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VGA Problem — Parallax Forums

VGA Problem

SANSAN Posts: 29
edited 2010-03-31 23:09 in Propeller 1
Hi!
I have a Propeller Protoptype Board. I soldered the VGA connector and registers properly.
After compiled the vga_demo.spin object (from 'Propeller Library - Demos') into it, when I am connection the board with a CRT monitor (desktop monitor)
the green led in the board is getting switched off and the voltage regulator becoming hot.
What should I do ?
But the chip is working now.

Comments

  • mikedivmikediv Posts: 825
    edited 2009-10-07 17:14
    San not sure I fully understand but if the reg gets excessively hot only when you plug in the VGA monitor then I would start looking there since you just added it right? look for solder shorts or backward parts or in wrong place I didn't catch which prop board you are using but if its the prop proto board from parallax make sure you used the right value resistors and put them in the right the place, my prop proto board had a resistor in wrong place and it caused me some problems
    Oh San you also didnt say how hot my reg does get a bit warmer when I am running the VGA monitor I actually had to add a heat sink and it only got hotter when the monitor was attached do the colors show up OK?
  • SANSAN Posts: 29
    edited 2009-10-07 17:23
    Thanx.
    But I checked so many times; I placed all the components in right place and there is mo shotr-circuit.
    Why the power led in the board is getting low when I'm connecting Monitor ?
    If the battery is down then can it be happened ?
    I'm using Propeller Proto Board (#32212)
  • Mike GreenMike Green Posts: 23,101
    edited 2009-10-07 17:31
    Like mikediv said, you must have a short circuit somewhere, probably around the VGA connector or resistors. It is not normal for the regulator to get significantly hotter when a VGA monitor is connected and the green LED should not go off. That's a sign of a short circuit. If you're running the Protoboard from a battery, it's possible that the battery can run down, but the regulator would not get hotter in that case.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2009-10-07 17:40
    I agree with Mike. Use a magnifier to inspect for shorts. It's very easy to miss a hair's width solder stalagmite that's bridging two pads. And having a groundplane surrounding all the throughholes makes a hard-to-find short even more likely, despite the soldermask.

    -Phil
  • RaymanRayman Posts: 14,880
    edited 2009-10-07 18:32
    I'd look closely around the 5V pins... I think·one of those·being shorted to ground is the only easy way to load it down that much...

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  • Toby SeckshundToby Seckshund Posts: 2,027
    edited 2009-10-07 18:53
    The VGA conector has 5V on pin 9. On most old VGA leads this pin was ommitted but all the other central pins are earths. If the pin9 is decked then you will get what you describe. Newer units use the +5V up pin 9 to power the eeprom in the monitor for plug+pray idents.

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  • James NewmanJames Newman Posts: 133
    edited 2010-03-31 18:16
    Think I may be running into this. I loaded the prop up with a program that uses vga last night. The last thing I did was power it up and double check all of the operation, all good. I took it to my workplace today and just tried it on a crt up here, and it did what is described above. Going to try another monitor in a bit...
  • Toby SeckshundToby Seckshund Posts: 2,027
    edited 2010-03-31 18:47
    I just leave the pin 9 open cct as there is no reason to probe the ident EEPROM in the monitor, if it has one. The SDA and SCL pins (13 + 15, I think) are never wired up on Prop boards.

    A mate at work gave up waiting for the skinflint management to upgrade his anchient laptop and started using a more modern one of his own. The second job he went out on happened to have a homemade VGA connection with all the central pins earthed. You could hear the laptops PSU screaching from across the room when he pluged it in. Thank god it was built tough.

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    Style and grace : Nil point
  • James NewmanJames Newman Posts: 133
    edited 2010-03-31 23:09
    Well, back home and it works. Neither of the monitors I use here have that pin in the middle row. I didn't get a look at the one at the shop, but it's a cord that is permanently attached to the crt. This does seem to be the problem, however. Would be nice to have a mention of it somewhere since it could potentially fry a regulator, or worst. Better yet, why don't we leave that connection off of the proto/demo/professional boards?
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