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So, as I'm tidying up wires and putting things back in place after simplifying the stereo/dash wiring, I've found that my LCD clock isn't working (1987 944 Turbo, btw).
How can I troubleshoot this?
Extra info:
• I replaced the LCD screen a few years ago. Never had any trouble with that
• When I took a closer look, one of the tracks (from the ground terminal) on the PCB appeared to be damaged. So I repaired it – LCD backlight started working again, but not the rest of the clock
you are a hero for going as far as you did, Those clocks were very cheaply made, and most stick a convenience store led clock over it! (LOL). Porsche has come out with a replacement that is far superior to the original and works well. Expensive though. All of the used ones are kaput as well
Thanks Doc. Well if I can fix the original Porsche thing, I'd usually rather fix the original Porsche thing!
And on the upside with those clocks, they may be cheaply made, but at least it's all discrete components rather than chips (apart from maybe behind the LCD) – seems like a reasonably competent electronics engineer should be able to diagnose and fix problems. But, sadly, I'm a bodger rather than a competent electrical engineer…
Yeah, I may just replace it – but I was thinking of maybe going with a DIY arduino-driven unit. That way I could have the original functionality via the original buttons, rather than stick a new clock on top
So after more fruitless tinkering with the original clock, I’m going to go ahead with making an Arduino-based replacement
It’ll use a GPS module to get the time, so will be millisecond-accurate, and it should be possible to get it to do an automatic correction for British Summer Time. Sweet! But that might be beyond my rather basic cut/paste/modify coding skills. But the stopwatch function should be easy enough to recreate
I did look around for an off-the-shelf clock to use, but couldn’t find anything with the right size and type of display
hmmm… so that attempt at embedding video didn't work. As I'm all geeked out for the weekend, you'll just have to imagine a breadboard, a display, and some wires.
Was looking to put an Arduino in my 86NA as a learning project, but realized there really isn't much to control. Even though my clock actually works, this might make me replace it.
As for the display, I sort of like the dated (read:944 era) look.
Interested to see where you put the GPS module. I have no experience with it, so not sure if it could work under the dash. And where are you pulling the temp from?
Yup, I did think about other displays, but like V17 I decided I preferred the low-rent, period-appropriate look, at least at first glance! The original clock was pretty cheap, so let's keep things that way ;-) Also, using LED rather than LCD means that I can skip the minor complication of using the dashboard lighting circuit for backlighting. (One possible future upgrade: add an ambient light sensor to enable automatic brightness adjustment).
I thought about a few fancier display options, mono and colour – having decided to go the Arduino route I started thinking, as one does, about what other stuff I could add to the project that would call for a bigger display. But keeping it simple was clearly smarter, so I decided on an old-school 4-character type
BTW, it was a little tricky finding a display with characters of the right size. The most common displays seem to have characters about 50% too big for the window in the dashboard, which was another reason I went with that particular display.
Temp and humidity come from a DHT22 sensor - cheap, seems to work fine. No idea how well the GPS signal will be picked up under the dash, will report back as soon as I find out! At the moment I'm planning to simple include the GPS module in the clock assembly itself, but I can imagine there could be an advantage in moving the antenna somewhere where it gets a slightly better view.
Last edited by zogster; Jan 6, 2020 at 11:09 AM.
Reason: corrected/clarified reference to display types
Having made a good start with this project I was frustrated by a couple of problems, like slow button response (turned out to be the temp sensor, which I changed for one using a Bosch BME280) and some slight display weirdness (turned out to be my sloppy coding, no surprise), that I wanted to sort out before assembling and installing.
So it's been on and off the back burner… long story short I've just tested my final prototype, and now have a working clock/stopwatch with added digital speedo and temperature display. I also replaced the GPS module a couple of times as I may have damaged one or more during testing and troubleshooting. Time is UTC only, and speed (in mph or kmh) is also from the GPS.
Final step: assemble in final form and install. I've just ordered a couple of circuit boards for the build, and WOWSAH, I had no idea it was quite so easy to design and lay out your own circuit board (never down that before), and then order a handful from a factory in China Which I did, in a few hours, and for only £11 (about $14).
BTW, the GPS module is the thing just to the left and above the display in that pic, and the temperature sensor is bottom right on the board, below the USB socket. The sensor can also do humidity and pressure, but I figured I'd already added enough unnecessary complexity
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LCD clock not working
