is now reading 3.2v dc?
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guptau
Junior Member
Posts: 90 
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Post by guptau on Nov 7, 2015 18:10:55 GMT -5
I think the pin order in my picture above is
1 2 3 5 4
So, yes, Vout is 3.2.
For Q7013: pin#1 is 4.9V and no voltage in any other pin when pin#2 of Q7001 is used as ground. |
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Post by mastertech on Nov 7, 2015 18:16:37 GMT -5
Then that is incorrect. Look at the image I posted from the datasheet. If you turn the datasheet image up side down then you get this:
3 2 1
4 5
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guptau
Junior Member
Posts: 90
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Post by guptau on Nov 7, 2015 18:24:31 GMT -5
You are correct and the order is you are showing. In both cases (7001 and 7013) the VIn is about 5V. Vout is 3.2 and Stb is about 5V for Q7001. No vout and stb for Q70013.
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Post by mastertech on Nov 7, 2015 18:41:14 GMT -5
Ok, so far all is normal.
Now on this same board, locate connector P7501A. DMM on DC voltage, negative probe on pin 10 and positive probe on pin 17. Should be 3.3v
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guptau
Junior Member
Posts: 90
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Post by guptau on Nov 7, 2015 19:24:35 GMT -5
Nope. It is - 8.9 mV.
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guptau
Junior Member
Posts: 90
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Post by guptau on Nov 7, 2015 19:35:30 GMT -5
From the service manual, it seems pin 14 and 16 are sending 3.3V and 5V respectively. Other pins seem to be returning signal. Am I no correct?
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guptau
Junior Member
Posts: 90
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Post by guptau on Nov 7, 2015 19:53:19 GMT -5
I am so sorry. pin# 17 is showing 2.295V. I don't know why earlier measurement was off.
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Post by mastertech on Nov 7, 2015 20:07:33 GMT -5
Unfortunately in your assumption, you are assuming that all power has been turned on, which it is not. Until the CPU turns on all supplies the only supply that is active is standby voltage. The fact that I have you testing at that connector is meaning less. You have to be able to look over a couple pages of schematics at the same time in order to determine what is suppose to happen in order to turn on the circuits and supplies. But let me break it down in short version for now to help you understand. The main MPU (Q7022) is what controls turn on detection and application. It must have standby voltage to be operational in order to receive and execute commands. The CPU requires the +3.3vst to be functional which comes from Q7001. You have verified that voltage is at least coming from there. But we have not yet verified that this voltage is at the MPU. Now if you look ahead to the front panel where the standby button is located you can see that when that button is pushed to turn the unit on, the line "KEY 0" is grounded. So the signal for the MPU to turn on is the grounding of the "KEY 0" line. This means that line must be high to begin with. So when you go to the KEY 0 line where is enters the MPU at pin 144 you can see that the line receives 3.3vst through R7156. Now I could of had you test right there but you may not be able to reach there or if you slip with your probe you could cause damage, so i had you test at the "KEY 0" pin 17 of connector P7501A. You claim to have -8.9mv so that appears to be a problem. Now that you understand more of what to look for, what do you think you should do next?  |
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Post by mastertech on Nov 7, 2015 20:10:56 GMT -5
I am so sorry. pin# 17 is showing 2.295V. I don't know why earlier measurement was off. Ah, so I wrote that story prematurely. Well at least you have an explanation of what is going on. So what do you think you should do now? |
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guptau
Junior Member
Posts: 90
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Post by guptau on Nov 7, 2015 20:28:05 GMT -5
Actually the voltage is 3.295. That means if the MPU is not getting the voltage, it could be because of faulty register R7154/R7156. Am I correct?
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Post by mastertech on Nov 7, 2015 20:46:12 GMT -5
No, sorry.
Lets continue and maybe then you will see where we are going.
You have correct voltage on the key 0 line so now we need to see if the voltage drops when you press the on button (standby) on the front panel. So put your probes on those lines again so you are reading the 3.295 voltage and while you are holding them there, press the on button and see is the voltage drops to zero when the button is pressed. It will return to the 3.2 again when you release the button. You can hold the button for a few seconds to be sure it drops before you release it.
Let me know what you get.
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guptau
Junior Member
Posts: 90
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Post by guptau on Nov 7, 2015 20:53:29 GMT -5
Holding the button did not make a difference. The voltage kept constant 3.295. Is the button disconnected?
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Post by mastertech on Nov 7, 2015 21:02:01 GMT -5
Holding the button did not make a difference. The voltage kept constant 3.295. Is the button disconnected? Well that is somewhat good news. Lets try something before continuing. You do not need your meter for this. Just take a piece of jumper wire and just for a second, touch those two connector pins (pin 10 and pin 17). This will simulate a button press. I want to see if it turns on. I am assuming all board and harnesses are still connected? |
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guptau
Junior Member
Posts: 90
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Post by guptau on Nov 7, 2015 21:09:41 GMT -5
It did make noise. Fan started.
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