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Old 6th June 2014, 11:29 AM   #61
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Quote:
Originally Posted by srinath View Post
I bought one that says M168_v2.20. It worked great for a month.
Then I get a 6.3v battery and it goes dead, and that is with a new battery. Ebay seller isn't interested in hearing about it.
Now right from day 1, it never said "bad component" when testing bad components. It would read 1-2 as a capacitor 1.2 pF etc, and ignore the 3rd, when I have a bad transistor clipped across all 3 pins.

What could be the issue ?

Thanks.
Srinath.
If you have connected a battery or charged capacitor to the test pins, your ATmega is probably damaged. The suppply battery voltage is monitored by the tester and a voltage of below 6.4V is set as poor battery level by default. The tester should never report a capacity value of below 25 pF without a parallel diode.
If the tester reports capacity values without a connected component, the calibration process is probably executed wrong.
For calibration the three test pins should be connected together. After starting the tester, the message "Selftest mode ... ?" should be displayed. This message must be acknowledged withing 2 seconds with a key press. The three test pins must be isolated immediately after the "R0=....." message. You must connect a high quality capacitor with a capacity value of more than 100nF to the test pins 1 and 3 after the "C0=..." measurement is done and the "1-||-3 >100nF" message appear. With this step the selftest/calibration is finished.
If your tester don't start the "Selftest mode", your board has an error.
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Old 6th June 2014, 01:37 PM   #62
srinath is offline srinath  United States
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Shorting the 3 pins and pressing test, still says Batt 6.3v empty !.

I guess I get a new atmega ? Or a whole unit.
I better label it and never use it to test a cap. The cap I tested was likely in circuit and likely an accident. I tested many a transistor in circuit. Obviously if the legs had a cap on on the board its like connecting to the cap. So I better not do that ...

So in circuit use of this is out I guess.

Cool.
Srinath.
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Old 6th June 2014, 02:04 PM   #63
srinath is offline srinath  United States
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The chip is a Atmega 328. Now I can read it since I pulled the display out.

Is that what you meant linuxguru ?

If I buy a atmega 328 chip to replace it do I need to program that chip ? Or is it ready to drop into the board.

Thanks.
Srinath.
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Old 6th June 2014, 03:00 PM   #64
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Default eBay listing

Hi, this sounds like a must have, is there one on eBay now? I've looked but there are a few different makes any idea which is the best?
SC
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Old 6th June 2014, 03:41 PM   #65
srinath is offline srinath  United States
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My decision a few months ago was narrowed down by the fact that 80% of them did not have a case. It cant look like a bunch of circuit boards connected by some wires. If I cant operate and make sense of it 3 drinks and a joint or 2 in, its not to be bought.

Yea yea ... I only have a small burn on my finger about 3 yrs ago and I got that sober ... so I know to wear pants when using a soldering iron.

Cool.
Srinath.
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Old 6th June 2014, 05:21 PM   #66
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Quote:
Originally Posted by srinath View Post
If I buy a atmega 328 chip to replace it do I need to program that chip ? Or is it ready to drop into the board.
You need to program it, of course. The images are available at various forums/websites, or you can even rebuild the binary from the source (it's an open-source project).
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Old 6th June 2014, 05:23 PM   #67
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Quote:
Originally Posted by Santa Claws View Post
Hi, this sounds like a must have, is there one on eBay now? I've looked but there are a few different makes any idea which is the best?
Search for the M328 one, with a green ZIF socket and solid brass spacers between the board and display. That one is the most durable, and can be modded if required.
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Old 6th June 2014, 05:57 PM   #68
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Default thanks!

Thanks for that, much appreciated!
SC
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Old 6th June 2014, 07:33 PM   #69
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Quote:
Originally Posted by srinath View Post
Shorting the 3 pins and pressing test, still says Batt 6.3v empty !.

Srinath.
Are you shure, that the battery voltage has a correct 9V level?
Probably you can test with another source to supply the unit.
If the real input voltage is much higher than 6.3V, you can also check the voltage divider build with a 10k / 3.3k resistor divider.
The 10k is connected to the voltage regulator input with one side, the other side is connected to the 3.3k resistor and PC5 of the ATmega. The other side of the 3.3k resistor is connected to GND of course. Another way to avoid the "Batt 6.3V empty!" message is to program the chip with reduced battery empty level (BAT_POOR=5900 for example).

The "in circuit" measurement of DISCHARCHED capacitors can be done with a special function, which can be selected with a menu function "C+ESR@TP1:3" of software version 1.10k for a ATmega328. The capacitor must be connected to TP1 and TP3 and must have at least 2F capacity. You should not expect a good capacity measurement accuracy for this type of measurement because the measurement voltage is very low. Other measurements are not recommended to do "in circuit".
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Old 6th June 2014, 08:46 PM   #70
srinath is offline srinath  United States
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The battery when I hit the start button measures 8.9v or so on my DMM. I even tried with new batteries, same thing.

I dont know how to program it. But the test 10k/3.3k I could try but I dont know what is the voltage regulator in that circuit. I suspect the voltage regulator is what has gone on this. A bad chip will give you nothing. The display is still controlled by the atmega chip, and that is telling it whatever it shows. That to me is indication of something in the atmega working.

Let me try the resistor trick - I may ask more questions ... but I have enough to start soldering away.

Thanks.
Srinath.
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