Monochron kit LCD not working

by dzjay on Sun Sep 09, 2012 5:25 pm

Hello,

I just got around to building my Monochron kit I got 2 years ago.

I am a computer programmer, and rather smart in many things, but I am an absolute n00b at electronics.

I followed all directions, and every test succeeded, until I hooked up the LCD. The LCD screen shows nothing. It receives power, for I can see a dim blue glow on the edges, but the screen is dark. I turn the trim knob as indictated, but it makes no difference.

A few things to note:

When cutting the "male header," I accidentally cut into the edged of the female header plastic casing, causing the last pin to become loose. I managed to sit it in place while I soldered the female header to the PCB, and everything seems correct, except that last pin appears "expose").

Can you help me troubleshoot the PCB work or the LCD part in order to solve this problem?

Thank you,
dZ.
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Re: Monochron kit LCD not working

by adafruit_support_bill on Mon Sep 10, 2012 5:25 am

Let's start by getting some clear photos of the front & back of the boards. Maybe a close-up of the suspect header pin too. If there is a problem with pin 1, that is the ground pin for everything but the backlight.
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Re: Monochron kit LCD not working

by dzjay on Mon Sep 10, 2012 6:09 am

adafruit_support wrote:Let's start by getting some clear photos of the front & back of the boards. Maybe a close-up of the suspect header pin too. If there is a problem with pin 1, that is the ground pin for everything but the backlight.


Thank you for the response. I have some photos ready for just such request, see attached. By the silkscreen markings on the PCB, I believe it is indeed pin 1 that is exposed.

The soldering work is not really that good, but the PWR, LED, and SPK tests all resulted as expected.

pin 1 closeup.png
Pin 1 - Close up
pin 1 closeup.png (927.2 KiB) Viewed 1952 times

pcb back.jpg
PCB - Back
pcb back.jpg (325.49 KiB) Viewed 1952 times

pcb front.jpg
PCB - Front
pcb front.jpg (383.11 KiB) Viewed 1952 times


Please let me know if you need more details or better pictures.

Thank you,
-dZ.
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Re: Monochron kit LCD not working

by adafruit_support_bill on Mon Sep 10, 2012 7:07 am

One leg of Q1 looks a bit solder-starved and pin 1 of IC3 is balled up around the pin. If you passed the 'beep' test, then they are probably functional joints, but may develop problems in the future. See the last page of the soldering tutorial for recommendations.http://learn.adafruit.com/adafruit-guide-excellent-soldering

If you have a multimeter, check the continuity between ground on the LCD and ground on the main board. Don't probe on or around Pin 1. Probing an intermittent connection often just makes it conductive and gives misleading results.
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Re: Monochron kit LCD not working

by dzjay on Mon Sep 10, 2012 7:23 am

adafruit_support wrote:One leg of Q1 looks a bit solder-starved and pin 1 of IC3 is balled up around the pin. If you passed the 'beep' test, then they are probably functional joints, but may develop problems in the future. See the last page of the soldering tutorial for recommendations.http://learn.adafruit.com/adafruit-guide-excellent-soldering

If you have a multimeter, check the continuity between ground on the LCD and ground on the main board. Don't probe on or around Pin 1. Probing an intermittent connection often just makes it conductive and gives misleading results.


Pardon my ignorance, but how do I check the ground continuity between the boards, as you suggest? I do not see any pin or contact clearly marked as "ground."

By the way, it did pass the "beep" test, but I take your point, and will try to fix the soldering.

Thank you,
-dZ.
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Re: Monochron kit LCD not working

by adafruit_support_bill on Mon Sep 10, 2012 9:28 am

how do I check the ground continuity between the boards, as you suggest? I do not see any pin or contact clearly marked as "ground."

On the main board, the pin on the side of the DC barrel jack is a reliable ground. On the display, you can follow the trace from pin 1 to some other location with an exposed pad that you can probe. In general, most boards have a large 'ground plane' covering unused areas of the board that all the ground signals connect to.
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Re: Monochron kit LCD not working

by dzjay on Mon Sep 10, 2012 5:04 pm

adafruit_support wrote:
how do I check the ground continuity between the boards, as you suggest? I do not see any pin or contact clearly marked as "ground."

On the main board, the pin on the side of the DC barrel jack is a reliable ground. On the display, you can follow the trace from pin 1 to some other location with an exposed pad that you can probe. In general, most boards have a large 'ground plane' covering unused areas of the board that all the ground signals connect to.


Thanks for that. It is rather hard to trace pin 1, for the LCD component obscures most of the board.

Following the instructions found here for testing continuity, this is what I did:
- I Set my analog multimeter to the Ohms function at x1K scale.
- I Calibrated the meter by ensuring the needle goes to zero (from infinity) when touching both probes.
- With the kit unplugged from the power source, I touched one probe (black) to the pin on the side of the DC barrel jack, and the other (red) to the solder point of pin one on the male connector on the LCD board.
- I also touched the red probe on the exposed part of pin 1 itself.


Both of these tests suggests a closed circuit, for the needle jumped to zero in both cases.

Should this not been an accurate test, kindly suggest which point on the boards I should probe. I apologize for my lack of experience and all the questions, but please understand that I am a novice, and I haven't done any electronics projects in about 20 years.

Thank you,
-dZ.

EDIT: I just realized that you suggested not to test on or around pin 1. I have tested other points that I believe trace back to pin one on the LCD board, including one of the large soldering points of the LCD component itself (on the edge). These suggest also a closed circuit.
Last edited by dzjay on Mon Sep 10, 2012 6:09 pm, edited 1 time in total.
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Re: Monochron kit LCD not working

by adafruit_support_bill on Mon Sep 10, 2012 5:45 pm

That is probably OK. Ideally it would be good to find a ground point away from the suspect connection because pressing on it may make an intermittent joint conductive.

Are you still getting a beep on power-up?
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Re: Monochron kit LCD not working

by dzjay on Mon Sep 10, 2012 6:12 pm

adafruit_support wrote:That is probably OK. Ideally it would be good to find a ground point away from the suspect connection because pressing on it may make an intermittent joint conductive.

Are you still getting a beep on power-up?


Yes, a single "beep," and the LED lights up as well, when flipping the switch.

By the way, I was updating the previous post to say that I tested e continuity at additional spot, and they seem to coincide.
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Re: Monochron kit LCD not working

by adafruit_support_bill on Mon Sep 10, 2012 7:20 pm

Alright. So pin-1 seems to be a solid contact in spite of the clipped housing. The processor is running. Other than the crystal & RTC joints previously mentioned, the solder on the main board looks OK.

Touch up those questionable joints and post a photo showing the full-length of the display header.
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Re: Monochron kit LCD not working

by dzjay on Tue Sep 11, 2012 6:20 am

adafruit_support wrote:Alright. So pin-1 seems to be a solid contact in spite of the clipped housing. The processor is running. Other than the crystal & RTC joints previously mentioned, the solder on the main board looks OK.

Touch up those questionable joints and post a photo showing the full-length of the display header.


Cool. I'll work on fixing the soldering later tonight. In the meantime, I went ahead and double- and triple-checked the instructions to make sure I followed them properly. Everything seems correct.

However, I do have two pieces left over, and I don't see them mentioned in the instructions. The "ISP" gets a mention, but only to warn me not to solder it... (?), then it seems to be forgotten. The other mystery piece, looks rather fancy and complex, but is not even in the list of materials.

I've attached pictures as you requested, along with photos of these last two left-over pieces. I am assuming that by "display header" you mean the multi-pin strip connector on the display board. Please advise.

Thank you,
-dZ.

Display header - top.jpg
Display Header - Top
Display header - top.jpg (284.65 KiB) Viewed 1894 times

Display header - bottom.jpg
Display Header - Bottom
Display header - bottom.jpg (459.75 KiB) Viewed 1894 times

Extra parts.jpg
Spare Parts?
Extra parts.jpg (332.18 KiB) Viewed 1894 times
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Re: Monochron kit LCD not working

by adafruit_support_bill on Tue Sep 11, 2012 6:42 am

Header soldering looks pretty good. Maybe a touch more solder on pin 7 and re-flow 18 and 19. The ISP connector is used later if you want to re-program the clock using an AVR programmer. The other piece is an FTDI Friend. That is another (somewhat easier) method for re-programming the clock. Both are described here: http://www.ladyada.net/make/monochron/bootload.html

The FTDI friend is not part of the Monochron kit. Did you order that separately?
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Re: Monochron kit LCD not working

by dzjay on Tue Sep 11, 2012 6:54 am

adafruit_support wrote:Header soldering looks pretty good. Maybe a touch more solder on pin 7 and re-flow 18 and 19. The ISP connector is used later if you want to re-program the clock using an AVR programmer. The other piece is an FTDI Friend. That is another (somewhat easier) method for re-programming the clock. Both are described here: http://www.ladyada.net/make/monochron/bootload.html


Cool. I'll work on those touch-up points tonight as well.

adafruit_support wrote:The FTDI friend is not part of the Monochron kit. Did you order that separately?


It was a present from my wife, she ordered the kit sometime in 2010. She says she is rather sure she did not make any special or extra order. (Although, to be honest, it's been almost 2 years, and I can't be really sure I hinted to her to get me any additional accouterments.)

I'll be willing to return it if necessary. :)

-dZ.
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Re: Monochron kit LCD not working

by adafruit_support_bill on Tue Sep 11, 2012 7:50 am

I'll be willing to return it if necessary.

No need. Just thank your wife for the nice gift. :wink:
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Re: Monochron kit LCD not working

by dzjay on Sun Sep 16, 2012 2:33 pm

Alright, sorry for the delay, I know how you are at the edge of your seat waiting for me to respond. :)

I went ahead and fixed the joints as you suggested (after reading the guide that you recommended):
- Added more solder to leg of Q1 (though it kept going through the whole to the other side!);
- Reflowed and removed some of the solder on pin 1 of IC3;
- Added more solder to pin 7 of header;
- Reflowed pins 18 and 19 of header;
- and I thanked my wife accordingly for the very nice gift.

Attached are some pictures of the re-touched boards.

I plugged in the power unit and still no dice. I hear a single beep on power-up, and the LED turns on and off with the switch. As before, the LCD screen flashes briefly before going dark again. I can see light emanating from the sides and bottom, so it is getting power, I just don't see any image, no matter how I turn the trim dial.

So, no change. Is there anything else we can try?

-dZ.

IMG_0511.jpg
LCD Header
IMG_0511.jpg (260.21 KiB) Viewed 1834 times

IMG_0510.jpg
Main board
IMG_0510.jpg (416.09 KiB) Viewed 1834 times
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