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

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Well...the Intellivision numbers are in, but not that impressive I'm sad to say....

 

Off the kill-a-watt with the original 78xx series regulators installed we get:

 

Running time : 2:25min

AC Line voltage = 122.8

PF = .81

Va = 19.8

Watts = 16

Amps = .16

 

With the DC/DC converters in place we read:

 

Running time : 3:15min

AC line voltage = 123

Pf = .78

Va = 16.2

Watts = 12.8

Amps = .13

 

The DC/DC converters do actually get pretty warm installed in the Intellivision. They aren't too hot to the touch or anything, but there is definite heat within them that I wasn't getting from other consoles I've used them in.

 

And in summary, if I were running the Intellivision 24/7 365 days a year with the old regulators, it would cost me $18 USD a year to operate. With the DC/DC converters it drops to $14.40 a year. So far the Intellivision has shown the least amount of change between the 78xx regulators and DC/DC converters. There is a difference in power consumption, cost to operate, and a little less heat, but when you bundle that the converters cost $7 each it would take just under 4 years of constant operation to make up the difference in costs. So...not sure it was worth it on the Intellivision overall. But they are installed and I will keep them in there. No noticeable interference either as I suspected due to the distance of these converters compared to the audio and video circuits in the system.

Edited by -^Cro§Bow^-

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keep in mind that heat is not a simplistic analog thing, complexity + hot = eh

 

vs a 7805 can run at 120c for 40 years non stop, and it wont be heat that kills it (its power spikes and crap input filtering that kills them, you can take a brand new one and kill it in 1 second sending it an AC signal)

 

there's trade-off's, and different situations

 

on systems that suck < 500ma at 9-10 volt input, with ok smoothing, I hardly see the point in replacing a 25 cent part with a 6 dollar part + postage, that covers most of the consoles, with exception to the 7800 which gets nasty hot even with a large heat sink as its doing double duty

Edited by Osgeld

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I hardly see the point in replacing a 25 cent part with a 6 dollar part + postage, that covers most of the consoles, with exception to the 7800 which gets nasty hot even with a large heat sink as its doing double duty

 

 

Giggles, mostly.

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I just ordered 5V and 12V Traco converters for my 1050 drive. I couldn't care less about saving a few cents on power usage. I'm just tired of pulling my floppy disks out feeling like they were in a toaster oven.

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I just ordered 5V and 12V Traco converters for my 1050 drive. I couldn't care less about saving a few cents on power usage. I'm just tired of pulling my floppy disks out feeling like they were in a toaster oven.

I'm with you on this one and it was the primary reason I'm doing this is to reduce the heat. However, again on the Intelly, this isn't really helping because the transformer inside generates a ton of heat on its own, and there is more voltage and current going to these converters in the Intelly as opposed to the other consoles. I was measuring nearly 21 volts going to the +12 and about 10 going to the +5. The 10 on the +5 shouldn't really do much and it could be that because of the size (width) of the converters, they actually kinda touch each other in the Intelly. Could be heat transfer between the +12 to the +5 that causes them both to get much warmer than they do on other consoles. I still have 3 of the +5 and 1 of the +12 volt versions. Not sure what I will use them on at this point. One will likely go into my TurboDuo but I will have to use a genesis power supply for the testing since the actual turbo duo's brick is pretty inaccessible behind the console case in the game room.

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I'm with you on this one and it was the primary reason I'm doing this is to reduce the heat. However, again on the Intelly, this isn't really helping because the transformer inside generates a ton of heat on its own, and there is more voltage and current going to these converters in the Intelly as opposed to the other consoles. I was measuring nearly 21 volts going to the +12 and about 10 going to the +5. The 10 on the +5 shouldn't really do much and it could be that because of the size (width) of the converters, they actually kinda touch each other in the Intelly. Could be heat transfer between the +12 to the +5 that causes them both to get much warmer than they do on other consoles. I still have 3 of the +5 and 1 of the +12 volt versions. Not sure what I will use them on at this point. One will likely go into my TurboDuo but I will have to use a genesis power supply for the testing since the actual turbo duo's brick is pretty inaccessible behind the console case in the game room.

If they are getting hot then the current might be a bit high for the device.

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If they are getting hot then the current might be a bit high for the device.

 

Datasheets state they can take up to a 2.5amp input current? I can't imagine that the Intelly is sending that much current to the +12 and +5 lines. Though to be fair, I didn't measure the current before changing them out. And they don't get so hot that you can't touch them. They are just noticeably warmer as compared to how they are on the other consoles I've tested and used them on.

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Datasheets state they can take up to a 2.5amp input current? I can't imagine that the Intelly is sending that much current to the +12 and +5 lines. Though to be fair, I didn't measure the current before changing them out. And they don't get so hot that you can't touch them. They are just noticeably warmer as compared to how they are on the other consoles I've tested and used them on.

The primary limit for these devices is internal temperature. That is what will break it. If you can comfortably touch it then your not near that limit. If you getting the correct voltage out, then you haven't reached the current cutoff either, so you should be good.

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The primary limit for these devices is internal temperature. That is what will break it. If you can comfortably touch it then your not near that limit. If you getting the correct voltage out, then you haven't reached the current cutoff either, so you should be good.

Right, and I did leave it all up and running for well over 3 hours last night with the new DC/DC converters in place and it never cut out or any issues like that. Seemed to play rock solid. I was also testing using my LTO Flash just to make sure to have as much current draw as I could from everything in the system.

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Well...the Intellivision numbers are in, but not that impressive I'm sad to say....

 

Off the kill-a-watt with the original 78xx series regulators installed we get:

 

Running time : 2:25min

AC Line voltage = 122.8

PF = .81

Va = 19.8

Watts = 16

Amps = .16

 

With the DC/DC converters in place we read:

 

Running time : 3:15min

AC line voltage = 123

Pf = .78

Va = 16.2

Watts = 12.8

Amps = .13

 

The DC/DC converters do actually get pretty warm installed in the Intellivision. They aren't too hot to the touch or anything, but there is definite heat within them that I wasn't getting from other consoles I've used them in.

 

And in summary, if I were running the Intellivision 24/7 365 days a year with the old regulators, it would cost me $18 USD a year to operate. With the DC/DC converters it drops to $14.40 a year. So far the Intellivision has shown the least amount of change between the 78xx regulators and DC/DC converters. There is a difference in power consumption, cost to operate, and a little less heat, but when you bundle that the converters cost $7 each it would take just under 4 years of constant operation to make up the difference in costs. So...not sure it was worth it on the Intellivision overall. But they are installed and I will keep them in there. No noticeable interference either as I suspected due to the distance of these converters compared to the audio and video circuits in the system.

The power factor drops off because the transformer in the DC adapter acts as a large inductor when no load is present. It also has resistance so that factors into your electricity usage. I'm curious to see the statistics on the brick with the console off and no load (unplugged). I imagine the PF rating on the unloaded AC brick will be abysmal (closer to 1 = better). You may also find that those old bricks will get warm even when nothing is plugged in. A modern switching transformer would run much cooler I think. The one I have is a 9V wallwart from RadioShack with like multiple tips spliced onto the end, stays fairly cool to the touch, much moreso than the vintage unregulated bricks, and it outputs a constant 10V whether loaded or not, where the vintage bricks tend to run a bit higher than the nameplate according to my multimeter. That can also contribute to heat dissipation on the old 7805 regulators, which pass the full current and sink the excess volts as heat.

 

Utilities are fairly cheap where I am from (Louisiana), but major appliances and central heating / AC are going to account for the bulk of your utility bill, followed closely behind by lighting (running high efficiency light bulbs helps, with compact florescent about 25% and LEDs consuming 10% the usage of a traditional Edison style lamp with tungsten filament). The wall warts are really just chump change in comparison, but if you are concerned, plug your game center into a power strip and switch it off when not in use.

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The power factor drops off because the transformer in the DC adapter acts as a large inductor when no load is present. It also has resistance so that factors into your electricity usage. I'm curious to see the statistics on the brick with the console off and no load (unplugged). I imagine the PF rating on the unloaded AC brick will be abysmal (closer to 1 = better). You may also find that those old bricks will get warm even when nothing is plugged in. A modern switching transformer would run much cooler I think. The one I have is a 9V wallwart from RadioShack with like multiple tips spliced onto the end, stays fairly cool to the touch, much moreso than the vintage unregulated bricks, and it outputs a constant 10V whether loaded or not, where the vintage bricks tend to run a bit higher than the nameplate according to my multimeter. That can also contribute to heat dissipation on the old 7805 regulators, which pass the full current and sink the excess volts as heat.

 

Utilities are fairly cheap where I am from (Louisiana), but major appliances and central heating / AC are going to account for the bulk of your utility bill, followed closely behind by lighting (running high efficiency light bulbs helps, with compact florescent about 25% and LEDs consuming 10% the usage of a traditional Edison style lamp with tungsten filament). The wall warts are really just chump change in comparison, but if you are concerned, plug your game center into a power strip and switch it off when not in use.

 

Wow..okay so I guess I need to explain a few things here...

 

First the Intellivision older models do NOT have a wall wart. In stead they contain a multiple voltage isolation transformer inside them that provides the various voltage feeds that eventually make it to the regulation section on the power supply board. But power factor on the Intelly is actually not nearly as great as the PF drop off in the other consoles I've installed these on so that wasn't news to me. Again...this is being done more to reduce the heat within the consoles to thereby increase the longevity of the components as a whole in the systems.

 

Second you are correct in that using a switching power supply transformer instead of the usual wall wart is also just as efficient. I believe there are videos on youtube of people do exactly that with comparison measures, and also pairing them up with these small switching regulators as well for even more efficiency.

 

I'm not really concerned with my electric bill in regards to all of my consoles and this is why:

Everything in the game room is already basically on multiple power strips that eventually end up being plugged into 1 larger smart power strip. I say smart because they are electrically switched off until the device plugged into the master outlet is powered on. When it is, the power strip powers on the rest of the outlets. I've about a half dozen of these smart strips in my home. The entire game room is powered from them, the TV and surround system in the back living and bedroom are powered this way, both my computer and my wife's computer use them...etc. They have been amazing at reducing electricity usage since they essentially remove all vampire usage from everything plugged in. Only the device attached to the master outlet remains in standby.

 

At this point in time my home now contains about 70% LED lighting throughout. This includes the large floodlights I have outside as security lighting. There are still several fixtures where CFLs or even old school fluorescent is still being used. But the main lights that are on all the time or used most are LED at this point.

 

I'd like to think I've done a pretty decent job making my old 1965 built home energy efficient. In fact it is a 2 story home with two AC units and 2 gas furnaces. That being said, in the winter time my electric bill averages about $55 a month. In the summer it is more because of the AC units, but has never gone above $175 and since installing the programmable thermostats two years ago, the highest the bill got this past summer was about $155. Granted this will fluctuate with the weather but we have pretty mild winters where I live but can have some brutal and humid summers too. My electric company has a scale they use for how efficient your home is based on your KW usage over time as compared with other homes of similar size and type in your city. They use a scale from 1 to 10...1 being the most poorly efficient to 10 being the most efficient. My house is rated at a 9 on that scale. So I would hope that I'm doing something right and even these little guys help in the long run to contribute even more to that.

 

So again, I'm not doing all of this really to save on my power bill because the consoles wall warts..etc aren't even powered on until I turn on the AV receiver that acts as the master device. I did all of this, because I was curious, because I can, and because as my hands become less and less stable to do soldering work, I would like to think these consoles will outlive me at this point.

 

But not everyone has a crazy setup like mine or can afford to make their house that efficient. For those, these simple tests I'm doing might be very interesting and provide something useful.

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I just ordered 5V and 12V Traco converters for my 1050 drive. I couldn't care less about saving a few cents on power usage. I'm just tired of pulling my floppy disks out feeling like they were in a toaster oven.

The experiment failed :( I installed the Traco 1A parts and the drive couldn't reliably read a disk. Lots of random errors. I checked the voltages and they were in spec. I don't have a lot of time to diagnose the problem so I put the old regulators back in and it works again. I might try again later when I have time to troubleshoot.

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The experiment failed :( I installed the Traco 1A parts and the drive couldn't reliably read a disk. Lots of random errors. I checked the voltages and they were in spec. I don't have a lot of time to diagnose the problem so I put the old regulators back in and it works again. I might try again later when I have time to troubleshoot.

That sucks. Inadequate filtering? It's like the old 7805, etc kind of filtered the supply for you by clipping to the desired voltage. How bad really are the HF transients on these things?

 

Someone needs to hook up a resistive load, about 10 ohms should do (500mA @ 5V) to the output of one of these converters. Hook a scope up to the resistor terminals and see if any nasties are present in the signal and what period and magnitude said abberations have. Rinse and repeat with a 7805. That would rule out any signal fluctuations from digital components. I would imagine the higher the load, the more transients would be present.

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That sucks. Inadequate filtering? It's like the old 7805, etc kind of filtered the supply for you by clipping to the desired voltage. How bad really are the HF transients on these things?

 

Someone needs to hook up a resistive load, about 10 ohms should do (500mA @ 5V) to the output of one of these converters. Hook a scope up to the resistor terminals and see if any nasties are present in the signal and what period and magnitude said abberations have. Rinse and repeat with a 7805. That would rule out any signal fluctuations from digital components. I would imagine the higher the load, the more transients would be present.

 

Crap I just made a digikey order this week, I should have thrown one on there, I have a scope and my work has a RF spectrum analyzer, that would be amusing for science of atarweee

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Wanted to update that I've now also installed two of these to replace the 7805s in my TurboDuo. It works just fine and I took measurements of the power usage. However, while the CD audio is completely unaffected, I did notice quite a bit of hiss and noise when I fired up Air Zonk from my TurboED. I didn't notice it while the game playing but it was immediately noticeable once the title screen came up. However, I didn't put the 7805s back in. I may or may not...having decided because the power readings are pretty decent with the conversion and of course there is no heat inside the console now whereas those two 7805s in tandem next to each other were quite the space heater before.

 

Also I'm going to revisit the Genesis again because in looking over the Schems from another posts here on AA, I noticed something I hadn't before. The 7805s in the Genesis each essentially power half the system. So one is responsible for powering the 68k expansion ports and cart connector plus vdp and ram, while the other is primarily powering the audio circuits like the z80, 1034, 2612...etc and some of the video subsystems like the encoder and RF out. The point being...I wonder if I could get a hybrid solution wherein changing only the regulator that doesn't power the audio portion and thereby get some benefit of slight efficiency while not affecting the audio side and introducing the noise I heard before? Seems doable and easy enough to try right? Likely the same holds true of the turboduo as well, though I would suspect it has more to do with regulating the mainpcb and CD interface system. Have to check schems to know.

 

If nothing else I have exactly 1 left of each dc/dc converter and could just pop them into my Tandyvision one.

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^^Is there some reason why the Genesis has two isolated 5V power planes? Noise isolation or simply two low power regulators was cheaper than one high power? What if someone simply used a more powerful regulator and bridged them?

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if I had to guess its for noise, otherwise they would have put 2 in parallel and doubled the current of a single 5v rail

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Well.interesting there are a few points in the Genesis schem where it appears that voltage from both Vcc1 and Vcc2 which correlates to the two 7805s, are actually fed into a single IC in places. So in theory there are parts where they are essentially mixed. But yeah, one 7805 marked as Vcc1 provides the +5 to some stuff and the other marked Vcc2 to the rest of the components.

 

Also, I need to verify but I could have sworn that the va7 model 1 and all Genesis model 2s, only contain 1 7805 in them? Likely the move to cmos based ICs made this more doable. So noise could be part of it, but I bet it had more to do with power and current to all that was needed originally.

 

I believe the Genesis model 1 using two 7805c regulators. Those are 1.5amp output regulators. I have to double check that but if true then in theory one 7805c should be enough since the power supplies themselves could only produce a 1.2 amp max current for the beefiest model PS they released. (Looking at the CDX and X'eye).

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1.5 amps with a 9 volt input would put a 7805c at over 300c (without a heatsink)

Edited by Osgeld

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1.5 amps with a 9 volt input would put a 7805c at over 300c (without a heatsink)

 

Which, is why there is such a large chunk of metal in there that the two 7805s are attached to and why I was trying to eliminate them from my now heavily modded HDG va2 genesis LOL!

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A switcher would be a good choice for a situation like that, but dont be surprised if it does require more filtering

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A switcher would be a good choice for a situation like that, but dont be surprised if it does require more filtering

OH I know it would! I already put two of these switchers in my Genesis and the noise on the audio was immediately noticeable! It also did other odd things like strange pops and a ticking sound as well. That is why I tossed the 7805s back into it. But I wouldn't be opposed to just replacing one of them out to see if it helps any. Might do that tonight...

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if I had to guess its for noise, otherwise they would have put 2 in parallel and doubled the current of a single 5v rail

Putting two regulators in parallel is not a good idea. They will fight each other because their output settings won't match exactly due to component tolerances. The one with the higher setting will win and the other will switch off.

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Also, I need to verify but I could have sworn that the va7 model 1 and all Genesis model 2s, only contain 1 7805 in them? Likely the move to cmos based ICs made this more doable. So noise could be part of it, but I bet it had more to do with power and current to all that was needed originally.

Mine is a VA7 Model 1. 8)

 

Audio is quite good if you take if from the headphone jack instead of the line out or RF.

 

Putting two regulators in parallel is not a good idea. They will fight each other because their output settings won't match exactly due to component tolerances. The one with the higher setting will win and the other will switch off.

QTF.

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