 Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me. |
Forum Index : Microcontroller and PC projects : Original Maximite Color VGA Issue
| Author | Message | ||||
| Vampire05 Regular Member  Joined: 06/12/2020 Location: GermanyPosts: 88 |
Hi guys, I have a problem with my new original Maximite Color. I soldered everything cleanly, but when I turn it on, my monitor tells me there is a sync error  . I have tried several monitors and power supplies. Always the same. Where could the error be?Best Regards |
||||
Geoffg Guru  Joined: 06/06/2011 Location: AustraliaPosts: 3292 |
There is not a lot to go wrong. If, as you say, you have tested it on a number of monitors that will eliminate the monitor. The next thing I would check is the 8Mhz crystal. Is it the right value? Is it damaged (too much soldering heat)? Are the padding caps correct and in place? If you have an oscilloscope it would be handy to see exactly what is on the sync pin. Geoff Geoff Graham - http://geoffg.net |
||||
Turbo46 Guru Joined: 24/12/2017 Location: AustraliaPosts: 1642 |
You could also check the soldering around this part of the circuit - to the VGA connector and the chip.  Bill Keep safe. Live long and prosper. |
||||
| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 5091 |
Hi Vampire05, Did you build a "Color Maximite", or did you build a "Color Maximite 2" in original configuration (with the Waveshare board on top) ? Color Maximite  Color Maximite 2  Edited 2021-04-01 16:33 by Volhout PicomiteVGA PETSCII ROBOTS |
||||
| Vampire05 Regular Member Joined: 06/12/2020 Location: GermanyPosts: 88 |
First of all, thank you for your help! @Volhout: I have the original Maximite Color (first version). @Turbo 46: I have checked the soldering around the circuit - to the VGA connector and the chip. Everything seems to be right. @Geoffg: I checked the Crystal with the oscilloscope: I checked Gnd<->Left crystal pin and also Gnd<->Right crystal pin. One pin has a higher Level than the other one. Thats strange???? I have ordered a new 8MHz Crystal.  |
||||
| Vampire05 Regular Member Joined: 06/12/2020 Location: GermanyPosts: 88 |
By the way: Are the DS1307 and the battery necessary? |
||||
| Vampire05 Regular Member Joined: 06/12/2020 Location: GermanyPosts: 88 |
Here some images. The error: Invalid Horizontal: 14.7 K  The Crystal:  Pin13 and 14:   |
||||
| Frank N. Furter Guru Joined: 28/05/2012 Location: GermanyPosts: 949 |
Hi Vampire05, where are you located in Germany? I built my Color Maximite with a UBW32 board... :)Frank |
||||
| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 5091 |
Hi Vampire05, Good that you can show these pictures. I cannot see what scale they are but the lower picture definitely looks wrong. It should show logic levels and only the edges are shown on your scope. Are you sure you are connecting this to a VGA input of a monitor. I have only once in my life seen such behaviour, and that was when I connected a logic signal to a SVHS C input (the color pin, not the luminance pin). There was an internal bandpass filter in the monitor that cause this behaviour. So I expect somewhere there is a short circuit. Either in the cable, or in the board associated with pin 14 (vertical sync). Please note with each picture the horizontal and vertical settings. Is the crystal running at 8MHz (125ns period)? I have a color maximite like yours, and will confirm the horizontal frequency tonight. I am at work now. Maybe your monitor is confused because the corrupted vertical sync. Regards, Harm PicomiteVGA PETSCII ROBOTS |
||||
| Frank N. Furter Guru Joined: 28/05/2012 Location: GermanyPosts: 949 |
Is it possible that the board runs in PAL mode??? :)Frank |
||||
| Geoffg Guru Joined: 06/06/2011 Location: AustraliaPosts: 3292 |
There is the clue. It is outputting PAL composite video. Your monitor must be grounding Pin 9 of the VGA connector. This is mentioned in the Frequently Asked Questions (https://geoffg.net/MaximiteFAQ.html ) as follows: You can also cut the PCB track to pin 9 but upgrading to the latest version of MMBasic is a better option. No. It will work fine except that the time is lost on a reboot. Geoff Geoff Graham - http://geoffg.net |
||||
| Vampire05 Regular Member Joined: 06/12/2020 Location: GermanyPosts: 88 |
@Frank ich komme aus Guetersloh (naehe Bielefeld) ;-) @Volhout / Geoffg: unfortunately cutting the track to pin 9 did not help, but the update was the key. Now it works guys  Thank you all for your help, you are the best  |
||||
| Frank N. Furter Guru Joined: 28/05/2012 Location: GermanyPosts: 949 |
@Vampire05 Glad you solved the problem! Have fun with your Color Maximite! Guetersloh is unfortunately not near me - I come from Franconia - near Nuremberg... :)Frank |
||||
 Print this page |
 |
The Back Shed's forum code is written, and hosted, in Australia. | © JAQ Software 2025 |
