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Nateo

Console5 AV mod weirdness

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I recently bought and installed a ColecoVision AV mod kit from Console5. It's a pretty easy solder job, everything on my end soldering has been hunky dory. No accidental bridgings, no cold solder joints, pretty as a picture. Turn it on, looks fine to start, but then slowly the picture dims until a scrolling, dim, fuzzy image.

I suspect something to be wrong with maybe my power supply, but just to be sure, I hook it up using the normal RF and turn it on. I still had it on the composite input, and lo and behold, I get a beautiful, stable image! I unplugged the RF cable and immediately the picture turned to a dim mess. Plugged it back in, composite video looked great.

What the hell is going on here?

(Below is the wiring diagram for this mod)

cv-composite-pcb-connections.jpg

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Here's the pictures of my install.

The multimeter readings for the pinouts are:

+12v - 11.6v

+5v - 4.66v

-5v - (-)5.18v

 

20200731_154941.jpg

20200731_154949.jpg

20200731_154957.jpg

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Posted (edited)

The +12 and +5 are a little bit on the low side.  With the console on, what is the +12 voltage on the RF box?

Edited by Ruggers Customs
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Where are you taking those voltage readings from?  Are they when the unit is powered on?

 

I would suggest hooking up the composite to your display and then continuously monitoring the +12V voltage where you soldered the red wire connects to the RF PCB.  Turn on your CV and watch the 12V reading on your multimeter as your display dims.

 

I agree with Ruggers - those voltages look on the low side.  It could just be that the extra power draw from the video mod is simply too much for your power supply.

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1 minute ago, Ikrananka said:

Where are you taking those voltage readings from?  Are they when the unit is powered on?

 

I would suggest hooking up the composite to your display and then continuously monitoring the +12V voltage where you soldered the red wire connects to the RF PCB.  Turn on your CV and watch the 12V reading on your multimeter as your display dims.

 

I agree with Ruggers - those voltages look on the low side.  It could just be that the extra power draw from the video mod is simply too much for your power supply.

I took the multimeter readings directly from the back of the power socket. Just checked the points on the RF board, and that also reads 11.61v. They way the screen dims and then just turns into a gray scrolling mess sure seems like power is fading. Probably time to pick up a COLUSB then eh?

But I still gotta know... why does it work like a charm when the RF is plugged in too? Is it getting extra juice from the TV somehow?

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I had a customer a couple of months back that had a similar issue and it turned out the be his power supply.  A quick power supply rebuild and good as new.  Instead of the Colusb, I would look into HDTV's power supply on eBay.  I haven't used one yet but I've heard pretty good things about it.

 

https://www.ebay.com/itm/28-5-watt-ColecoVision-compatible-power-supply-The-best-quality-PS-every-made/114258620533?hash=item1a9a583075:g:EFUAAOSw6ohe5cu2

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5 minutes ago, Ruggers Customs said:

I had a customer a couple of months back that had a similar issue and it turned out the be his power supply.  A quick power supply rebuild and good as new.  Instead of the Colusb, I would look into HDTV's power supply on eBay.  I haven't used one yet but I've heard pretty good things about it.

 

https://www.ebay.com/itm/28-5-watt-ColecoVision-compatible-power-supply-The-best-quality-PS-every-made/114258620533?hash=item1a9a583075:g:EFUAAOSw6ohe5cu2

Thanks! I'll look into that. Hoping that this'll solve the issue. I REALLY don't want to have to replace a chip if I can avoid it!

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Posted (edited)
25 minutes ago, Nateo said:

I took the multimeter readings directly from the back of the power socket. Just checked the points on the RF board, and that also reads 11.61v. They way the screen dims and then just turns into a gray scrolling mess sure seems like power is fading. Probably time to pick up a COLUSB then eh?

But I still gotta know... why does it work like a charm when the RF is plugged in too? Is it getting extra juice from the TV somehow?

As Ruggers said, I'd recommend a new power supply anyway, 11.6V is definitely too low.

 

Did you see the 11.6V reading drop as the screen dimmed - that would be a 100% giveaway that it's the power supply.  The drop might not be that much so you'll need to watch the multimeter carefully.

 

I have no definite idea why it works fine with the RF plugged in but I'm sure it's not getting juice from your TV.  Probably something to do with the power draw of the LM1889 video modulator and how it changes when RF is connected and disconnected.  If you monitor the +12V point I mentioned above while connecting and disconnecting the RF cable you'll see how the voltage reacts.

Edited by Ikrananka
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2 hours ago, Ruggers Customs said:

I had a customer a couple of months back that had a similar issue and it turned out the be his power supply.  A quick power supply rebuild and good as new.  Instead of the Colusb, I would look into HDTV's power supply on eBay.  I haven't used one yet but I've heard pretty good things about it.

 

https://www.ebay.com/itm/28-5-watt-ColecoVision-compatible-power-supply-The-best-quality-PS-every-made/114258620533?hash=item1a9a583075:g:EFUAAOSw6ohe5cu2

This power supply is awesome. It doesn't get hot and works as a perfect modern replacement. Love mine!

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Posted (edited)

I don't know. If it works with RF connected, maybe it's an impedance or a grounding problem. Both of these will change with something connected to RF vs. unconnected.

 

Also, what kind of output connector is that?

Edited by R.Cade

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5 hours ago, Ruggers Customs said:

I had a customer a couple of months back that had a similar issue and it turned out the be his power supply.  A quick power supply rebuild and good as new.  Instead of the Colusb, I would look into HDTV's power supply on eBay.  I haven't used one yet but I've heard pretty good things about it.

 

https://www.ebay.com/itm/28-5-watt-ColecoVision-compatible-power-supply-The-best-quality-PS-every-made/114258620533?hash=item1a9a583075:g:EFUAAOSw6ohe5cu2

I will second this I have had mine for about 2 months and never gets hot and works great. I use it on my test bench when I am repairing colecovisions. My first choice is always an original power brick but this is a great second choice. Cheers.

 

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Posted (edited)
1 hour ago, R.Cade said:

I don't know. If it works with RF connected, maybe it's an impedance or a grounding problem. Both of these will change with something connected to RF vs. unconnected.

 

Also, what kind of output connector is that?

I'm just using an 1/8in stereo connector. The right channel is video, the left is the audio. I'm connecting using an 1/8in stereo to RCA cable.

 

EDIT: @R.Cade, do you think it might be worth a try to tie the ground connections to another ground spot on the board?

Edited by Nateo

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8 minutes ago, R.Cade said:

That mod looks like an SMT version of this (http://www.retrofixes.com/2015/06/colecovision-svideo-or-composite.html).

 

However, it uses a different ground point. 

 

I would give it a try. 

 

All the av mods use the same circuit that's been around forever.  That's actually Mobius Strip Techs board but built by me and sold through console 5.  Far better than what's out there now.  That ground point that C5 has listed is a dead short to all other ground points on the board so it's more than sufficient.

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So what's wrong with it? You really think 11.6v is not enough? You are going to have him buy a new power supply for a CV that works fine without the mod, but also works fine with the RF connected?

 

 

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Posted (edited)
20 minutes ago, R.Cade said:

So what's wrong with it? You really think 11.6v is not enough? You are going to have him buy a new power supply for a CV that works fine without the mod, but also works fine with the RF connected?

 

 

There's nothing wrong with the AV board if that's what you're getting at.  I'm also not telling anyone to do anything but merely suggesting.  His mod board is wired up correctly from his pictures.  He hasn't done anything else to the mobo so things like backward installed caps can be ruled out.  He said that his voltages were 11.6v and 4.6v which coming out of an original supply not under load and from the points on the board are lower than normal.  Generally an av modded coleco working then slowly cutting out with lower than normal voltage readings suggest a failing power supply which is fairly common. Which is I suggested looking more closely at the power supply or switch or rear power jack connector or all three.

 

Why av "suddenly works" when the rf cord is plugged in, well I've never encountered that so I don't know.

 

If by some odd chance that there is something wrong with the AV board then don't you worry, I'll take care of it at my expense.  Ask any of my customers here, they'll tell you I have no problem doing that.

Edited by Ruggers Customs
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Posted (edited)

@Nateo DM your shipping address and I'll send you another board just to you can rule the board out before purchasing another power supply.

Edited by Ruggers Customs

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5 hours ago, ChildOfCv said:

What are the voltages at the AV board?

And question 2:  Does the RF connector need to be plugged in on both sides, or is it just sufficient to have something plugged into the CV?  If the latter, then it may be a mechanical stress issue.

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5 hours ago, Ruggers Customs said:

There's nothing wrong with the AV board if that's what you're getting at.  I'm also not telling anyone to do anything but merely suggesting.  His mod board is wired up correctly from his pictures.  He hasn't done anything else to the mobo so things like backward installed caps can be ruled out.  He said that his voltages were 11.6v and 4.6v which coming out of an original supply not under load and from the points on the board are lower than normal.  Generally an av modded coleco working then slowly cutting out with lower than normal voltage readings suggest a failing power supply which is fairly common. Which is I suggested looking more closely at the power supply or switch or rear power jack connector or all three.

 

Why av "suddenly works" when the rf cord is plugged in, well I've never encountered that so I don't know.

 

If by some odd chance that there is something wrong with the AV board then don't you worry, I'll take care of it at my expense.  Ask any of my customers here, they'll tell you I have no problem doing that.

I have used probably 10 or more of these exact same boards and never had a problem with any of them. I do lots of AV mods and I doubt it is the board causing it to do what is being described here.

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Posted (edited)

I wasn't suggesting it was the mod board- I don't know what it is. I was only saying to look at other options closely before getting a new power supply. My comments probably came off as attacking someone and that is my fault - I am sorry. Watching the voltages while it's happening is a great thing to check. It seems like that board would only put a tiny load on the power supply.

 

I have seen something similiar once when I modded a Coleco, but the circumstances were very different. It was a simple transistor mod and I think I used the 12v line instead of 5v, so it would very quickly overheat. That's not the case here, I doubt. It certainly wouldn't explain the RF out variable. 

 

As I mentioned, the only thing that should change when you plug RF in is the grounding and impedance. Someone else mentioned physical stresss and that's also possible. Just for kicks, have you tried another television?

Edited by R.Cade

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12 hours ago, Ruggers Customs said:

@Nateo DM your shipping address and I'll send you another board just to you can rule the board out before purchasing another power supply.

No worries, I trust the build quality of the board :) I fully believe the problem lies either with something on the main circuit board or the power supply itself, and the power supply seems to me to be the most plausible culprit. I'll still try seeing how good the ground connections are on the board and try a different TV before making a purchase.

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Posted (edited)

Welp, I figured out my problem. IT WAS THE FRIGGING AV CABLE I WAS USING! I noticed that I broke the ground connection from 1/8in jack, and when it was disconnected, I got the same kind of fun, gray scrolling picture. That immediately led me to the conclusion that the reason I was getting that wonky picture was due to a poor ground connection. I tried another 1/8in to RCA cable, and lo and behold, a perfect signal. 

Come to think of it, I had tried to use that faulty cable with a cassette deck I was repairing, and thought that something was wrong with it due to extra buzzing noise I heard. I'll bet that was all due to a poor ground connection.

Thanks to everyone who helped out. And @Ruggers Customs, I'll probably just grab that new PSU anyways, since I don't want any further harm to come to my Coleco.

Edited by Nateo
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