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Forum Index : Microcontroller and PC projects : Maximite power-up fault
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| Ben Baker Newbie  Joined: 19/11/2011 Location: AustraliaPosts: 4 |
Hi guys. I put together the Altronics Maximite kit and have a problem. At power-up, the power LED sometimes starts flashing at about 2kHz, with nothing on the VGA screen. The output is set for VGA only,and I am using an LCD screen. I have carefully checked all component values and placement, especially the three tantalums, and the voltages at the input and output of the regulators are as to be expected. It seems that the device is sometimes going into 'partial'bootloader mode without sw2 being pressed,although pressing sw2 produces a more solid and reliable flash rate as the instructions suggest. There is continual continuity from the cathode of the power LED through sw2 which seems to indicate a faulty sw2. Has anyone experienced a similar problem? Any suggestions would be welcome - I dread the thought of removing sw2, particularly if it turns out to be unnecessary. Ben Baker. |
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sparkey Senior Member  Joined: 15/06/2011 Location: AustraliaPosts: 819 |
have you got the little square switch in at the wrong way around as if this is not correct you could be shorting it into boot "load"mode ..remove sw 2 and see what happens then.... technicians do it with least resistance |
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bigmik Guru  Joined: 20/06/2011 Location: AustraliaPosts: 2914 |
Gday Ben, Not having a `real' mximite in my posession I am just theorising, but those little square switches that are uses for SW2 need to be inserted the correct way.. I would guess that the switch has been inserted 90 degress rotated which would mean the switch is permanently `on' so you would enter boot mode. And of course have no VGA output. Pull the switch out and see if the VGA springs to life.. if so then it is either faulty or rotated 90degrees. Regards, Mick Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<< |
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| bigmik Guru Joined: 20/06/2011 Location: AustraliaPosts: 2914 |
As usual beaten to the punch by sparkey... 
Good on yer mate... you answered whilst I was typing.. at least we are both on the same track mick Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<< |
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| sparkey Senior Member Joined: 15/06/2011 Location: AustraliaPosts: 819 |
it happen`s ... i am still having trouble getting the lcd sheild to work on the "mega" have tried several combinations of jumping pins but still cannot get it going it works fine on the cross and an altronics so its not a harwhare issue,,,.... technicians do it with least resistance |
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| sparkey Senior Member Joined: 15/06/2011 Location: AustraliaPosts: 819 |
also check that u dont have the xtal shorted to close to the pcb i cannot rember what fault this produces but it can short to the pcb if you dont leave a mm between it and the board... technicians do it with least resistance |
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| bigmik Guru Joined: 20/06/2011 Location: AustraliaPosts: 2914 |
Hi Sparkey, I have got the LCD working fine on the Duinomite... There are 2 track cuts and 2 jumpers I will try to get photos today for you... problem is the PCBs are BLACK and photos are hard to take Mick Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<< |
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| sparkey Senior Member Joined: 15/06/2011 Location: AustraliaPosts: 819 |
thank you ...sparkey.....hope ben`s having some luck... technicians do it with least resistance |
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| sparkey Senior Member Joined: 15/06/2011 Location: AustraliaPosts: 819 |
ben only one of the pads where the switch is mounted ..is connected to ground if the pad that comes from the chip "think it`s pin 47 on the chip" this should not be grounded if this is the case you may have a board fault or a short to ground as the boot loader is activated by grounding this pin to earth "0 volts".... technicians do it with least resistance |
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| larny Guru Joined: 31/10/2011 Location: AustraliaPosts: 346 |
I mounted my Xtal on a "chair" made from part of the plastic insert that was inside the SD Card socket as supplied in the kit. I cut the best part out with scissors & drilled 2 holes. Here is a photo Len 
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| aargee Senior Member Joined: 21/08/2008 Location: AustraliaPosts: 255 |
I think you meant 2Hz not 2kHz? Your saying it powers up intermittently flashing at 2Hz and other times the Maximite works OK? If the LED starts flashing sometime after power up, you may have a more serious problem than just SW2, as the firmware only looks at SW2 on power up. Pressing it at any other time has no effect. As for SW2, these little switches don't like a *lot* of heat, the plastic membranes warp and distort or even burn(!), leaving a resistance across the switch terminals. Failing the SW2 being faulty, there may have been a problem with the PIC soldering when the board was manufactured as this part of the circuit is pretty simple. - Rob. For crying out loud, all I wanted to do was flash this blasted LED. |
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