new build lcd question


 
G

George Bean

New member
completed the build and all works except the lcd monitor. the monitor has power but only displays two rows of black squares. not sure but i think it might be a solder short between the two boards.

question is should i replace/resolder the lcd or just run through the app? am i missing anything just running with linkmeter and no lcd?
 
Yup more than likely you just need to adjust the potentiometer to adjust the contrast. The blue cube that you soldered on has a small philips (could be flathead) screw that you turn to adjust the contrast.
 
I think if you can see the squares, the contrast is ok. Post some high res pics of the front and back of the board and it might help others see if something is installed wrong.
 
Not to be too critical of your soldering.....but.....
take a look at the soldering job where the LCD is connected to the HM board on this picture (it's not mine).
peY2wUH.jpg


I think it might be a good idea if you go over your 12 solder joints on each side of the board and make sure there's enough solder on them. The example in the picture is a good soldering job.
 
D5, D6, D7 don't look great on the front, D4 & E don't look good on the back.
Flux the pins, heat them up till the solder on there melts, then add a bit. You'll probably get it goin.
 
you can be critical of the soldering, when i first powered on the heatmeter i was surprised the lcd was the only thing that didn't work : )

on the photos i did not have a lot of solder in anticipation of having to remove the lcd and start over. i did add more solder to all lcd pins, still no luck
 
Got a multimeter? Test to make sure you don't have a short between any adjacent pins on the LCD.

Also download this and zoom in on it. You'll see the traces on the board and it can help you test for connectivity between the IC3 chip and the LCD.
 
Are many pins joined or just a few? You should be able to get your soldering iron nice and hot and touch things up without too much trouble.
 
George Bean said:
there is continuity between lcd pins, i think it is solder between the two board where they meet.
Click to expand...

If there is solder behind/between the boards (like the PBJ in a PBJ sandwich) and it's bridging some of the pins/pads, I think you'll have to remove the LCD and clean all that up with some copper braid and make sure there's nothing offending happening between the boards.

But, that's a lot of work. You may want to check continuity between adjacent pins first, to see if you have a short where there shouldn't be.

Or, the LCD could be bad I suppose.

But, I'd expect it's more likely the solder connections we can see that is where the problem is.
 
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George Bean said:
there is continuity between lcd pins, i think it is solder between the two board where they meet.
Click to expand...
Did you apply any solder to that side of the boards before mating or soldering the header? You would have to get 2 adjacent pins really hot & have a pool of solder for it to flow between those pins. Even though it looks like you got some of the LCD pins really hot, unless you blobbed solder on the opposite side of where you should have, I don't see it happening. You would have also likely had bridges on the soldering side as well, which you said you didn't.

You may also want to reflow IC3. Thats what sends data to the LCD & you don't have much solder showing on the component side pads. You want the solder to 'wick' up the leg of the component & connect it to the pad on the opposite side of the board from where you have the iron. You got solder to climb the leg, but not much on the pads. for now, you can heat the component-side pads/legs & just add a bit of solder. DIP components can suck up a surprising amount of heat.

The LCD is powering up & has backlight control. It's just not getting (correct) data. Your pics show some of the 'D' & 'E' pins didn't have enough solder and the shift register (IC3) doesn't have enough solder on the component side. Start there.
 
the first time i put the lcd on backwards, i cleaned both surfaces and reattached with the correct orientation. however, i may not have taken as much time as i should have to correct. please confirm which are the d & e pins?

i am hoping to find time to work on this over the weekend. thanks all for the help, much appreciated.
 
I looked at the pic of the board upclose and can see a few pins that don't have any/enough solder, and some that look like cold solder joints. If I where you, go over the whole board again with your soldering iron and reflow every pin just to be sure.
 
George Bean said:
the first time i put the lcd on backwards, i cleaned both surfaces and reattached with the correct orientation. however, i may not have taken as much time as i should have to correct. please confirm which are the d & e pins?

i am hoping to find time to work on this over the weekend. thanks all for the help, much appreciated.
Click to expand...

When you can see the LCD, look at the labels on the LCD header pins. Power, gnd, E(nable), etc. The 'D' pins are what actually sends the data. Dave circled D7 above. The pins right below that from the DIP shift register are what they connect to. on the opposite side, I think you also need more solder to connect the legs & pads.
 
thanks to all for the help, i think i am just stumped. resoldered on the boards as suggested then removed an replaced the lcd. the new lcd shows the top row of squares only. everything else seems to work- probes and the linkmeter app. i may just run without the lcd.
 
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