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jgrice53
Joined: 10 Dec 2014
Posts: 165
Location: marion, sc 29571
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| Posted: Mon Dec 15, 2014 11:34 pm Post subject: |
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that will not be a problem since i had already remove the cpu board and I have not put the screws back in yet.
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jgrice53
Joined: 10 Dec 2014
Posts: 165
Location: marion, sc 29571
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| Posted: Tue Dec 16, 2014 3:45 pm Post subject: |
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okay finally got them tested mac. dmm on diode, .678 emitter to base, ol base to emitter, .678 base or emitter to collector and ol from collector to emitter or base.
1k on r248 r249
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Dec 16, 2014 5:28 pm Post subject: |
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Ok, let me bring you up to speed as to where we are at.
You were getting an over heat error so I had you test for voltage on resistors R295 and R264. These are the 2 protect lines to the CPU for over temp. Your readings of 3.2v at all 4 points were correct so it was not an actual over temp triggering the problem.
I then had you test R263 which is the protect line for overload and DC detect. Your reading of 3.2v on both sides were correct so no problem there.
Next I had you try a master reset in case it was a firmware glitch causing the error. That appeared to clear the over heat error but not the shutdown.
So now I had to look at all the pins on the CPU to see what other detect circuits there were. Since it does power up and then shuts down it would most likely be a protect detection causing the problem.
So I see there is a power supply detection circuit in case part of the supply goes down.
So I next had you test pin 19 of the CPU which is the power down line. Your 0v was incorrect. Should be 3.2v also. I then had you test pin 12 of the connector since this is the incoming line from the power supply. Should be zero volts and that is what you had. So it was not a problem on the power supply since it was sending the correct voltage. So something is going on on the CPU board causing the 0v on pin 19.
Shorted Q203 or open R248 or r249 would cause this. You had to test with no power and your tests appear to be fine. But there are a few other components there that could be causing the problem.
So, the question is, is there something pulling that line down or is the the CPU itself pulling it down. Naturally the latter is not good. But we need to verify.
So to verify, it needs to be powered on to test. And since you cannot reach R248 with the board in then you will have to solder a wire to each side of it so you can test off those wires with it installed and powered up. Just use the smallest wire you can find. I use insulated magnet wire which is super thin. Let me know your readings.
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jgrice53
Joined: 10 Dec 2014
Posts: 165
Location: marion, sc 29571
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| Posted: Wed Dec 17, 2014 4:42 am Post subject: |
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Okay it took a little doing but i managed to get the wires soldered to R248 and installed the board and plugged it in and it had .5v... pressing the power button made no change still read .5v
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Wed Dec 17, 2014 5:02 am Post subject: |
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| jgrice53 wrote: | | Okay it took a little doing but i managed to get the wires soldered to R248 and installed the board and plugged it in and it had .5v... pressing the power button made no change still read .5v |
.5v on both wires? Are you grounding your neg probe and testing each wire with your pos probe?
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jgrice53
Joined: 10 Dec 2014
Posts: 165
Location: marion, sc 29571
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| Posted: Wed Dec 17, 2014 5:24 am Post subject: |
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oops....3.25v and 2.76v
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Wed Dec 17, 2014 5:44 am Post subject: |
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That's better. Those are correct voltages. However it is not good news.
This will be you last tests. I am going off for tonight so I will check your results tomorrow.
Turn it back on and reverify those 2 voltages. If they are still the same i want you to test pin 19 on the CPU again and see if it is still 0v. If it is then turn it off, pull out the board again, locate R259 and remove it. Put board back in and test pin 19 again along with the 2 wires and give me the results.
If it is a surface mount resistor use 2 soldering irons to remove it. If you only have 1 iron then don't worry if you damage the resistor. It is a last ditch test anyways.
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jgrice53
Joined: 10 Dec 2014
Posts: 165
Location: marion, sc 29571
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| Posted: Wed Dec 17, 2014 5:48 am Post subject: |
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okay, i will get on it tomorrow morning mac
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jgrice53
Joined: 10 Dec 2014
Posts: 165
Location: marion, sc 29571
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| Posted: Wed Dec 17, 2014 2:32 pm Post subject: |
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good morning mac. I checked pin 19 again and now i am getting 2.7v, so I did not remove R259
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Wed Dec 17, 2014 3:07 pm Post subject: |
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Does it turn on?
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jgrice53
Joined: 10 Dec 2014
Posts: 165
Location: marion, sc 29571
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| Posted: Wed Dec 17, 2014 3:18 pm Post subject: |
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turns on for 3sec display shows vol min then shuts off
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Wed Dec 17, 2014 4:08 pm Post subject: |
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Do you think you had the 2.7v on pin 19 before and just didn't get a good test on it?
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jgrice53
Joined: 10 Dec 2014
Posts: 165
Location: marion, sc 29571
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| Posted: Wed Dec 17, 2014 4:21 pm Post subject: |
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yes i think that is very possible. I noticed that when i checked it this time, it would read 0v and then as i moved the tip of the probe it would fluctuate. so i became suspicious of the probe tip not making good contact," i was being very careful not to short the pins". I attach a needle with an alligator clip to the probe and there was the 2.7v
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Wed Dec 17, 2014 5:35 pm Post subject: |
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At this point I think we need to check all the supply voltages. You will need to jump the main relay first. Go to the power supply board and locate the main relay (RLY301). Next to it is C304. Solder a wire across both legs of C304. Let me know when you have this done and I will give you the next test points.
Last edited by macgyver655 on Wed Dec 17, 2014 8:20 pm; edited 1 time in total
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jgrice53
Joined: 10 Dec 2014
Posts: 165
Location: marion, sc 29571
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| Posted: Wed Dec 17, 2014 6:40 pm Post subject: |
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CP301 is the A/C plug correct? do you want me to disconnect the plug and solder a wire across the 2 pins of CP301?
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Wed Dec 17, 2014 8:21 pm Post subject: |
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| jgrice53 wrote: | | CP301 is the A/C plug correct? do you want me to disconnect the plug and solder a wire across the 2 pins of CP301? |
Oooops! No, that was a mistake. I corrected that post so go back and check it. Good catch.
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jgrice53
Joined: 10 Dec 2014
Posts: 165
Location: marion, sc 29571
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| Posted: Wed Dec 17, 2014 8:49 pm Post subject: |
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okay, i got it now. jumper wire across C304, done.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Wed Dec 17, 2014 9:50 pm Post subject: |
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I need a picture of the receiver looking straight down from the top.
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jgrice53
Joined: 10 Dec 2014
Posts: 165
Location: marion, sc 29571
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| Posted: Wed Dec 17, 2014 11:32 pm Post subject: |
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I am having trouble reducing the size of the picture so it will upload. it is over 3meg. max size is 750kb
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jgrice53
Joined: 10 Dec 2014
Posts: 165
Location: marion, sc 29571
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| Posted: Wed Dec 17, 2014 11:33 pm Post subject: |
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i know i have done it with the other pictures, but i can't seem to do it again
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