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Turning my Coleco on just gives noisy static, no picture whatsoever

Colecovision problem power supply rf voltage power switch static repair help

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#1 WebRat OFFLINE  

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Posted Thu Jan 23, 2014 9:11 PM

Hello!

 

I'm having a problem with my Colecovision the past couple of days.  It's been working great for a couple years now.  It was working fine just a couple days ago, but suddenly now it only displays mostly static on the screen when I turn it on.  There is no visual of any game/startup screen.  

 

The attached pic shows the pattern of static I see.  Sorry, it's sideways.

The top quarter of the tv is plain black, but then there's like a reddish line and the rest is static (although the bottom quarter seems yellowish).

 

I've tried using different RF Adapters and cables and it's the same problem (maybe the colours a little less noticeable, but same issue).  For now, I'm just using a direct cable connection to the tv.

 

I've already taken apart the power switch to clean the contacts on its top and bottom halves.  No change.

 

Another piece of info.  I recently checked out the voltage readings reaching the main board from the power supply.

When the power is off:

Blue:  -4.6 V

White:  4.75 V

Red:  9.7 V  --Wait, isn't that a bit far off?

Then I turn the power on and here are the readings:

Blue:  -4.6 V  (same as before)

White:  4.75 V (same as before)

Red:  6.4 V -- Is this supposed to happen when the power is turned on??

 

I'm worried that the problem could be the RF Modulator.  But those power supply readings seem strange, but I don't know why the system would work fine for years and then suddenly this would be the problem.

Anyway, based on this info, and the picture attached, does anyone have any suggestions/ideas of the problem and how to fix?

 

Thanks, all.

Attached Thumbnails

  • photo (1).JPG

Edited by WebRat, Thu Jan 23, 2014 9:11 PM.


#2 thecrypticodor OFFLINE  

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Posted Fri Jan 24, 2014 4:55 AM

There is something definitely wrong with that PSU. It should be -5v 5v 12v. I'd bet it's one of the two tip41 transistors that's bad that's dragging the 12v line down.

Either you can try another PSU or you can try to replace both the tip41 transistors. Also it'd be a good ideal to also replace the electrolytic capacitors in the supply.


Edited by thecrypticodor, Fri Jan 24, 2014 4:58 AM.


#3 WebRat OFFLINE  

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Posted Fri Jan 24, 2014 6:01 AM

There is something definitely wrong with that PSU. It should be -5v 5v 12v. I'd bet it's one of the two tip41 transistors that's bad that's dragging the 12v line down.

Either you can try another PSU or you can try to replace both the tip41 transistors. Also it'd be a good ideal to also replace the electrolytic capacitors in the supply.

Thanks for the reply.

Yeah, I wasn't sure if a bad PSU would result in the screen reacting like that or if the system would just not run at all.

I'd rather not mess with the insides of a PSU, so my next move will be to get another one.  Does anyone know a place I can get a reasonable price on just a PSU that ships to Canada (besides ebay)?  



#4 thecrypticodor OFFLINE  

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Posted Fri Jan 24, 2014 6:42 AM

Honestly ebay would be your best bet. Currently there is no one making CV PSU replacements. So it doesn't matter where you could go you'd have to get a old one. Alternatively there's a user around here by the name of Yurkie that does CV mods. He was talking about offering some kind Power supply mod service you can look into that if you wish.

http://atariage.com/...sted-and-ready/


Edited by thecrypticodor, Fri Jan 24, 2014 6:52 AM.


#5 GoldenWheels ONLINE  

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Posted Fri Jan 24, 2014 11:39 AM

Thanks for the reply.

Yeah, I wasn't sure if a bad PSU would result in the screen reacting like that or if the system would just not run at all.

I'd rather not mess with the insides of a PSU, so my next move will be to get another one.  Does anyone know a place I can get a reasonable price on just a PSU that ships to Canada (besides ebay)?  

I got a lot of 3 systems with only one PS recently (which I of course kept). I gave one Colecovision to my step-brother and said "ill watch ebay for you for a cheap PS".

 

They don't seem to exist webrat. Most I see are 50$ by the time the auction ends, and I've been checking every day for a month.



#6 NIAD OFFLINE  

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Posted Fri Jan 24, 2014 6:09 PM

Sometimes you get lucky on eBay and can land a Power Supply for a lot less than $50, but there is no guarantee that it works properly even if the seller states that it does. For instance, it might output enough juice to handle one particular cart, but you may experience problems using a different cart due to how much the game taxes the system. A couple good examples of this are Lord of the Dungeon and the AtariMax SD MultiCart.

 

I would check around on eBay and www.atari2600.com as well as a couple other retro sellers and then compare what it would cost to send your system to Yurkie to have him refurbish and mod your system for use with a MODERN power supply that should eleviate any concerns for many years to come. That reminds me, I still need to send Yurkie one of my systems to have the power supply mod done! Maybe I'll drop it off to him in July on my way to Cleveland for the ADANcon.



#7 ValkerieSilk ONLINE  

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Posted Sat Jan 25, 2014 1:41 PM

Run to the light Carol Anne

#8 SiLic0ne t0aD OFFLINE  

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Posted Sat Jan 25, 2014 4:34 PM

I may have another working spare PSU, I'll look around..

#9 WebRat OFFLINE  

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Posted Wed Jan 29, 2014 4:35 PM

Yup, it was the PSU, all right.

 

I got a replacement, and now we're back in business.   :-D  

I can play my beloved Frenzy game (Frenzy is the best game of all time -- you can agree with that or you can be wrong ;) ).

 

This PSU is different from my original.  The giant brick part on my original had the power prongs on it whereas the new one has a cord and normal plug coming out of the brick (much nicer for power bars and wall sockets).

Thanks for the help, everyone.  I really appreciate it.



#10 NIAD OFFLINE  

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Posted Wed Jan 29, 2014 7:56 PM

This two-wire PSU that you just purchased is the power supply supplied with all CV systems sold in Canada. It is said and I have to agree from my own use to be a lot more reliable. The PSU with the power prongs built-into the case is the version that came with CVs in the U.S.A.



#11 SiLic0ne t0aD OFFLINE  

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Posted Thu Jan 30, 2014 2:17 PM

Good score there! Although I don't need one, I wish I could find a Canadian PSU somewhere for cheap.. Someday perhaps. ;-) I have enough US versions already.. Haha

#12 Devalis OFFLINE  

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Posted Tue Feb 4, 2014 11:14 PM

having a similar issue with my coleco, except I just get black static with a steady tone that changes when you power cycle the unit.  All voltages seem to be normal though.







Also tagged with one or more of these keywords: Colecovision, problem, power supply, rf, voltage, power, switch, static, repair, help

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