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ColecoVision Console Problem


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Hey all. I bought a ColecoVision from eBay. It works, but the graphics are garbled, so is there anyway to get this problem fixed?
 
 
EC1388E4-2A65-42D5-94C3-BECDE9AF9D1B.thumb.jpeg.d1bd3635ffef1cad559a3ea6390b7630.jpeg
I believe this is the common problem with bad RAM. As I recall, people replace the RAM with 5-volt RAM and mod the console for it.
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39 minutes ago, CZroe said:
2 hours ago, Retro_Game_Lover96 said:
Hey all. I bought a ColecoVision from eBay. It works, but the graphics are garbled, so is there anyway to get this problem fixed?
 
 
EC1388E4-2A65-42D5-94C3-BECDE9AF9D1B.thumb.jpeg.d1bd3635ffef1cad559a3ea6390b7630.jpeg

I believe this is the common problem with bad RAM. As I recall, people replace the RAM with 5-volt RAM and mod the console for it.

That should definitely fix the problem.

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38 minutes ago, doubledown said:

Or possibly the power supply, or possibly the On/Off switch.

This....

 

Last CV I modified for a client was doing the same thing. Just had to clean up the power port plugs and the switch to make it look proper again. In fact, it was looking just like your screen cap. Client still had me change out the slide switch for a rocker to be on the safe side though.

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15 minutes ago, -^CrossBow^- said:

This....

 

Last CV I modified for a client was doing the same thing. Just had to clean up the power port plugs and the switch to make it look proper again. In fact, it was looking just like your screen cap. Client still had me change out the slide switch for a rocker to be on the safe side though.

 

Replacing with a rocker is nearly a must IMO. Those old sliders are toast after almost 40 years.

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1 hour ago, Retro_Game_Lover96 said:

http://cvaddict.com/article.php?articleid=19

 

This site I just discovered about the bad DRAM chips, and one of them looked like my image, so this could be the bad U15 chip.

The point that the others were making, though, is that if the system doesn't get adequate power, then those chips don't get adequate power, and you get the same symptom as if the chip was defective.  Each of those chips need 3 voltages:  +5, -5, and +12.  The two positive ones come through the slide switch.  So if the switch is bad, or if only one of the voltages from the power supply is bad, or for any other reason the chips don't get adequate power for their requirements, then you'll see something like this.

 

So the point is, don't replace your motor before checking if you're out of gas.  You can measure the voltages at C41, C42, and C43.  One side of each will be ground and the other side will be the power rail.  All 3 are to the left of the video chip.

 

In your case, the errors seem consistent with bad U12.

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Did you try to put a game in the console?    What happens after you passed the introscreen and the skill select screen? Does the game looks good?

 

Seeing you picture,  i would say that it is not the Original Bios , ..as said ChildofCV  as a joke but may be not... , could be a russian Hack of the BIOS.

 

That's very strange that we can read    (c)1982  CKHACK  ...

 

And it is very strange also that if you see "garbadge"  "random" characters like you see, someone else  can see EXACTLY the same sequence.

Follow the link below.

 

 

Or you bought his console!!!

 

 

 

 

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Many of the mistakes show an off-by-4 error.  For instance,

         PQRJ
+        44 4
-------------
         TURN

         CAIA
+        4 44
-------------
         GAME

          KBB
+         444
-------------
          OFF

       BABKRA
+       444 4
-------------
       BEFORE

    IJSARPIJC
+    4 4 4 44
-------------
    INSERTING

    CARPRI@CA
+      4  444
-------------
    CARTRIDGE

           KR
+          4 
-------------
           OR

    AXPAJSIKJ
+   4   4  44
-------------
    EXPANSION

      IK@QHA*
+     4444444
-------------
      MODULE.

The (c) is supposed to be 00011101, but ends up as 00011001, which is undefined by the CV character map and blank.

 

So bit 2 seems to be zero for the most part.

 

Also for the numbers,

1 = 00100001

9 = 00101001

8 = 00101000

2 = 00100010

 

Since all 4 of these digits have bit 2 = 0, they are unaffected.

 

 

 

Anyway, how do the voltages read?

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24 minutes ago, ChildOfCv said:

That may be useful, but the voltages are needed elsewhere too.  You should at least measure them.

 

Anyway, those eBay chips fit the profile for the 5V mod.  The remaining question is whether they fit the specs or are just relabeled trash.  Unfortunately, you won't know until you try.

Basically, there was a video about it as well.

 

 

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That may be useful, but the voltages are needed elsewhere too.  You should at least measure them.

 

Anyway, those eBay chips fit the profile for the 5V mod.  The remaining question is whether they fit the specs or are just relabeled trash.  Unfortunately, you won't know until you try.

I think I recall someone making a custom PSU who left out one or two voltages after doing the 5v RAM mod... definitely saw someone suggest that you no longer need -5v into the console after the +5v RAM modification. If so, the +5v memory mod could conceivably bypass an issue with the PSU but -5v doesn't come through the power switch anyway as I understand it.

 

The system is definitely getting 5v but even if the +5v memory mod would bypass any issue with +12v at the switch, I'd still clean it up and add a dielectric grease. "Bulb grease" from an auto parts store often works wonders on the inside of old blackened and pitted switches and it sounds like these are particularly prone to that.

 

The system is definitely getting +5v. I doubt he'd see the same error every time if he wasn't getting 12v but, you're right, it can't hurt to check the switch and voltages first.

 

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All 3 voltages are needed by the old memory chips, and a bad switch can still provide some power.

 

+12V is needed by the RF modulator and video selector circuit, and -5V is used at the input controller.  So all 3 are still useful.  I think the project you're talking about was to place the contents of a CV into a portable case with screen.  It has a single supply, but it uses converters to get the other voltages.

Edited by ChildOfCv
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All 3 voltages are needed by the old memory chips, and a bad switch can still provide some power.
 
+12V is needed by the RF modulator and video selector circuit, and -5V is used at the input controller.  So all 3 are still useful.  I think the project you're talking about was to place the contents of a CV into a portable case with screen.  It has a single supply, but it uses converters to get the other voltages.

Makes sense. The place I was sure I saw someone mention that it removes the need for -5v was this last post in this thread:
http://www.ukvac.com/forum/colecovision-power-supply-alternative_topic356004.html

Of course, he doesn't say he actually did or confirmed it, so I defer to you. :)
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