Date
1 - 11 of 11
QCX-Mini Display Issue
|
Ernie Bailey - N2DGQ
I have just completed my second QCX-Mini this one for 20M. Upon power up the display was one (1) row of blocks. In looking at the troubleshooting procedures by Ron WA7GIL, item #2
IC2 may not be getting power. Check for 5 volts on pins 7 and 21 of IC2. If either is missing check for open condition in L6 and L5 respectively. This is easily done by checking for 5 volts on both sides of each inductor. I found pin #7 has +5VDC, but pin #21 is not getting +5 VDC. CheckingL6 & L5 they both have +5VDC on each side. C35 which is tied to pin 21 does not have +5vDC either. I have checked and resoldered all pins for IC2 as well as the header connector pins connecting both boards. IC2 is seated properly. I am stumped. Could IC2 be defective? Any further troubleshooting ideas would be helpful. |
|
|
|
Hi Ernie, since I wrote that procedure, I take full responsibility for an obvious mistake in it and will send a correction to Hans tonight. That was supposed to say pins 7 and 20 (not 21). There will not be any voltage on pin 21. Please look for 5 volts on pin 20. It probably is there since you saw it on both sides of both inductors, but make sure. After that one of the suggestions is to look for soldering issues between IC2 and the display board. Since the display is on a separate board on the mini, pay close attention to the soldering of the pins on the interconnects between the two boards. Ground pins especially need extra heat to get good connections. You can also use an ohm meter to verify connections from the Display to IC2. The schematic will show which leads connect to where between these two devices. It's a little cumbersome with the Mini but you can do it if you turn the unit up on its side and measure from top of the display board to bottom of the main board on IC2 pins. If a particular connection isn't there that's supposed to be, check soldering and also try to isolate if it's on the main board or the display board. On very rare occasions I have found an open circuit trace that isn't even visible with the eye. It can usually be easily repaired with a jumper wire if that's the case. Hope that helps ... Ron On Thu, Mar 24, 2022 at 5:24 PM Ernie Bailey - N2DGQ <ebrcdddcdc@...> wrote: I have just completed my second QCX-Mini this one for 20M. Upon power up the display was one (1) row of blocks. In looking at the troubleshooting procedures by Ron WA7GIL, item #2 |
|
|
|
Ernie Bailey - N2DGQ
Ron thanks for your reply. Yes, I did see +5VDC on pin #20. I will check tomorrow for continuity as you suggest. I'll post again with my results.
|
|
|
|
Ernie Bailey - N2DGQ
Ron,
Good afternoon. I have verified the problem is on the main board. I was able to swap out the new display and new microcontroller to my working 40M rig. The display worked, and the microcontroller indicated to Select Band as per the first alignment procedure. I then checked continuity of pins on IC2 socket and the 2x5 male and female connector pins. All checked out good. Next, I wanted to check for continuity per your suggestion from IC2 to the display according to the schematic diagram. Upon that review I became a bit confused as what I thought was a direct connection but was not. All connections go to the blue line on the schematic. Unfortunately, my troubleshooting skills are lacking so I'm not sure what that blue line represents. I need a little more guidance. While looking at the schematic for IC2 pin connectivity, do I assume for example pin #2 says "LCD D4" assume that pins goes to Display pin #4? And pin #3 says "LCD D5", assuming connects to Display pin #5? So on and so forth for all IC2 pins with designations of LCD. Also Display pinout on the schematic except for VCC, GND and 12VDC, dose not make sense to me. Thanks in advance for your guidance. |
|
|
|
Alan G4ZFQ
On 27/03/2022 18:22, Ernie Bailey - N2DGQ wrote:
All connections go to the blue line on the schematic.Ernie, This just represents a bundle of wires. A harness. While looking at the schematic for IC2 pin connectivity, do I assumefor example pin #2 says "LCD D4" assume that pins goes to Display pin #4? And pin #3 says "LCD D5", assuming connects to Display pin #5? Pin 2 enters this harness as LCD D4, and comes out with the same designation going to LCD pin 11. (DB4) Just go round the blue line looking for matches. (Watch out, on a few occasions a connection may go to two places.) 73 Alan G4ZFQ |
|
|
|
Ernie, sorry I just got back from Church and lunch. Alan is correct. I keep an old copy of the QCX Classic schematic around because it has the LCD pinout on the same page. Easier for me to figure it out. Function IC2 pin LCD pin LCD D4 On Sun, Mar 27, 2022 at 12:16 PM Alan G4ZFQ <alan4alan@...> wrote: On 27/03/2022 18:22, Ernie Bailey - N2DGQ wrote: |
|
|
|
Oops. Try that again ... LCD4- IC2 pin 2 to LCD pin 11 LCD D5 - IC2 pin 3 to LCD pin 12 LCD6 - IC2 pin 4 to LCD pin 13 LCD 7 - IC2 poin 5 to LCD pin 14 LCD EN - IC2 pin 6 to LCD pin 6 Hope that helps ... Ron On Sun, Mar 27, 2022 at 12:38 PM Ron Taylor <wa7gil@...> wrote:
|
|
|
|
Mont Pierce KM6WT
On Sun, Mar 27, 2022 at 11:22 AM, Ernie Bailey - N2DGQ wrote:
While looking at the schematic for IC2 pin connectivity, do I assume for example pin #2 says "LCD D4" assume that pins goes to Display pin #4? And pin #3 says "LCD D5", assuming connects to Display pin #5? So on and so forth for all IC2 pins with designations of LCD.Hi Ernie, Actually it's a bit simpler then that, and no assuming necessary. It's a common practice when a schematic gets busy with lots of lines connecting different components to shorten the line to a short stub and "Label" it. Anytime you see a schematic line stop with a label name, you can look for that label name throughout the schematic. I actually like the QCX+ Black&White Hi-Res schematics Hans added to the QCX+ page. It's easier for my eyes to see... And since ALL QCXs, although they don't share the same "physical" layout, the do follow the same basic schematics, these image are very helpful. The following links can also be found on the QRP-Labs QCX+ webpage (click here). Just above the bold "Firmware" heading. Click Here for Main board schematics Click Here for Display board schematics Click Here for combined two page pdf with both the above schematics. On the Display board schematics, you will see: These labels match exactly the labels on the Main board schematics next to the processor: 73 km6wt |
|
|
|
Ernie Bailey - N2DGQ
To All,
Many thanks for your very helpful suggestions. After understanding the schematic diagram flow from IC2 to Display, (and general circuit labeling, thanks KM6WT) I conducted the continuity check. All checked out. Understanding the microcontroller was not getting commands, I decided to check out the other connections pertaining to the microcontroller. I started at XTAL1, and guess what............I completely skipped over that installation and went for the TCXO installation. WHAT A DOPE!!!! I installed the crystal and boom up comes the display. I was hoping there was a simple explanation, and it was. Now I can resume with the alignment. I hope this was the only issue I'll have. Thanks again to all who supported me. I received a good education. |
|
|
|
jjpurdum
Ernie: Anyone who says they built something without at least one "flat forehead mistake" (you know--where you slam the heel of your hand into your forehead while mumbling "How could I be that stupid?") is probably pulling your leg. Most programmers have extremely flat foreheads... Jack, W8TEE
On Monday, March 28, 2022, 02:25:27 PM EDT, Ernie Bailey - N2DGQ <ebrcdddcdc@...> wrote:
To All, Many thanks for your very helpful suggestions. After understanding the schematic diagram flow from IC2 to Display, (and general circuit labeling, thanks KM6WT) I conducted the continuity check. All checked out. Understanding the microcontroller was not getting commands, I decided to check out the other connections pertaining to the microcontroller. I started at XTAL1, and guess what............I completely skipped over that installation and went for the TCXO installation. WHAT A DOPE!!!! I installed the crystal and boom up comes the display. I was hoping there was a simple explanation, and it was. Now I can resume with the alignment. I hope this was the only issue I'll have. Thanks again to all who supported me. I received a good education. |
|
|
|
Mark
Quoting Jack:
Anyone who says they built something without at least one "flat forehead mistake" (you know--where you slam the heel of your hand into your forehead while mumbling "How could I be that stupid?") is probably pulling your leg. Most programmers have extremely flat foreheads...You are so correct. My favorite was when my Jeep back doors would not unlock from inside. Turns out I had enabled the child safety lock feature somehow. 73! Mark K9TR |
|
|