Jump to content

Photo

Black Screen issue with Colecovision


33 replies to this topic

#26 vgcollector ONLINE  

vgcollector

    Space Invader

  • Topic Starter
  • 19 posts

Posted Mon Feb 11, 2019 5:09 PM

I am sorry I did not received any notifications after my last input.
I see you have been making significant progress and happy you have been assisted by a true expert (childofcv).

Did you say you have 3 colecovisions doing the same thing?

Before you do anything else, I would try a different tv set.
Just my 2 cents

Regards!

Al

I have used the tv set with my working Colecovision and it does fine. I am pretty good at eliminating problem possibilities.I use my good Colecovision to test the RF cable, TV, and power supply. I hope to test with the logic probe before the end of the week. Thanks for your assistance.

 

Vgcollector



#27 alortegac OFFLINE  

alortegac

    Chopper Commander

  • 194 posts

Posted Mon Feb 11, 2019 5:12 PM

Ok, then I misunderstood you said you have 3 consoles doing the same black screen.(?)

#28 vgcollector ONLINE  

vgcollector

    Space Invader

  • Topic Starter
  • 19 posts

Posted Mon Feb 11, 2019 6:04 PM

You had it right. I have one working one and then 3 with the same black screen issue. Thanks



#29 vgcollector ONLINE  

vgcollector

    Space Invader

  • Topic Starter
  • 19 posts

Posted Mon Feb 18, 2019 6:39 AM

Connect the black lead to ground.  If you connect it to -5 and +5, that would be a 10V difference and would probably kill the probe.  Don't try to probe negative or +12V lines with it.

 

As long as you know what to expect, it's useful.  It can certainly tell you if the clock inputs are working (flashing lights), and if the +5 and gnd pins are good.  You can poke at data and address lines to see if any communication is going through the system.  For instance, the RFSH, M1, and MREQ lines from the processor should always be blinking.  Any clock line should be blinking.  If any data or address line is making it to the chip, chances are it will be blinking too.  The higher address lines (A15 through A10 or so) may not be too active, especially without a cartridge in.

 

Chip selects are trickier though, as they will only go low when that particular chip is singled out for communication.  The ROM chip's CS pin will probably be blinking though, possibly even both SRAM chips.  Audio and video output won't be digital, so who knows what the probe would say looking at any of them.

 

As a start, look at U22 pins 2, 4, 6, 8 and 10.  They should be blinking.  Same for U8 pins 6, 5, 8 and 9.  Just for grins, U8 pin 13 should be high and pin 7 should be low, though it's because these are hard-wired to power and ground respectively.

 

U7 pin 4 should be blinking.  Pins 11 and 12 should be low and U7 pin 10 should be high.

Getting closer to using the probe, but I don't want to damage it from the start. If you were using the logic probe on the Colecovision where exactly would you connect the black and red clips.I am looking for specific locations so I connect them to the correct spot. Thanks again for your help.



#30 ChildOfCv OFFLINE  

ChildOfCv

    Chopper Commander

  • 185 posts

Posted Mon Feb 18, 2019 8:22 PM

1764007603.png

Here's where I'd attach them.  Just make sure the red one especially doesn't get pulled around to touch stuff that it shouldn't as you're probing around.



#31 vgcollector ONLINE  

vgcollector

    Space Invader

  • Topic Starter
  • 19 posts

Posted Mon Feb 18, 2019 8:45 PM

attachicon.gif1764007603.png

Here's where I'd attach them.  Just make sure the red one especially doesn't get pulled around to touch stuff that it shouldn't as you're probing around.

Great picture. The black clip is attached to the frame of the power switch, but what is the red clip attached to? I appreciate the detailed picture. I just want to make sure I am doing it right.



#32 ChildOfCv OFFLINE  

ChildOfCv

    Chopper Commander

  • 185 posts

Posted Mon Feb 18, 2019 10:33 PM

It's a large choke that the +5V runs through.



#33 vgcollector ONLINE  

vgcollector

    Space Invader

  • Topic Starter
  • 19 posts

Posted Tue Feb 19, 2019 6:26 AM

It's a large choke that the +5V runs through.

Ok, thanks. I see what you are connected to now. I couldn't see the tip of clip connected until you told me where it was connecting. Thank you again. I will let you know what I find. I hope to get this done in the next couple of days.



#34 MarcusFrom1982 OFFLINE  

MarcusFrom1982

    Space Invader

  • 21 posts

Posted Tue Feb 19, 2019 10:36 PM

Clean the power supply plug sockets and the plug pins in the back of the colecovision. This can do WONDERS!




0 user(s) are browsing this forum

0 members, 0 guests, 0 anonymous users