colecovision wonkey graphics

[Logicdustbin]

whats going on here:

now its in Russian?


?

[MaxWar]

Id swear Ive had the same issue caused by bad contact in the cart connector. Obviously the first thing to look for.
I even had a Bent pin in my coleco connector.

[ColecoFan1981]

whats going on here:

now its in Russian?


?

I'd like to see what the first level stage looks like all garbled up that way.

~Ben

[ApolloBoy]

Looks like you have a dirty power switch. What happens is that the power switch gums up overtime and causes one or more of the voltage rails not to be switched on properly. The video RAM chips on the CV use three different voltages (5V, 12V and -5V), so if one of those rails isn't working it'll cause weird graphical glitches. IMO, a better fix would be to replace the VRAM chips with newer ones that only use a single voltage rail (specifically 5V), and you'll never have to worry about garbled graphics again.

[Logicdustbin]

I searched on google, some claimed that it was the DRAM chips, I replaced them and it is still there,

I cleaned the cart slot, but didn't check the pins, I'll try that and change the switch too.


will update if this fixes it in case others have this issue too

[Logicdustbin]

nope

change the switch, and serviced the cart slot.

guess I should look at the ram chips again....

[APE992]

Could be your power brick. You said you replaced the DRAM chips, did you use those that don't need 12v? I have two power bricks and one produces roughly the same result as yours due to the 12v lines being a bit screwed up on the brick. The other works fine.

[Logicdustbin]

Could be your power brick. You said you replaced the DRAM chips, did you use those that don't need 12v? I have two power bricks and one produces roughly the same result as yours due to the 12v lines being a bit screwed up on the brick. The other works fine.

I measured the brick with a multimeter, and they were fine.

I have a few coleco power bricks, guess it won't hurt to try them out.

and I replaced the 8 ram chips at U15, these do not require the -5v. maybe my google results were suggesting different chips then the ones I replaced...

[ApolloBoy]

and I replaced the 8 ram chips at U15, these do not require the -5v. maybe my google results were suggesting different chips then the ones I replaced...

Did you use 4164s? Those only need the 5V rail and you need to make a couple of small modifications to the board in order to use them. Here's some details: http://console5.com/wiki/Colecovisio...M_Modification

[Logicdustbin]

Did you use 4164s? Those only need the 5V rail and you need to make a couple of small modifications to the board in order to use them. Here's some details: http://console5.com/wiki/Colecovisio...M_Modification

yes, this is where I bought the chips.

[FABombjoy]

If you have clean +5v then it may be the TMS9928. Does yours still have the heat sink on it?

[Logicdustbin]

If you have clean +5v then it may be the TMS9928. Does yours still have the heat sink on it?

yes, still have the heat sink....

[FABombjoy]

I've seen them fall off and that will kill them fast.

You could try hot / cold cycling the TMS chip and see if the graphics change. I had one once with a similar problem. Worked fine frozen, would corrupt then go blank when heated.