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Colecovision PSU help

Colecovision PSU PSU Repair

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#1 PsychoDave OFFLINE  

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Posted Wed Mar 15, 2017 6:10 PM

Hello everyone, I've got a quick question...

 

My Colecovision doesn't turn on, that is to say when I flip the power switch I get no picture on my TV.

 

I've replaced the power switch already with a Radio Shack DPDT Rocker - 275 691.  I've checked continuity

with my meter as well as voltage.  

 

When I check the PSU with the system in "Off" I get all the correct voltages 12v, 5v and -5v but when I

turn the switch on the 12v rail drops to 6v.  I checked voltages on the back of the plug receptacle and at the board

where the switch is connected.  A 6v drop seems to be a bit excessive...

 

So, where do I go from here?  Do I crack open the PSU or could there be an issue on the board?

 

Any help would be greatly appreciated.

 

Dave

 

 

 



#2 PsychoDave OFFLINE  

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Posted Thu Mar 16, 2017 9:02 PM

Cant find the edit button, sick of trying...

 

If someone can edit the 1st post to include this, awesome.  If not...no worries

 

I just wanted to add that ch 3 and 4 on my tv are static...always

When I power up the Coleco there is no image, no black screen

just static. 

 

I don't know if that helps...

 

Also, I'm thinking my problem could be a capacitor in the brick... 

 

Dave



#3 cdn2a OFFLINE  

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Posted Fri Mar 17, 2017 1:17 PM

It could be your powersupply or it could be something else dragging down your 12v line.

 

A crude method would be, to turn it on wait for a few seconds then touch the video ram

chips and see if one is hotter than the others. you can then start disconnecting chips from

the 12v rail till your voltage stabilizes.



#4 thecrypticodor OFFLINE  

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Posted Fri Mar 17, 2017 7:01 PM

I'd bet it's the power supply. All the CV powers supplies that I've worked on that had it's original capacitors were always out of spec. I've resurrected quite a few CV power supplies by simply just recapping them.

 

CV caps.png


Edited by thecrypticodor, Fri Mar 17, 2017 7:04 PM.


#5 coleconut OFFLINE  

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Posted Sat Mar 18, 2017 9:29 PM

I'd bet it's the power supply. All the CV powers supplies that I've worked on that had it's original capacitors were always out of spec. I've resurrected quite a few CV power supplies by simply just recapping them.

 

attachicon.gifCV caps.png

This is good to know, but what the challenge for me is the best way to open the darn things then put them back together so they dont look like some night-before-due school project.



#6 thecrypticodor OFFLINE  

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Posted Sat Mar 18, 2017 11:08 PM

This is good to know, but what the challenge for me is the best way to open the darn things then put them back together so they dont look like some night-before-due school project.

Sometimes you can get lucky and pop the plastic apart enough to start prying by applying pressure around the seem. I’ve also done it by sticking a flat blade screwdriver in between the slot for the strain relief and gently prying.

 

It's more likely than not you're gonna do some damage to the housing, but what’s more important it working or looking pretty.



#7 PsychoDave OFFLINE  

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Posted Sun Mar 19, 2017 12:46 PM

Apparently Radio Shack is going belly up again, unless they can find funding.  As a result all sales are final and no new shipments

are coming in.  After sifting through the component drawers I could only find 4 of the capacitors but they were axial, not radial.

I've ordered all the capacitors from amazon and should have them on Tuesday.  Now I just need to get a dremel so I can open up the housing.

 

What have people done to close the housing back up after cutting it open?  Plastic cement? 



#8 PsychoDave OFFLINE  

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Posted Tue Mar 21, 2017 11:49 PM

My parts arrived today and I've opened up the PSU case.

I didn't have a chance to work on it any more than that.

Here are a few pictures of the guts and I'll post more

as I replace the capacitors, hopefully it will help someone

down the road.

 

Dave

 

20170321_180026.jpg

 

20170321_223032_1.jpg



#9 Jess Ragan OFFLINE  

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Posted Wed Mar 22, 2017 4:47 AM

Do they have a viable alternative to these damned things yet? The CV I got didn't come with a power supply, and I'd prefer to avoid the standard model if at all possible. Just no sense in a five pound brick dangling from the wall.

#10 omf OFFLINE  

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Posted Wed Mar 22, 2017 9:19 AM

I had a dead colecovision power supply once, I had to throw it away.  i cracked it open to look into fixing it and it had grey epoxy over everything. it was not a thin coating, it was full to the brim.

it would have taken many weeks to get all that shit off which i was not prepared to do.  i was a bit pissed to be honest, why do that!!!!!!



#11 PsychoDave OFFLINE  

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Posted Wed Mar 22, 2017 6:13 PM

Well, I've finished swapping out all the capacitors in the PSU.  After temporarily 

covering it back up and plugging it in, I've got all the correct voltages.  12 VDC,

-5 VDC and 5 VDC with no load.  However, as soon as I turn the coleco on the

12v rail drops to 6v again.  So, either my PSU is just bad or something else is

wrong...

 

Any Ideas?  I guess ill check the video ram as suggested by cdn2a

 

Here is an album of pictures I took while swapping out the caps. 

http://smg.photobuck... Capacitor swap

 

Sample pic:

20170322_153411.jpg



#12 rassafrassa OFFLINE  

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Posted Sun Oct 29, 2017 8:15 PM

Did you figure out the problem? I have the exact same problem on 2 different systems- this is the only reference I can find online

 



#13 imstarryeyed OFFLINE  

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Posted Tue Oct 31, 2017 11:21 AM

I just got some chips in and I am experimenting with converting an XBOX 360 green brick power supply to colecovision.  I too hate the power supplies and do not wish to use an arcade power supply if I can avoid it.



#14 shabazz18 OFFLINE  

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Posted Tue Oct 31, 2017 8:07 PM

Your 12v regulator is bad. Mine had the exact same problem. I just installed the kit from console 5 since it has everything.

https://console5.com...ly-cap-kit.html

Edited by shabazz18, Tue Oct 31, 2017 8:07 PM.


#15 shabazz18 OFFLINE  

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Posted Tue Oct 31, 2017 8:32 PM

Did you figure out the problem? I have the exact same problem on 2 different systems- this is the only reference I can find online
 

Bad 12v regulator

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#16 towmater OFFLINE  

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Posted Tue Oct 31, 2017 8:35 PM

Suggest doing a 5V only mod, possibly cheaper than resurrecting the beast.



#17 shabazz18 OFFLINE  

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Posted Tue Oct 31, 2017 8:38 PM

Suggest doing a 5V only mod, possibly cheaper than resurrecting the beast.

That won't help with a 12v-6v voltage drop under load. Nothing wrong with the console, it's the 12v regulator in the PSU.

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#18 towmater OFFLINE  

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Posted Tue Oct 31, 2017 9:30 PM

I'd think it might help, as you'd be bypassing anything in the console that uses anything other than 5V? I guess it is a matter of how much you want to spend, though Console 5's five-volt mod kit is under $15.

 

At that point, an iPad charger could act as your PSU, offering more current than the old brick.


Edited by towmater, Tue Oct 31, 2017 9:33 PM.


#19 shabazz18 OFFLINE  

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Posted Tue Oct 31, 2017 9:48 PM

I'd think it might help, as you'd be bypassing anything in the console that uses anything other than 5V? I guess it is a matter of how much you want to spend, though Console 5's five-volt mod kit is under $15.
 
At that point, an iPad charger could act as your PSU, offering more current than the old brick.

Fair enough, just seems like a very convoluted solution to a 3 solder point problem.

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Edited by shabazz18, Tue Oct 31, 2017 9:49 PM.


#20 Bmack36 ONLINE  

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Posted Tue Oct 31, 2017 10:23 PM

The 5V mod is not actually a full 5V mod. It does reduce the VRAM to only using 5V which is helpful, but the system still needs 12V for the video output. The only current way to only use only 5V is to use the F18a.


Edited by Bmack36, Tue Oct 31, 2017 10:24 PM.


#21 rassafrassa OFFLINE  

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Posted Tue Oct 31, 2017 10:41 PM

thank you! ebay 'tested working' strikes again



#22 towmater OFFLINE  

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Posted Tue Oct 31, 2017 10:42 PM

Though, correct me if I am incorrect, only if one is using the RF modulator instead of composite. Is anyone still doing that? 



#23 shabazz18 OFFLINE  

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Posted Tue Oct 31, 2017 10:43 PM

Though, correct me if I am incorrect, only if one is using the RF modulator instead of composite. Is anyone still doing that? 

Me.

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#24 towmater OFFLINE  

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Posted Tue Oct 31, 2017 10:45 PM

You are truly retro sir, I salute you.







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