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What is this witchcraft? Heresy! 2600 switching power supply modification


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#51 -^CrožBow^- OFFLINE  

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Posted Mon Mar 20, 2017 5:24 PM

Got them in today's mail...HOLY CRAP they are Tiny?! They are actually smaller than a standard 7805 in that they are only maybe 3/4 the height and just a hair wider and only a hair thicker as well. So yeah, these should fit incredibly well in all applications. These have to be even smaller than the other DC-DC buck converters that were listed from Oki..etc. I will put two of them into my Genesis tonight and post results.

 

Also received my Kill-a-Watt reader in the mail today too, so hopefully I can get some initial readings on energy use. Not sure if the wall warts will alter or keep the same readings since it will be the one drawing the power. Also my Genesis doesn't normally use a sega adapter. I actually have one Golden.Ax's converted GC power supplies driving my Genesis/Sega CD/32x combo. I believe those are switching type power supplies already so yeah... 

 

But that power system is all buried literally behind my console display so I'm not taking everything out to measure it. I will only be able to measure just the Genesis from a stock sega brick.


Edited by -^CrožBow^-, Mon Mar 20, 2017 5:26 PM.


#52 Osgeld OFFLINE  

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Posted Mon Mar 20, 2017 6:22 PM

I dont think a kill-a-watt is going to show a whole bunch, the stock 7805 doesnt consume any meaningful amount of power, its all in the wall wart and the system consumption, what will be interesting to see if what interference you can see on screen 

 

smps's by their vary nature radiate radio noise, so while it may have a nice filter system to keep noise low on the output power, it is still a very low powered ultra tiny radio transmitter ... whether it effects anything or not depends on its internal switching frequency/ harmonics and internal shielding  ..ie if its switching at I dunno 500khz and its got a 2db harmonic spike in the low mhz range it might show up as effects on a composite video signal, or higher frequencies in the RF signal that dont really effect the base signal or whatever combination of both 

 

of couse the downside to linear regulator is, as we all know heat.. now with some very simple filtering you can make those little buggers output just about totally flat output and you can easily get darn near an amp out of them, even in the 80+ % range

 

course game consoles and toys dont do any of that, heck most of them wont spent a single penny to put a diode in place for simple reverse protection, so its not really the regulator's fault ... its just low cost design, and lets be real here, there's a metric ton of them that have been running since the 70's with no problem 


Edited by Osgeld, Mon Mar 20, 2017 6:26 PM.


#53 -^CrožBow^- OFFLINE  

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Posted Tue Mar 21, 2017 9:17 AM

Okay...so I installed two of the Traco buck converters into my genesis last night. However, I ended up taking them back out...here is why:

 

So first the good -

 

Standard stock supply was showing a constant 20va rating while in use overall draw according to the Kill-A-Watt.

The Power Factor indication was showing a steady .67. My understanding is that you want this closer to 1.0 I believe?

It was showing a usage of 16.8 watts while powered on and running Lightening Force in demo/attract mode.

Actual volts from the adapter was showing it was pulling in a steady 13.9 from the AC directly.

 

With the Traco converters installed I got these readings -

 

16.5 constant overall VA draw

Power Factor was worse showing .51 constant reading. Again I've read you ideally want this closer to 1.0.

It was only using 6.8watts of power...yeap... much less watts being consumed to operate.

Actual voltage being pulled from the AC to the stock adapter was only 8.9. 

 

So with the exception of the Power Factor rating, it would appear that running a set of these in a genesis with a stock power supply will still be quite the improvement in overall power usage and efficiency.

 

Now for the bad...

 

So... the main issue and it was enough to make me put both of the 7805s back in was much louder and whining noise on the audio. Lightening Force (Thunder Force IV) was more obvious and I really couldn't handle it. Additionally, I would also hear a weird rhythmic ticking in the audio line during quiet or silence in the game. And it wasn't a subtle ticking either...very audible and easily picked up. This doesn't happen with the 7805s installed.

 

The other issue and I'm not sure if it related to the Traco converters or not, is that while TF4 played well enough, I was having more issues than I usually do with Sonic 3 just resetting itself randomly within a few minutes of starting a game. This was made worst with Sonic and Knuckles also rebooting itself constantly within about 60sec of starting a game. If you just left Sonic and Knuckles on long enough, it would eventually start to reboot just after the sega logo or right after displaying the title screen logo. With the 7805s in place, this doesn't happen.

 

That said...I have noticed that I can't get Sonic3 and Sonic And Knuckles attached to work on my Genesis at all. It will go through frequently reboots as well, and show corrupted graphics...etc. but only with them docked. Played separately they are fine. This is my test bed genesis and has seen a lot of mods done to it over the years...so it could just..be...tired. It has been recapped as of about 2 years ago so that shouldn't be an issue. But it does appear that the Traco converters on a Genesis at least do work for the most part, but present some very audible noise and ticking in the audio and might have issues with some of the more complex games. One game I didn't try out now that I think about it, is Virtua Racing and I likely should have. I also didn't test with the 32x attached.

 

Honestly with the increased whine in the line level audio and ticks...I just didn't see a point to continue on.

 

However, I can tell you that the s-video picture quality was completely unaffected by the Traco converters and they do run much much cooler. You can touch them easily and they only get warm. But I did notice the one closed to the power connection gets more warm to low level hot as compared to the one closer to the YM2612 location.

 

So...those are the results. Less power required and consumed so it does appear to be much more efficient even with a stock power supply. And I assume it would improve even more using a switching power supply. In fact the Kill-A-Watt estimated that running my Genesis with the Traco converters would only cost me about $2 a month if left on constantly... then again my power company rate is roughtly $.13 1/2 cents per kilowatt right now which, isn't a bad rate to begin with.

 

Now I realize this thread started off talking about using these in a 2600 and for that I'm sure these would be fine to use on most of the other 8-bit systems. I will still see about installing one into my 7800 and possibly changing out the two on the 5200 as well to see if there is any audible line noise or video interference. Again on the Genesis the s-video was not affected by these at all. I did not test composite but would be able to on the 5200 at least when I install it into that. My 7800 has Magic Knight's s-video kit installed and there isn't any composite for that so it is s-video only for that console. 


Edited by -^CrožBow^-, Tue Mar 21, 2017 9:25 AM.


#54 mojoatomic OFFLINE  

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Posted Tue Mar 21, 2017 9:59 AM

Interesting results. I think it's important to note that RF, AV and s-video will all give potentially different results as to output quality. RF output on the 2600 is in fact cleaner with the Traco's, but that's all I tried. I think it would be interesting to put high and low pass caps on the Traco output and see what your results on the Genesis are. 

 

I have also been experimenting with switching power supplies on the 2600, with good results while using Traco's. Horrible (predictably, I know) without. 

 

There is a tremendous amount of room for improvement on the 2600's as far as filtering, as their filtering is absolutely terrible :-), yet still they work, and have worked for many tears. Atari was so cheap in this area - they did the absolute minimum. Still, for a few pennies in parts, it's AMAZING what you can do. 

 

I've got a 2600 that I've been experimenting with, if there's interest I can post results and video. Of note - I've done nothing to it that couldn't be undone... but I've modded it to pieces. I think you could put a blender on top of it and it wouldn't affect the RF :-) 



#55 Kosmic Stardust ONLINE  

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Posted Tue Mar 21, 2017 10:18 AM

Okay...so I installed two of the Traco buck converters into my genesis last night. However, I ended up taking them back out...here is why:
 
So first the good -
 
Standard stock supply was showing a constant 20va rating while in use overall draw according to the Kill-A-Watt.
The Power Factor indication was showing a steady .67. My understanding is that you want this closer to 1.0 I believe?
It was showing a usage of 16.8 watts while powered on and running Lightening Force in demo/attract mode.
Actual volts from the adapter was showing it was pulling in a steady 13.9 from the AC directly.
 
With the Traco converters installed I got these readings -
 
16.5 constant overall VA draw
Power Factor was worse showing .51 constant reading. Again I've read you ideally want this closer to 1.0.
It was only using 6.8watts of power...yeap... much less watts being consumed to operate.
Actual voltage being pulled from the AC to the stock adapter was only 8.9. 
 
So with the exception of the Power Factor rating, it would appear that running a set of these in a genesis with a stock power supply will still be quite the improvement in overall power usage and efficiency.
 
Now for the bad...
 
So... the main issue and it was enough to make me put both of the 7805s back in was much louder and whining noise on the audio. Lightening Force (Thunder Force IV) was more obvious and I really couldn't handle it. Additionally, I would also hear a weird rhythmic ticking in the audio line during quiet or silence in the game. And it wasn't a subtle ticking either...very audible and easily picked up. This doesn't happen with the 7805s installed.
 
The other issue and I'm not sure if it related to the Traco converters or not, is that while TF4 played well enough, I was having more issues than I usually do with Sonic 3 just resetting itself randomly within a few minutes of starting a game. This was made worst with Sonic and Knuckles also rebooting itself constantly within about 60sec of starting a game. If you just left Sonic and Knuckles on long enough, it would eventually start to reboot just after the sega logo or right after displaying the title screen logo. With the 7805s in place, this doesn't happen.
 
That said...I have noticed that I can't get Sonic3 and Sonic And Knuckles attached to work on my Genesis at all. It will go through frequently reboots as well, and show corrupted graphics...etc. but only with them docked. Played separately they are fine. This is my test bed genesis and has seen a lot of mods done to it over the years...so it could just..be...tired. It has been recapped as of about 2 years ago so that shouldn't be an issue. But it does appear that the Traco converters on a Genesis at least do work for the most part, but present some very audible noise and ticking in the audio and might have issues with some of the more complex games. One game I didn't try out now that I think about it, is Virtua Racing and I likely should have. I also didn't test with the 32x attached.
 
Honestly with the increased whine in the line level audio and ticks...I just didn't see a point to continue on.
 
However, I can tell you that the s-video picture quality was completely unaffected by the Traco converters and they do run much much cooler. You can touch them easily and they only get warm. But I did notice the one closed to the power connection gets more warm to low level hot as compared to the one closer to the YM2612 location.
 
So...those are the results. Less power required and consumed so it does appear to be much more efficient even with a stock power supply. And I assume it would improve even more using a switching power supply. In fact the Kill-A-Watt estimated that running my Genesis with the Traco converters would only cost me about $2 a month if left on constantly... then again my power company rate is roughtly $.13 1/2 cents per kilowatt right now which, isn't a bad rate to begin with.
 
Now I realize this thread started off talking about using these in a 2600 and for that I'm sure these would be fine to use on most of the other 8-bit systems. I will still see about installing one into my 7800 and possibly changing out the two on the 5200 as well to see if there is any audible line noise or video interference. Again on the Genesis the s-video was not affected by these at all. I did not test composite but would be able to on the 5200 at least when I install it into that. My 7800 has Magic Knight's s-video kit installed and there isn't any composite for that so it is s-video only for that console. 

So the buck supplies do in fact emit more noise when installed versus the stock 7805. If I have to add a bunch of filter caps and junk to the circuit to get it clean, it would defeat the purpose of the upgrade. Honestly the cooler operation is desirable, but not at the expense of excess noise. Have anyone tested these regulators through a "dummy" load such as a resistor or lamp using a scope? I'm curious what the effect would be and the frequency of the ripple, whether it is audible or closer to ntsc frequencies? All my systems are super clean A/V wise except the VCS, and I suspect it's RF related on the Atari. I'm tempted to add an isolation block to the internal coax, as the choke isn't quite cutting it. Could also be cheap coax between the F coupler I installed and the TV. The interference pattern changes when I jiggle the cable.

#56 mojoatomic OFFLINE  

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Posted Tue Mar 21, 2017 10:30 AM

So the buck supplies do in fact emit more noise when installed versus the stock 7805. If I have to add a bunch of filter caps and junk to the circuit to get it clean, it would defeat the purpose of the upgrade. Honestly the cooler operation is desirable, but not at the expense of excess noise. Have anyone tested these regulators through a "dummy" load such as a resistor or lamp using a scope? I'm curious what the effect would be and the frequency of the ripple, whether it is audible or closer to ntsc frequencies? All my systems are super clean A/V wise except the VCS, and I suspect it's RF related on the Atari. I'm tempted to add an isolation block to the internal coax, as the choke isn't quite cutting it. Could also be cheap coax between the F coupler I installed and the TV. The interference pattern changes when I jiggle the cable.

 

You definitely have a bad cable or poor connection / bad component connected to the cable. Also, the choke only helps keeping the cable from acting line an antenna - if the RF is injected and amplified before it gets there, it won't be able to help. 


Edited by mojoatomic, Tue Mar 21, 2017 10:31 AM.


#57 -^CrožBow^- OFFLINE  

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Posted Tue Mar 21, 2017 11:01 AM

So the buck supplies do in fact emit more noise when installed versus the stock 7805. If I have to add a bunch of filter caps and junk to the circuit to get it clean, it would defeat the purpose of the upgrade. Honestly the cooler operation is desirable, but not at the expense of excess noise. Have anyone tested these regulators through a "dummy" load such as a resistor or lamp using a scope? I'm curious what the effect would be and the frequency of the ripple, whether it is audible or closer to ntsc frequencies? All my systems are super clean A/V wise except the VCS, and I suspect it's RF related on the Atari. I'm tempted to add an isolation block to the internal coax, as the choke isn't quite cutting it. Could also be cheap coax between the F coupler I installed and the TV. The interference pattern changes when I jiggle the cable.

 

They definitely run MUCH cooler. I even left them standing up a tad to give airflow all around them, but that isn't needed. I could have just soldered them totally flat against the PCB. If you were to use these in a 2600jr, you might have to add small wires to the leads off these converters so you could hot glue them down flat against the PCB. They might stand too tall otherwise. But I don't feel like cracking open my Jr. to check it right now.

 

But yes the much increased line level noise and especially the occasional ticks that were going off was really distracting. Obviously when music was playing on the genesis this noise isn't heard or noticed, but as soon as you click on the power...there it is.

 

I'm going to put one into the 7800 next as that is my next console that just gets crazy hot! I even have a much newer and more efficient 7805 amp model installed, but still amazingly hot it gets. I do have the 7800 AV modded so hopefully the noise isn't there but if it is..I will post it here.


Edited by -^CrožBow^-, Tue Mar 21, 2017 11:04 AM.


#58 -^CrožBow^- OFFLINE  

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Posted Tue Mar 21, 2017 11:07 AM

Interesting results. I think it's important to note that RF, AV and s-video will all give potentially different results as to output quality. RF output on the 2600 is in fact cleaner with the Traco's, but that's all I tried. I think it would be interesting to put high and low pass caps on the Traco output and see what your results on the Genesis are. 

 

I have also been experimenting with switching power supplies on the 2600, with good results while using Traco's. Horrible (predictably, I know) without. 

 

There is a tremendous amount of room for improvement on the 2600's as far as filtering, as their filtering is absolutely terrible :-), yet still they work, and have worked for many tears. Atari was so cheap in this area - they did the absolute minimum. Still, for a few pennies in parts, it's AMAZING what you can do. 

 

I've got a 2600 that I've been experimenting with, if there's interest I can post results and video. Of note - I've done nothing to it that couldn't be undone... but I've modded it to pieces. I think you could put a blender on top of it and it wouldn't affect the RF :-) 

 

I've a small stash of caps...have any recommended values to try? And I assume we are only talking about installing them inline off the +5 output right? So..the positive lead on the caps should all point towards the +5 connection?

 

I'm not an engineer so do excuse my ignorance in asking the above. Also I would assume any voltage cap of at least +16 and up is good right?



#59 mojoatomic OFFLINE  

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Posted Tue Mar 21, 2017 11:45 AM

I do have a few suggestions :-) On the 2600

 

Replace C242 with a .22, C243 unchanged, C241 - place 10uf in parallel (observing polarity), C240 unchanged, C239 - place a 10uf in parallel with it (observing polarity) - doesn't matter if the 10uf caps go on the front or back of the board, just keep the leads short. 

 

I need to run this output through a signal analyzer and plot what ferrite bead would be best to suppress noise. This would be to replace the ferrite bead at L204. It will be different for the 7805 and the Traco. 

 

Yes, 16v or up is fine 


Edited by mojoatomic, Tue Mar 21, 2017 11:48 AM.





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