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 GMC-300E+ stuck in bootloop
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Franzerwin

Germany
8 Posts

Posted - 06/18/2016 :  09:55:28  Show Profile  Reply with Quote
Hi,

I have bought a GMC-300E last year. Everything worked fine.
When I tried using it now it seems that its stuck in a boot loop. Display turns on, you hear the boot beep, then after about 3 seconds you hear a lower beep (error beep?) and it shuts down.
On external power it immediately reboots and the same thing happens again. During the two beeps you can hear the geigermullertube doing its job, this seems fine.
I've tried this with and without connected battery and also only with a battery and no external power connected.
In another post I read about sending a FactoryReset command to the device, this didnt work for me.
Any ideas?

thank you :)

Edited by - Franzerwin on 06/18/2016 09:59:03
Reply #1

ZLM

1102 Posts

Posted - 06/21/2016 :  00:11:19  Show Profile  Reply with Quote
Power key S4 shorted to GND.

You may need to open the case and check the power key.
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Reply #2

Franzerwin

Germany
8 Posts

Posted - 06/21/2016 :  11:00:36  Show Profile  Reply with Quote
Hi,
first thank you for your answer. I have checked it, it seems the power key is okay.
I have made a video:

h**p://stuff.clusterfork.net/gmc300eplus.mp4

When you press the key shortly the display turns on and shuts off when you release it. When you press it for a few seconds, it turns on, errorbeeps and turns off.
This is with a battery, on usb power it immediately turns on again after the error beep and starts rebooting.

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Reply #3

ZLM

1102 Posts

Posted - 06/24/2016 :  20:59:24  Show Profile  Reply with Quote
Connect to Data Viewer software, try to send the "FACTORYRESET" command to unit before it reboots.
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Reply #4

Distelzombie

Germany
188 Posts

Posted - 06/25/2016 :  02:54:56  Show Profile  Reply with Quote
He already did

GMC-300E+ V4.20 with sbt-11a alpha tube

My statements are "stuff-a-hobbyist-says" and not in any way professional.
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Reply #5

ZLM

1102 Posts

Posted - 06/25/2016 :  06:59:48  Show Profile  Reply with Quote
First time I see this problem.

I am still thinking the power key (S4) has problem.

try to remove the yellow tape from the S4 key and clean the contacting point.

Before you put back the S4 key, connect the USB power and see if it works.


Press S3 key and see if it can turn on the unit.
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Reply #6

Franzerwin

Germany
8 Posts

Posted - 06/27/2016 :  13:14:06  Show Profile  Reply with Quote
Hi,

I tried that and cleaned s4, it didn't help.

I put up another video:

h**p://stuff.clusterfork.net/gmc300eplus.s4.mp4

I also verified that there is no connection on s4 while it is not pressed.
When pressing S3 during bootup the errorbeep is gone but it still reboots.

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Reply #7

ZLM

1102 Posts

Posted - 06/28/2016 :  11:12:15  Show Profile  Reply with Quote
can you check what is your GMC-300 hardware version? It should be printed on somewhere on the PCB, it include date and the version, like: 20121217 GMC300 V3.3.

I can let you know where to check it. You need a multi-meter for voltage measuring.
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Reply #8

Franzerwin

Germany
8 Posts

Posted - 06/28/2016 :  12:48:38  Show Profile  Reply with Quote
Thank you for your effort.

Multimeter is available, the pcb version is GMC300plus V1.2 2014.07.23
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Reply #9

ZLM

1102 Posts

Posted - 06/30/2016 :  06:30:50  Show Profile  Reply with Quote
check main CPU pin 8, it should be at 5V when key is released after power up.

The pin 8 connect to the button via D7 diode.

When pressing the key, the pin 8 is low (~0V) and goes hi(~5V) after release the key.
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Reply #10

Franzerwin

Germany
8 Posts

Posted - 07/03/2016 :  15:15:15  Show Profile  Reply with Quote
Hi,

is it this one?
h**p://stuff.clusterfork.net/pin8.jpg

Measure against gnd?
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Reply #11

Franzerwin

Germany
8 Posts

Posted - 07/09/2016 :  17:59:35  Show Profile  Reply with Quote
yes? no? :)
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Reply #12

GBG12

Canada
32 Posts

Posted - 07/11/2016 :  19:52:14  Show Profile  Reply with Quote
That would be pin 8 in your photo, yes. Voltage is always with respect to ground unless otherwise stated. It should reliably change as the button is pressed every time, e.g. 10 out of 10 times.
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Reply #13

GBG12

Canada
32 Posts

Posted - 07/11/2016 :  20:00:32  Show Profile  Reply with Quote
Did the FactoryReset work but did not change the behavior, or did the FactoryReset not work at all?
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Reply #14

ZLM

1102 Posts

Posted - 07/12/2016 :  16:46:45  Show Profile  Reply with Quote
As long as you see the "FACTORY RESET, PLEASE WAIT" message for about 1-2 seconds, then the factory reset feature is working.
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Reply #15

Franzerwin

Germany
8 Posts

Posted - 01/06/2017 :  16:22:54  Show Profile  Reply with Quote
Hi,
sorry it's been a while.
I dont see the factory reset message.

PIN8 is at 5V (high). When pressed it goes to 0V (low). When released it is still low (about 0.5V) till the second beep (the errorbeep) comes. After that the device is turned off and the pin is high again (5V).

btw:
For testing I have connected some pins to the UART. I also power the device through UART right now. In this setup the display is on and charges the battery, not like with usb where its stuck in a poweron/poweroff loop. I cannot see data via UART aswell, tried 9600 and 115200.

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Reply #16

ZLM

1102 Posts

Posted - 01/06/2017 :  22:03:17  Show Profile  Reply with Quote
For the GMC-300E, the UART baud rate is 57600.
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Reply #17

Franzerwin

Germany
8 Posts

Posted - 01/10/2017 :  00:05:23  Show Profile  Reply with Quote
quote:
Originally posted by ZLM

For the GMC-300E, the UART baud rate is 57600.



Thanks, I've tried that, nothing. Tried on two different serialports which normally work. Also reversed rx/tx for testing purposes. It seems its damaged.

Any idea on the low (0.5V) state on pin8 during turnon ?
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Reply #18

ZLM

1102 Posts

Posted - 01/11/2017 :  20:58:09  Show Profile  Reply with Quote
You can write to support@gqelectronicsllc.com for more help.
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