how can I know if my mac is truly communicating with the MD?

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Re: how can I know if my mac is truly communicating with the MD?

Postby dmitri » Thu Feb 05, 2009 10:22 pm

jeffbeckib wrote:When I short pin 1 and 3 on lcd I get a row of white blocks on the bottom row.

Are you sure you held the LEFT key when you were powering up? To be absolutely sure, power it up again holding the key pressed and measure voltage on pin 8 of Atmega while still holding the key pressed. Is it 0V? If it's more than 0.5V-1V, stop there and report.

If it is 0V then go on and measure all the resistances I advised you to do. Don't forget to switch off/disconnect from USB.
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Re: how can I know if my mac is truly communicating with the MD?

Postby jeffbeckib » Thu Feb 05, 2009 10:34 pm

with the meter back on DC 20V I was getting a reading of 5V on pin 8 of the atmega while still holding the left button, I was still getting a reading of 5V after eventually letting go of the button.
I've tried measuring the resisters, but I'm getting no reading on any of them. The numbers start to climb and then go to 0, pin 4 is the ground on the usb. the meter is set to 2000 ohms.



dmitri wrote:
jeffbeckib wrote:When I short pin 1 and 3 on lcd I get a row of white blocks on the bottom row.

Are you sure you held the LEFT key when you were powering up? To be absolutely sure, power it up again holding the key pressed and measure voltage on pin 8 of Atmega while still holding the key pressed. Is it 0V? If it's more than 0.5V-1V, stop there and report.

If it is 0V then go on and measure all the resistances I advised you to do. Don't forget to switch off/disconnect from USB.
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Re: how can I know if my mac is truly communicating with the MD?

Postby dmitri » Thu Feb 05, 2009 10:45 pm

jeffbeckib wrote:with the meter back on DC 20V I was getting a reading of 5V on pin 8 of the atmega while still holding the left button, I was still getting a reading of 5V after eventually letting go of the button.

I said you to stop right there.
When you press this button you are effectively connecting pin 8 of Atmega to the ground thus pin 8 must read 0V.
Disconnect the buttons from the board. Measure resistance of the button LEFT when you press it and when you release it. Measure on 2000 Ohm range.
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Re: how can I know if my mac is truly communicating with the MD?

Postby jeffbeckib » Thu Feb 05, 2009 11:10 pm

ok, you'll need to explain things to me like I'm a 2 year old. I tried measuring resistance on the buttons, but the values are all over the place. They are Zero, then when I push the button they jump around from one 3 digit number to another, most of the time it seems to be incremental.

I hold the left button, while holding it I turn on the unit and measure pin 8 of the atmega and I get 0V, but it's not easy holding the black ground on the meter to the ground on the board, hold the button in, turn on the power switch of the MD all at the same time. but I think I did it right



dmitri wrote:
jeffbeckib wrote:with the meter back on DC 20V I was getting a reading of 5V on pin 8 of the atmega while still holding the left button, I was still getting a reading of 5V after eventually letting go of the button.

I said you to stop right there.
When you press this button you are effectively connecting pin 8 of Atmega to the ground thus pin 8 must read 0V.
Disconnect the buttons from the board. Measure resistance of the button LEFT when you press it and when you release it. Measure on 2000 Ohm range.
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Re: how can I know if my mac is truly communicating with the MD?

Postby jeffbeckib » Thu Feb 05, 2009 11:26 pm

I just noticed this, while scraping away a small piece of solder that was making a resistor and pin 28 on the atmega32 touch, I must have exposed the coper clad under the board. Does this look like it could be a problem? any way I can test to see if the two are actually making contact together? and if so, can I do anything to repair this problem?
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Re: how can I know if my mac is truly communicating with the MD?

Postby dmitri » Thu Feb 05, 2009 11:36 pm

jeffbeckib wrote:ok, you'll need to explain things to me like I'm a 2 year old.

Do you think it is fun to explain to 'a 2 year old' how to test electronics?

I tried measuring resistance on the buttons, but the values are all over the place. They are Zero, then when I push the button they jump around from one 3 digit number to another, most of the time it seems to be incremental.

Find on the dial a position with a diode sign. It's a position on the bottom of the dial and slightly to the right. Switch to it. Now when you connect probes to each other the meter should make a sound meaning there is a 0 resistance between the probes. Now test the LEFT button when it is pressed and when it is released.

I hold the left button, while holding it I turn on the unit and measure pin 8 of the atmega and I get 0V, but it's not easy holding the black ground on the meter to the ground on the board, hold the button in, turn on the power switch of the MD all at the same time. but I think I did it right

So where you were telling the right reading? Here, where you say it is 0V, or some posts above, where you say it is 5V?

I'm starting to feel (actually I have been feeling for some time) that you need to find a friend with more electronics knowledge than you have to help you to find the problem. It really looks like I'm trying to help a toddler to fix a supercomputer.
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Re: how can I know if my mac is truly communicating with the MD?

Postby dmitri » Thu Feb 05, 2009 11:40 pm

jeffbeckib wrote:I just noticed this, while scraping away a small piece of solder that was making a resistor and pin 28 on the atmega32 touch, I must have exposed the coper clad under the board. Does this look like it could be a problem? any way I can test to see if the two are actually making contact together? and if so, can I do anything to repair this problem?

pin 28 IS connected to a resistor. See the schematic. Or are you talking about some other resistor?
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Re: how can I know if my mac is truly communicating with the MD?

Postby jeffbeckib » Thu Feb 05, 2009 11:45 pm

The diode test works fine, I get a beep when the button is pressed and I've also discovered that the new button I got from radio shack wasn't a momentary button, but a toggle, so when I push it, the beep is constant until I push it again....

I'm very good with following instructions, but it's just that you're assuming I understand many of the basics.
BTW the pic icu has been removed durring all this testing.
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Re: how can I know if my mac is truly communicating with the MD?

Postby jeffbeckib » Thu Feb 05, 2009 11:49 pm

Is it connected to the risister right next to pin 28?? If you look at my image, I'm referring to the resister right next to pin 28



dmitri wrote:
jeffbeckib wrote:I just noticed this, while scraping away a small piece of solder that was making a resistor and pin 28 on the atmega32 touch, I must have exposed the coper clad under the board. Does this look like it could be a problem? any way I can test to see if the two are actually making contact together? and if so, can I do anything to repair this problem?

pin 28 IS connected to a resistor. See the schematic. Or are you talking about some other resistor?
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Re: how can I know if my mac is truly communicating with the MD?

Postby dmitri » Thu Feb 05, 2009 11:56 pm

Replace the button.
Then do all the tests again including viewtopic.php?p=6208#p6208 and come back again tomorrow with your results.

Is it connected to the risister right next to pin 28?? If you look at my image, I'm referring to the resister right next to pin 28

I cannot understand what resistor you're talking about. pin 28 must be connected to one and only resistor.
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