Topics

Test - Not working


Patrick
 

So the board is built and I thought I'd hook it up and just see if I get anything on the display and I'm getting nothing.
Input is 14v, I do see 5v on the side of the voltage regulator.
Even though I have disconnected the circuit for 5v via USB I am still able to program the teensy
on the display I'm seeing the following for voltage..

The display's pins have labels.

vss
vdd - 5v
vo - 3.1v
rs - 3.3
rw
rs
e
d0 - 5v
d1
d2 - 5v
d3 - 5v
d4
d5
d6
d7
a - 5v
k

Some of the pins are showing mV but if it's a signal a volt meter won't pick that up.

There is no light on the teensy

Any ideas?


Leonard A. Gucciardo KD2NEN
 

Are you getting a backlight?

Leonard A. Gucciardo
KD2NEN

On Feb 7, 2021, at 8:10 AM, Patrick <kd7wpq@...> wrote:

So the board is built and I thought I'd hook it up and just see if I get anything on the display and I'm getting nothing.
Input is 14v, I do see 5v on the side of the voltage regulator.
Even though I have disconnected the circuit for 5v via USB I am still able to program the teensy
on the display I'm seeing the following for voltage..

The display's pins have labels.

vss
vdd - 5v
vo - 3.1v
rs - 3.3
rw
rs
e
d0 - 5v
d1
d2 - 5v
d3 - 5v
d4
d5
d6
d7
a - 5v
k

Some of the pins are showing mV but if it's a signal a volt meter won't pick that up.

There is no light on the teensy

Any ideas?

--
LennyG KD2NEN


Leonard A. Gucciardo KD2NEN
 

If you are not getting a backlight on the display you have it hooked up in reverse. If you are getting a backlight adjust the potentiometer until you get a display. Send me a clear picture of the display connected so I can see if you have it backwards

Leonard A. Gucciardo
KD2NEN

On Feb 7, 2021, at 9:14 AM, Leonard A. Gucciardo KD2NEN via groups.io <lgucciar@...> wrote:

Are you getting a backlight?

Leonard A. Gucciardo
KD2NEN

On Feb 7, 2021, at 8:10 AM, Patrick <kd7wpq@...> wrote:

So the board is built and I thought I'd hook it up and just see if I get anything on the display and I'm getting nothing.
Input is 14v, I do see 5v on the side of the voltage regulator.
Even though I have disconnected the circuit for 5v via USB I am still able to program the teensy
on the display I'm seeing the following for voltage..

The display's pins have labels.

vss
vdd - 5v
vo - 3.1v
rs - 3.3
rw
rs
e
d0 - 5v
d1
d2 - 5v
d3 - 5v
d4
d5
d6
d7
a - 5v
k

Some of the pins are showing mV but if it's a signal a volt meter won't pick that up.

There is no light on the teensy

Any ideas?

--
LennyG KD2NEN

--
LennyG KD2NEN


Patrick
 
Edited

Okey dokey.
Got the pictures taken and now to answer the questions!
BTW, thank you EVERYONE for being kind and responding!
This is likely one of the few times I've posted in a group and not felt like an idiot for asking questions.

"Are you getting a backlight"; no, there is no response from the display. No backlight and no LCD images or text on the screen. I only know this because I put a flashlight to it thinking that maybe the backlight wasn't working.

"If you are not getting a backlight on the display you have it hooked up in reverse. If you are getting a backlight adjust the potentiometer until you get a display. Send me a clear picture of the display connected so I can see if you have it backwards"
I actually tried connecting the display in both directions, neither worked.

I attached the pictures. You'll see the potentiometer isn't connected but I did try it connected.

I was able to validate 12v to the voltage regulator and 5v out of the regulator so my power polarity is correct.


Leonard A. Gucciardo KD2NEN
 

Ok looking at pictures you have the display connected correctly. Check the voltage between the A and K terminals of the display and see if you are getting about 2.5 volts. That is the led used for back light. Everything looks right so it should be booting up and doing something. You could have a bad ribbon cable not crimped properly. On my boards I use a female connector for the display on one side and a male on the other so I can plug the display into the main board without cables. I can’t tell if that’s how you did it. If you do have a male on one side and a female on the other remove the ribbon cable and plug the 2 together and see if it works. Also make sure all your pins for the Teensy are going into the socket and not bent over. The led on the teensy will no longer light once it is programmed. 

Leonard A. Gucciardo
KD2NEN

On Feb 7, 2021, at 10:30 PM, Patrick <kd7wpq@...> wrote:



[Edited Message Follows]

Okey dokey.
Got the pictures taken and now to answer the questions!
BTW, thank you EVERYONE for being kind and responding!
This is likely one of the few times I've posted in a group and not felt like an idiot for asking questions.

"Are you getting a backlight"; no, there is no response from the display. No backlight and no LCD images or text on the screen. I only know this because I put a flashlight to it thinking that maybe the backlight wasn't working.

"If you are not getting a backlight on the display you have it hooked up in reverse. If you are getting a backlight adjust the potentiometer until you get a display. Send me a clear picture of the display connected so I can see if you have it backwards"
I actually tried connecting the display in both directions, neither worked.

I attached the pictures. You'll see the potentiometer isn't connected but I did try it connected.

I was able to validate 12v to the voltage regulator and 5v out of the regulator so my power polarity is correct.
<0207211913b.jpg>
<0207211912.jpg>
<0207211913.jpg>
<0207211912a.jpg>

--
LennyG KD2NEN


Immo
 

hi Patrick,
following your problems, I looked after the table of voltages, you sent some days ago:
I guess, if you really have 5V at the anode (A) of the backlight. This would be the issue on your wires. The diode is perhaps burnt. sorry for that. 
I have no other idea. sorry.
73, Immo, DL5KB 


On Sun, Feb 7, 2021 at 02:10 PM, Patrick wrote:
The display's pins have labels.

vss
vdd - 5v
vo - 3.1v
rs - 3.3
rw
rs
e
d0 - 5v
d1
d2 - 5v
d3 - 5v
d4
d5
d6
d7
a - 5v
k


Immo
 

Patrick,
another thing: did you mesure the voltages against pin1 (Vss) of the display? If not, hopefully the connection to Vss of the display is interrupted...
let me know.
Immo


Patrick
 

A is 5v, K is about 13mV

As for the cable I used a ribbon cable from my Raspberry Pi kits. It's female on both ends.

On the display I clipped the pins for the device that was on it and un-soldered them one at a time and sucked them out clean with a solder sucker. I then soldered in some of the pins I used for the tuner main board.

It looks as if the voltages I got on the display are the same that I got on the board, so it seems to be connecting.

I do wonder if maybe I blew a diode when I un-soldered them and turned them around when I had them reversed, that is if those are the diodes you are talking about.


Patrick
 

VSS of the display gives me about 8.7mV

Even if the light on the display was burnt I should still be able to see something on the display with a flash light but I'm not.


Patrick
 

OK so here is what I did with no changes (unfortunately)

I replaced the diodes D1 and D5 (just in case). I put a flash light on the display to see if there was any changes in the display and re-programmed the Teensy without any changes.
During programming there was nothing and after programming there is nothing on the display.

I even power cycled it to be sure. No changes.
Turned the optical potentiometer, no changes.

The Teensy I'm using is this one...
https://www.amazon.com/dp/B015QUPO5Y/ref=cm_sw_em_r_mt_dp_PBFW9SZYXG9STZ95674D?_encoding=UTF8&psc=1

I'm not good with electrical components so I'm at a loss as to what to do next.

I am able to a video conference if someone wanted to do something like that to see if someone can help me figure out what's going on.


Leonard A. Gucciardo KD2NEN
 

Patrick you should have 5 volts on vss pin. Check if you have it there to ground.

Leonard A. Gucciardo
KD2NEN

On Feb 8, 2021, at 4:23 PM, Patrick <kd7wpq@...> wrote:



OK so here is what I did with no changes (unfortunately)

I replaced the diodes D1 and D5 (just in case). I put a flash light on the display to see if there was any changes in the display and re-programmed the Teensy without any changes.
During programming there was nothing and after programming there is nothing on the display.

I even power cycled it to be sure. No changes.
Turned the optical potentiometer, no changes.

The Teensy I'm using is this one...
https://www.amazon.com/dp/B015QUPO5Y/ref=cm_sw_em_r_mt_dp_PBFW9SZYXG9STZ95674D?_encoding=UTF8&psc=1

I'm not good with electrical components so I'm at a loss as to what to do next.

I am able to a video conference if someone wanted to do something like that to see if someone can help me figure out what's going on.


--
LennyG KD2NEN


Patrick
 

Pin 1 being VSS does not have 5v, it's about 10mV

Pin 2 being VDD does indeed have 5v

I tried swapping them and nothing.


Patrick
 

And I just saw that second part about the ground.

Pin 1 VSS is indeed grounded
Pin 2 VDD is 5v


Patrick
 

Sorry for all the messages. Just trying to figure this out.

So the little controller that came on my LCD has a LED input and from what I can make of it the ground is pin 2 VSS, the positive seems to run through the board to D7 (4.5K ohms) and K (10K ohms). I could have that backwards too, no way to tell if I can't re-connect and light up the screen.

I'm questioning if this display is even properly designed for this board or if it'll even work with this board, as such maybe I should order a new display.

Can someone point me in the direction of a replacement display that will work properly?

Also, is there another way I can test the board without a display?


Leonard A. Gucciardo KD2NEN
 

I am thinking you have a solder bridge somewhere pulling down your supply. Take a good picture of the bottom of the pc board so I can look it over

Leonard A. Gucciardo
KD2NEN

On Feb 8, 2021, at 9:57 PM, Patrick <kd7wpq@...> wrote:

Sorry for all the messages. Just trying to figure this out.

So the little controller that came on my LCD has a LED input and from what I can make of it the ground is pin 2 VSS, the positive seems to run through the board to D7 (4.5K ohms) and K (10K ohms). I could have that backwards too, no way to tell if I can't re-connect and light up the screen.

I'm questioning if this display is even properly designed for this board or if it'll even work with this board, as such maybe I should order a new display.

Can someone point me in the direction of a replacement display that will work properly?

Also, is there another way I can test the board without a display?

--
LennyG KD2NEN


Leonard A. Gucciardo KD2NEN
 

This is the display I am using and it works fine. LCD 16x4 1604 Character LCD Display Module LCM Blue Blacklight 5V for Arduino https://www.amazon.com/dp/B07ZNNRCLF/ref=cm_sw_r_cp_api_glt_fabc_G93Y5W5Y6P2VXSHA6SVQ

Leonard A. Gucciardo
KD2NEN

On Feb 9, 2021, at 8:29 AM, Leonard A. Gucciardo KD2NEN <lgucciar@...> wrote:

I am thinking you have a solder bridge somewhere pulling down your supply. Take a good picture of the bottom of the pc board so I can look it over

Leonard A. Gucciardo
KD2NEN

On Feb 8, 2021, at 9:57 PM, Patrick <kd7wpq@...> wrote:

Sorry for all the messages. Just trying to figure this out.

So the little controller that came on my LCD has a LED input and from what I can make of it the ground is pin 2 VSS, the positive seems to run through the board to D7 (4.5K ohms) and K (10K ohms). I could have that backwards too, no way to tell if I can't re-connect and light up the screen.

I'm questioning if this display is even properly designed for this board or if it'll even work with this board, as such maybe I should order a new display.

Can someone point me in the direction of a replacement display that will work properly?

Also, is there another way I can test the board without a display?

--
LennyG KD2NEN


Immo
 

On Mon, Feb 8, 2021 at 08:34 PM, Patrick wrote:
VSS of the display gives me about 8.7mV

Even if the light on the display was burnt I should still be able to see something on the display with a flash light but I'm not.
hi Patrick,

the setting of the contrast affects visibility. If not found the right point, you won't see something, even lighted with a torch from above...
But after all, don't waste your time. The backlight-diode is blown and repairing it is a difficult game.
And another thing: you won't see anything also, if you connect the display while the teensy is just running. On start of programm the display is resetted and brouht to a defined start.
Without this, the display sometimes would behave strange...

73, Immo, DL5KB


Patrick
 

Leonard, I'll attach pictures here. I'm pretty sure I don't have a bridge. I was pretty careful to not bridge anything. Granted I'm not the best with soldering as I don't solder a lot.

I did already ordered a LCD but I bookmarked that LCD in case I run into problems again, so thank you for that!

Immo, good to know. I'll be sure to to keep the display connected if I need to reprogram.


Patrick
 

Leonard, I don't know if I ever completely answered this....

Patrick you should have 5 volts on vss pin. Check if you have it there to ground.
To answer this question pin 1 (GND) and 16 (Light -) are the only pins that show continuity directly to the ground

It's possible that I burnt the screen and/or received a bad screen. I have another on order but it won't come in until next week. I'll test the backlight prior to connecting when it comes in.

Also, I apparently overlooked the schematic during the build. I've been spending a lot more time looking at the schematic since all this started.
Pin 2 should be and is 5v
I don't know what the other pins should be but pin 15 is 5v as well but being that the display is listed as 5v I would assume the light is rated for 5v


Immo
 

On Tue, Feb 9, 2021 at 09:31 PM, Patrick wrote:
would assume the light is rated for 5v
hi Patrick,
the backlight is a combination of LEDs, maximal power consumption abt 450mW at about 4.5V. So a series R of min 10 ohms at 5V is needed to limit current. Without resistor maximal power is reached after some seconds and backlight lights no more...
ga es 73
Immo