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


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#26 Kosmic Stardust OFFLINE  

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Posted Tue Mar 14, 2017 3:33 AM

True drop in replacement.

 

Having said that - I would however change out the 40 year old caps as a prophylactic measure - have a look at the schematic, you'll see that 9v is pulled BEFORE it reaches the regulator (blanking delay) on pin 10 of the TIA  - that input still needs to be smooth and ripple free. C242 and C243 take care of that. The TSR 1-2450 only requires a (22uf) cap if the input voltage is greater than 32v.  The .1uf that it sees won't hurt it at all. 

What does pin 10 do if it needs 9V at the TIA chip? Nothing the TIA outputs is anywhere near this level.



#27 Schizophretard OFFLINE  

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Posted Tue Mar 14, 2017 7:40 AM

I don't comprehend what this modifications does or its benefits. Can you elaborate?



#28 mojoatomic OFFLINE  

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Posted Tue Mar 14, 2017 8:15 AM

I don't comprehend what this modifications does or its benefits. Can you elaborate?

The TSR 1-2450 is a direct replacement for the 7508 voltage regulator. It has a smoother output, can accept a larger range of voltage inputs, & produces almost no heat since it operates at near 98% efficiency. Further, it has built in short circuit protection and also actively filters RF, by basic nature of it's design. 



#29 mojoatomic OFFLINE  

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Posted Tue Mar 14, 2017 8:23 AM

What does pin 10 do if it needs 9V at the TIA chip? Nothing the TIA outputs is anywhere near this level.

It still gets it. Adding this part in no way changes the schematic or layout of power distribution in any way. 9v unregulated (or whatever your power supply is actually outputting) is still pulled from the + leg of C241 before it reaches A203 which is now a TSR 1-2450, and is still sent to the same place it was before. 



#30 tep392 OFFLINE  

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Posted Tue Mar 14, 2017 9:10 AM

What does pin 10 do if it needs 9V at the TIA chip? Nothing the TIA outputs is anywhere near this level.

The schematic shows two diodes between the color adjustment pot and the 5V leg of the regulator. They clamp the voltage to about 6.5V at the pot , which is then adjusted down from there and fed to pin 10 on the TIA.

 

tiasch.jpg



#31 -^CrožBow^- ONLINE  

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Posted Wed Mar 15, 2017 8:52 AM

I had been thinking of getting some of these for most of my vintage consoles as well, but also read threads on other forums where people noticed lots of noise in the audio output of their systems and video interference as well. 

 

I can think of three consoles that would really benefit from this the most:

 

7800 - as the normal 7805 gets crazy warm on those things.

Genesis - as there are 2 of them in that thing side by side and the model 1s really get quite warm in that area.

Intellivision - I believe there is both a 7805 and a 7812 in those things. And as most know that own an intellivision, the entire power supply area gets hot enough to manifold cook with.

 

So I know the Traco's Mojo listed are supposed to be the best, but I am curious to hear of anyone that has used the Oki brand buck converteres as well. Their spec sheets also state they don't require any external components and supposedly feature similar circuit protection and RF filtration?



#32 Kosmic Stardust OFFLINE  

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Posted Thu Mar 16, 2017 1:40 AM

I had been thinking of getting some of these for most of my vintage consoles as well, but also read threads on other forums where people noticed lots of noise in the audio output of their systems and video interference as well. 

Any HF ripple would get absorbed by the filter capacitor, would it not?



#33 -^CrožBow^- ONLINE  

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Posted Thu Mar 16, 2017 7:57 AM

Any HF ripple would get absorbed by the filter capacitor, would it not?

 

Well I would think if it was just a matter of adding in an additional cap off the input that those threads would have mentioned doing that. But again it is conflicting information all over the place. I really do see a use for these in the vintage systems as it would keep them much cooler inside while operating for long periods of time and that can only be a good thing for all other components inside the case. Especially any filter caps for the power area. 

 

So yes, I'm curious to know the results from the OKI versions of these converters. My only concern with the Treco units here, is their size. They are much larger than a standard 7805. So on most consoles you would have to remove whatever heatsink was being used previously. It shouldn't be needed anymore if what I've read is true with these buck converters basically generating no heat. But still the size of the Treco units could be challenging in the case of the 5200 and Genesis where their 7805s are pretty close to each other side to side and back to back. Can't really tell without seeing one of these in person.

 

Hell my Genesis is modded and abused pretty well as it is, maybe I should just pick up about 3 or 4 of these and try them in some systems. I still think an Intelly would benefit the most given how much heat those damn things create.



#34 Kosmic Stardust OFFLINE  

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Posted Thu Mar 16, 2017 10:02 PM

PM sent. I would like to buy some samples.



#35 ApolloBoy OFFLINE  

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Posted Fri Mar 17, 2017 10:26 AM

The 7805s are actually a good distance apart from each other on both the 5200 and model 1 Genesis, and actually the Treco regulators shown by the OP are only slightly bigger than a 7805 minus heat sink.

In fact I just installed some switching regulators in my 5200 yesterday and so far so good. I recommend installing a 220 uF cap across the output though, since you'll get some significant video interference otherwise.

#36 mojoatomic OFFLINE  

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Posted Fri Mar 17, 2017 10:33 AM

The 7805s are actually a good distance apart from each other on both the 5200 and model 1 Genesis, and actually the Treco regulators shown by the OP are only slightly bigger than a 7805 minus heat sink.

In fact I just installed some switching regulators in my 5200 yesterday and so far so good. I recommend installing a 220 uF cap across the output though, since you'll get some significant video interference otherwise.

You installed the Traco units and had interference before installing the cap, or another type of replacement? 



#37 ApolloBoy OFFLINE  

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Posted Fri Mar 17, 2017 10:42 AM

I didn't use the Treco regulators, I used some inexpensive ones I found on eBay for like $2 each. The caps were put in when I installed the regulators, as I've experimented with switching regulators before and had interference issues without that extra capacitor.

Edited by ApolloBoy, Fri Mar 17, 2017 10:43 AM.


#38 -^CrožBow^- ONLINE  

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Posted Fri Mar 17, 2017 11:16 AM

You installed the Traco units and had interference before installing the cap, or another type of replacement? 

 

So the Treco's provide all the cap filtering internally and do not require additional caps off the input or output lines? My main concern is interference with video and audio since most all of my units have AV mods in place to prevent as much interference as possible and get a clean picture. Wouldn't make sense to pop these bad boys in and have to do additional stuff to try and prevent it?



#39 mojoatomic OFFLINE  

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Posted Fri Mar 17, 2017 1:44 PM

 

So the Treco's provide all the cap filtering internally and do not require additional caps off the input or output lines? My main concern is interference with video and audio since most all of my units have AV mods in place to prevent as much interference as possible and get a clean picture. Wouldn't make sense to pop these bad boys in and have to do additional stuff to try and prevent it?

Here's the datasheet 

 

The Traco's require no external filtering up to 32v, after which they need a 22uf cap.  As for your application, you'd just have to try one and see - everything else is academic :-)

 

YMMV, but this provided a cleaner RF picture in a 2600 that originally had the 7508. It was a successful experiment. 

 

On another note... you can replace C242 & C241 with whatever you want, within reason. The net result will be greater filtering. You can, and I have, for example, many times used the filter caps from the 6 switch units on 4 switchers to help kill ripple. .22uf substituted for .1uf is actually a very good thing. 

 

The reason Traco chose the 22uf is that for high DC ripple like found in switching power supplies, you need capatience at low ESR - hence the electrolytic. 

 

Something else I've been playing around with is killing the arc on the power contacts. Turn off the lights with a board removed and you'll see them arc like MAD when you switch them on. I just put a 0.1 µF cap + 100 Ω resistor in line with the + side... and no more arcing. Should make them last quite a bit longer. 


Edited by mojoatomic, Fri Mar 17, 2017 1:48 PM.


#40 mojoatomic OFFLINE  

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Posted Fri Mar 17, 2017 1:53 PM

I've had a few guys ask if I'm selling the Traco's - truth is I just ordered a few to experiment with. I could get another Allied order together if there's enough interest though. If I buy enough of them I can get them at a price that won't make folks choke :-)  Truthfully... you don't use these to save money, but in quantity they're not that bad. 



#41 -^CrožBow^- ONLINE  

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Posted Fri Mar 17, 2017 2:43 PM

I've had a few guys ask if I'm selling the Traco's - truth is I just ordered a few to experiment with. I could get another Allied order together if there's enough interest though. If I buy enough of them I can get them at a price that won't make folks choke :-)  Truthfully... you don't use these to save money, but in quantity they're not that bad. 

I actually just ordered 5 of them from Allied about 2 hours ago...hehe. I will put two in my primary Genesis to see how it looks and operates. I will also put one into my 7800 and see how that goes. Though my 7800 is a real problem child. Never had good RF, and I've tried the simple composite Mod...with horrible jailbar and ghosting issues, the LHE mod, which looked fine on an actual CRT, but still had horrible ghosting and color bleed on the blue hues that was very easily seen on S-video, and a newer s-video mod from Magic Knight that has so far produced the best overall picture on S-vid, but the colors are off more than the other two...ugh. Point being, I'm not sure if I care if I blow it up or not at this point! LOL

 

The last 2 would be used on my primary 5200.

 

Question...I know there is a 7805 on the Intelly, is the other regulator a 7812 and are there DC buck converters like the Traco units for 12 volts? Because of all the classic consoles I own, the Intellivisions all get stupid hot from the regulators and it is no wonder many of them cooked themselves back in the day being played while on carpeting..etc.



#42 -^CrožBow^- ONLINE  

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Posted Fri Mar 17, 2017 2:45 PM

Truthfully... you don't use these to save money, but in quantity they're not that bad. 

 

Actually you would be saving money. They would require less overall power to operate and do their job. As such each console you convert successfully to this would be using about half the wattage needed to operate. At least from the 7805 side of things if the data sheets are to be believed? This would also mean that the wall warts won't get as hot because they don't have as much current being drawn from them so they too will operate a tad cooler. Increases the life span of everything around it and shaves a few KW hours over time in the process....yes?



#43 mojoatomic OFFLINE  

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Posted Fri Mar 17, 2017 2:49 PM

 

Question...I know there is a 7805 on the Intelly, is the other regulator a 7812 and are there DC buck converters like the Traco units for 12 volts? Because of all the classic consoles I own, the Intellivisions all get stupid hot from the regulators and it is no wonder many of them cooked themselves back in the day being played while on carpeting..etc.

The TSR 1-24120 is the 12v variant



#44 Kosmic Stardust OFFLINE  

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Posted Sun Mar 19, 2017 3:10 PM

I sent a PM to MojoAtomic but I thought I'd share my thoughts. I haven't bought anything yet but I found this substitute which appears to be around half the price of the part number MojoAtomic used.

 

This one looks pretty good at half the price of the part you quoted (1A with short protection), and likely much better performance than the typical 7805 w/ heat sink:

http://www.digikey.c...2201-ND/4930585

 

Datasheet:

https://www.recom-po...R-78Exx-1.0.pdf

 

Would there be any disadvantage to using the cheaper part? Efficiency is still well above 90% and it comes with short circuit protection, for example if you wire a custom joystick the wrong way and plug it in and it shorts the console, nothing gets fried.

 

I am tempted to order a batch of them as all my 4th gen consoles and back used 7805 regulators and could use the upgrade. However I wonder if ripple current effect would cause jailbars? My Trubografx really needs a replacement, as it runs a bit warm and outputs 5.65V.

 

Also do I need a 220uF or 22uF electrolytic? Lot's of values all with 22 being thrown around, including .22uF as well, but those are all orders of magnitude difference in component value. Too high a value would stress the regulator on startup, and possibly momentarily "brown out" the console as VCC climbs up to spec. If it takes more than a couple milliseconds to reach 5V, would that negatively impact initialization and boot sequence?



#45 Osgeld OFFLINE  

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Posted Sun Mar 19, 2017 3:54 PM

I sent a PM to MojoAtomic but I thought I'd share my thoughts. I haven't bought anything yet but I found this substitute which appears to be around half the price of the part number MojoAtomic used.

 

Would there be any disadvantage to using the cheaper part? Efficiency is still well above 90% and it comes with short circuit protection, for example if you wire a custom joystick the wrong way and plug it in and it shorts the console, nothing gets fried.

 

I am tempted to order a batch of them as all my 4th gen consoles and back used 7805 regulators and could use the upgrade. However I wonder if ripple current effect would cause jailbars? My Trubografx really needs a replacement, as it runs a bit warm and outputs 5.65V.

 

Also do I need a 220uF or 22uF electrolytic? Lot's of values all with 22 being thrown around, including .22uF as well, but those are all orders of magnitude difference in component value. Too high a value would stress the regulator on startup, and possibly momentarily "brown out" the console as VCC climbs up to spec. If it takes more than a couple milliseconds to reach 5V, would that negatively impact initialization and boot sequence?

 

first glance the input voltage window is a bit smaller, which means it doesnt have to deal with as much. There's probably a bunch of little differences in performance tween the two, but realisticly for the intended use I doubt it would make much difference 

 

as far as caps go, most of my designs include a small and a large cap for input and output filtering, like lets say a 0.1uf and a 100uf in parallel ... small caps smooth out high frequency noise, big caps smooth out low frequency noise (btw there is math to it all but I will spare everyone) 

 

 

also short circuit protection, only protects that part (7805 has it as well, it gets hot and starts to oscillate hehe, but it it by design to do that) only protects that part, so if you short out a couple pins on the CPU enough to shut this thing off, you probably toasted those IO on the CPU doing so

 

its like a fuse, its not there to protect your crap, its there to keep your house from burning down when your crap gets messed up


Edited by Osgeld, Sun Mar 19, 2017 4:00 PM.


#46 Kosmic Stardust OFFLINE  

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Posted Mon Mar 20, 2017 3:28 AM

So the filter circuitry already inside the console (assuming the caps aren't bad) is inadequate for a switching regulator? I'm thinking as a direct drop in replacement on these for the 7805s and forget it.

 

 

 

also short circuit protection, only protects that part (7805 has it as well, it gets hot and starts to oscillate hehe, but it it by design to do that) only protects that part, so if you short out a couple pins on the CPU enough to shut this thing off, you probably toasted those IO on the CPU doing so

 

its like a fuse, its not there to protect your crap, its there to keep your house from burning down when your crap gets messed up

 

Not what I meant. Most I/O pins can withstant momentary shorts to ground, but not in all cases. I mean like your joystick have a short in it or improper wiring and VCC and GND literally get shorted together. It can easily happen; almost did it with this joystick LED mod I bought that could have shorted out my Atari system had I not tested it first using a standalone DC adapter. Single piece of heat shrink around both non-insulated leads on a 5V LED with embedded resistor. Who does that kind of shoddy craftmanship?



#47 Schizophretard OFFLINE  

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Posted Mon Mar 20, 2017 4:47 AM

The TSR 1-2450 is a direct replacement for the 7508 voltage regulator. It has a smoother output, can accept a larger range of voltage inputs, & produces almost no heat since it operates at near 98% efficiency. Further, it has built in short circuit protection and also actively filters RF, by basic nature of it's design. 

In layman's terms does that mean the most noticeable benefit is less RF interference?

#48 -^CrožBow^- ONLINE  

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Posted Mon Mar 20, 2017 9:26 AM

In layman's terms does that mean the most noticeable benefit is less RF interference?

 

I stated the advantages off hand a few posts up, but the main advantages are better power efficiency which is less heat begin given off inside the console. Would also reduce the heat the wall warts produce since they wouldn't be getting driven as hard to provide as much current.

That to me are the two main advantages of this. Less heat or near non-existent, plus better power efficiency, which reduces overall cost to operate the systems and results in a hoped longer life of the components inside the system.

 

I believe my order will arrive tomorrow, I will promptly install them into my Genesis first and see how the picture quality is. From there I will move to my 7800.



#49 tep392 OFFLINE  

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Posted Mon Mar 20, 2017 10:37 AM

Heat is a significant factor in the life of electrolytic caps.  They are going to go bad eventually, but you may get a little more life out of them.  I'm particularly concerned with the three large power filtering caps that are right next to the very hot heat sink in my 1050 drive.  I also don't like pulling disks out and finding them warm to the touch.



#50 mojoatomic OFFLINE  

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Posted Mon Mar 20, 2017 12:14 PM

Heat is a significant factor in the life of electrolytic caps.  They are going to go bad eventually, but you may get a little more life out of them.  I'm particularly concerned with the three large power filtering caps that are right next to the very hot heat sink in my 1050 drive.  I also don't like pulling disks out and finding them warm to the touch.

Those 1050's are the WORST for heat buildup. Several VR's in them, and I imagine they would benefit greatly with newer tech. 






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