Shop OBEX P1 Docs P2 Docs Learn Events
No signal from vga connector? Problem solved! — Parallax Forums

No signal from vga connector? Problem solved!

E-HeadE-Head Posts: 13
edited 2010-01-12 11:48 in Propeller 1
Hi

I have a Propeller Education Kit + VGA-PS/2 Adapter Board Kit.
Now I have tried to test my system with different vga-demos. None
of them have not worked. When I connect a monitor to the Propeller's vga connector,
the monitor won't say anything.

What shoud I check to solve the problem and have you any good suggestions?

I am quite sure that there is not wiring problems and not any coding errors.

Post Edited (E-Head) : 1/12/2010 10:12:39 AM GMT

Comments

  • Toby SeckshundToby Seckshund Posts: 2,027
    edited 2010-01-11 10:54
    Asumming there are no wiring of software problems, will the VGA monitor accept the resolutions that are being thrown at it?

    A while back there was a thread where the problem was that the whole propeller stopped, and the regulator got hot, when the VGA was plugged in. I surgested that it might be due to the PIN 9 of the VGA 15 pin being supplied with +5Volts and that may have been shorted to ground if the entire middle row was connected to GND. I never saw a reply to say if the problem had been sorted out, and by what method. PIN 9 gives +5Volts to the VGA monitor so that an EEPROM in it can be read to tell the computer what sort it is, etc. Props do not do that. Some older leads had the PIN 9 removed but not the modern ones.

    Do you have an oscilloscope to look at the syncs, are the H and V syncs on the right pins ie you haven't wired anything mirror imaged. The rear of the femail gives the 1-5 then 6-10 then 11 - 15. RGB on 1,2,3 with their shield nominally on 6,7,8. PINS 5 and 10 should be GND. The H syncs are on PIN 13, the V syncs on PIN14, the wrong way around will not work.

    An old glass vga monitor might give some clues before it shut down from no signal, LCD just sit there and sulk, if the input isn't good enough

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Style and grace : Nil point
  • E-HeadE-Head Posts: 13
    edited 2010-01-11 14:11
    Well, unfortunately, I don't have access to an oscilloscope. And I am sure that there is no kind of shor circuit. Could it be just a broke VGA adapter... because I tested it on another breadboard Propeller system and that adapter didn't work there either. And I tested too the codes and the codes were ok.
  • E-HeadE-Head Posts: 13
    edited 2010-01-11 14:42
    I am close to solve the problem. It seems that the problem is in the connection from adapter board "pin v" to the VGA- connector pin 14. But I can verify that at earliest tomorrow.
  • E-HeadE-Head Posts: 13
    edited 2010-01-12 09:36
    Well, the problem is solved. There was a broken resistor on the adapter board. It was behind the "pin v" and was 240 ohms. My supervisor replaced it and now the VGA connector works fine [noparse]:)[/noparse]
  • Toby SeckshundToby Seckshund Posts: 2,027
    edited 2010-01-12 11:48
    Well done, have fun.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Style and grace : Nil point
Sign In or Register to comment.