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cbmeeks

Any new TI power supplies?

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So, while I work on possibly replacing my PEB power supply, I was wondering if there are any good, new PSU's for the TI itself?

 

I've bought modern supplies for my C64 and Apple II so why not for my TI?

 

I'm pretty good with a soldering iron so I guess I could recap the PSU.  Correct me if I'm wrong, but isn't the external brick just a transformer?  I've never opened it up.

 

But, having a nice new PSU that is reliable would be ideal.

 

Thanks!

 

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This supply, the Mean Well P25A13A-R1B, has seen some interest and use.  Note that it directly outputs 5V/12V/-5V DC so this is a replacement for both the internal power supply (which outputs these) and the external transformer (which outputs 16V/8V/5V for regulation down to the aforementioned values).  Switching, socket installation, and a power LED if desired, would be left as an exercise to the user. 

Edited by pixelpedant
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I don't know if there are any new power supplies made specifically for the TI or not, but the original one only outputs +5 VDC, -5 VDC, and 12 VAC, so you could use any JAMMA-type switched-mode power supply (like this one - http://www.arcadeshop.com/i/804/switching-power-supply-15-amp.htm - for example), which would mean you wouldn't need the external brick anymore.

 

However, unless you're having problems with the original power supply, why replace it? The original power supply is a very simple design; not much on there to fail:

 

http://www.mainbyte.com/ti99/hardware/power_supply.html

 

If you wanted to replace the electrolytic capacitors just for good measure, it wouldn't take long to do because there aren't many of them on there. Use first-tier (e.g., Rubycon, Nichicon, United Chemi-Con, Panasonic, Sanyo), high-temp @ long-life capacitors and it will probably last for a very long time.

Edited by MaximRecoil

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3 hours ago, cbmeeks said:

So, while I work on possibly replacing my PEB power supply, I was wondering if there are any good, new PSU's for the TI itself?

But, having a nice new PSU that is reliable would be ideal.

17 minutes ago, pixelpedant said:

This supply, the Mean Well P25A13A-R1B,

15 minutes ago, MaximRecoil said:

However, unless you're having problems with the original power supply, why replace it? The original power supply is a very simple design; not much on there to fail:

The Mean Well one shown by @pixelpedant is the one I plan to get after @arcadeshopper comes out with the new internal board for it.  

 

You ask why replace it if you are not 'currently' having problems with it?  Well, why wait until failure, I mean the thing is 35 years old.   Replacing the original coffee cup warmer will let our machines run cooler,  and give the majority of us the rest of our lives without worry.  Also, since some people will be opening them up for the new F18A MK2, they may find that it's a perfect time to update as much as possible, even add the @jedimatt42 keyboard upgrade.  Also the new board may have a power tap or two for future upgrades/features.  It's on my 'bucket list'.

 

On this, I have a question Greg, will an extra power tap be there for easy installation of Matt's keyboard upgrade?

Also any news on a power tap for a USB power outlet?

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1 hour ago, --- Ω --- said:

You ask why replace it if you are not 'currently' having problems with it?  Well, why wait until failure, I mean the thing is 35 years old.   Replacing the original coffee cup warmer will let our machines run cooler,  and give the majority of us the rest of our lives without worry.  Also, since some people will be opening them up for the new F18A MK2, they may find that it's a perfect time to update as much as possible, even add the @jedimatt42 keyboard upgrade.  Also the new board may have a power tap or two for future upgrades/features.  It's on my 'bucket list'.

 

Or, you might find that that little wall adapter-type, probably made-in-China, replacement power supply isn't as robust as the original. Also, the motherboard in your TI is just as old, and has a lot more likely points of failure, especially those TTL chips, and in my experience with TTL chips from the 1980s, they fail like it's their job.

 

TI99-4A_Motherboard_%26_PSU.jpg

 

What do you see on there that's likely to fail, especially after you've replaced the 6 electrolytic capacitors? Most of those components, such as the coil, diodes, and resistors don't fail very often. That DIP14 IC is an 89-cent part. Those linear voltage regulators are cheap too, as is that transistor. You could replace every component on that PCB for not a lot of money, with the possible exception of that DIP8 IC, which doesn't seem to be available new anymore and might be hard to find. If I were concerned about it, I'd replace the electrolytic capacitors, the TO-220 package linear voltage regulators, that TO-92 package transistor, and the two ICs (or just the DIP14 one if I couldn't find the DIP8 one for cheap). That covers everything on the power supply PCB that contains an electrolyte or silicon.

Edited by MaximRecoil
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In my case I've had one power supply fail, so when I get the new board and power supply, the one that I remove will go into the currently broken unit.  I'm also looking to add a few 'new items' to my planned TI "Super Console", so will just feel better going with as much new tech as possible.  This is planned to be the last TI I ever own and my final upgrade (to the console) so I want to go all out.  Other people have different wants and goals, I'm just happy @arcadeshopper is around to help me feed my addiction and make another check on my bucket list.

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I gotta admit, if you're upgrading with some modern parts, having a supply that can source you a few extra amps of +5VDC for accessories is a nice convenience. Host-powered Genesis controller adapters , TIPIs, memory sidecars, NanoPEBs, etc.

 

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On the down side...
Letting older ICs have as much current as they will take, is to reconcile them to a finite lifetime. Better to provide for some type of current limiting. When a part fails in closed mode(shorts), the unlimited current can also cause unlimited damage to other components in that circuit path.:o

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39 minutes ago, JB said:

I gotta admit, if you're upgrading with some modern parts, having a supply that can source you a few extra amps of +5VDC for accessories is a nice convenience. Host-powered Genesis controller adapters , TIPIs, memory sidecars, NanoPEBs, etc.

 

A JAMMA type power supply like I linked to above would give you all the amps you could ever want (15 amps on +5 VDC), but that little Mean Well wall adapter power supply only has 2.5 amps on +5 VDC, and the TI's motherboard will be drawing about 1 amp of that at idle.

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That's a neat little power supply!  A guy sure could hang a lot of stuff off of his TI for sure!

 

PS.thumb.png.730f038a54ee80b4e35e6a13866a47cd.png

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1 hour ago, --- Ω --- said:

That's a neat little power supply!  A guy sure could hang a lot of stuff off of his TI for sure!

Yeah, that type of power supply has been the standard for video arcade machines since the JAMMA era began (1986), and the Happ Power Pro has been a popular one for a long time. The other popular one, at least with arcade operators, is Peter Chou from Betson Imperial:

 

https://www.betsonparts.com/amusement-redemption/power-supplies/15-amp-power-supply.html

 

Those were the original design that others copied, and popular enough that some people use the term "Peter Chou" as a generic term for that type of power supply, like people using the term "Kleenex" for any brand of tissues. Here's some information about them from arcade guru Ken Layton:

Quote

Peter Chou is an electronic engineer and designer. He owns and operates his own power supply manufacturing plant in Taiwan (U-San Electron Co. Ltd). His company makes both the screw terminal enclosed and silver box computer style switching regulator power supplies for the amusement machine and gaming industries.

 

His company was the first to come up with a reliable power supply and many game manufacturers began using his power supply. So much so that the term, "Peter Chou power supply" has become synonomous with switching regulator power supplies regardless of make/model.

 

That "F" number on the outside cover and on the circuit boards is his personal identification number (their equivalent of a Social Security number). His power supplies are very reliable, economical, and easy to repair. They are distributed by Betson in the USA. Peter Chou power supplies are still being manufactured.

 

Attached is a picture of a genuine Peter Chou 12 amp power supply with the screw terminals.

However, they aren't as popular with regular people because Betson is the primary retailer for them and if you're not an operator with an account with them, you'll end up paying big money for shipping, and they're one of those annoying companies that won't tell you the shipping cost upfront.

Edited by MaximRecoil

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Having a spare power supply with recent components is in our projects, in fact we are working on it, if you have ideas to integrate they are welcome.  In the events we do in schools we use a jamma video game power supply.

IMG_20191006_163346_999.jpg

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I personally feel than an adapter for a PicoATX (that has a simple IC that generates the missing -5v rail) would be the ideal solution.  The devices are in wide circulation with high demand, and are able to provide upwards of 120W for the premium models. MORE than adequate to power lots of sidecars and other 5v hungry devices.

 

 

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I'd prefer to take the juice from power taps on the soon to be new internal card mounted inside the TI and have it distributed through one or two USB ports mounted on the TI.  This would eliminate multiple wall warts and long cords.  TIPI's and other yet to be invented items could get their power where it's used, at the machine.

Running so much current through the sidecar slot/trace scares me.

USB.JPG.89ff834335910c2d06e3bfa52bea6e96.JPG

 

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The bus is only rated for 500mA, according to the manual.  If I were to add more power to the 5v rail there, I would do it behind a beefy isolation diode. That way the injected 5v rail would not course its way back up into the motherboard where it does not belong.  Ironically, a modified speech sidecar would be an ideal place to do the power injection, due to it terminating the +5v rail. Instead of doing the bridge mod, you would add a +5v rail on a diode. Then your hungry device (like a TIPI) could get regulated 5v right off the bus without issue, and not pose a hazard to the upstream devices.

 

Either way, the picoATX has +5v rails in copious abundance (seriously, it has 5 of them on the ATX header, and a big beefy one on the HDD power rail), and wiring up a few USB ports just for power would be trivially easy. Bear in mind that USB power spec is maxed out at 2A. Depending on the device you are attaching, it might actually need more than that. (Especially if there are rechargeable batteries getting topped up in there, such as say, if you were to wire up a ramdisk on the sidecar.) As a consequence, do not use the port to charge electronic devices like phones unless you appropriately rate limit the amperage.

 

I mostly favor the picoatx idea because good quality 12v barrel type power bricks are a commodity item, and the picoatx itself has a strong mass-production supply chain, making them very easy to obtain inexpensively. (Compared to the more unusual power supply favored in the above postings, which I understand can be hard to source.)  The only issue it has is the missing -5v rail, which can be resolved with a single IC on the breakout board. Since it provides multiple +5v rails, you could wire up all kinds of power-only USB ports on the back with it, without causing voltage sag on the rail you use to run the TI's motherboard.

 

 

 

 

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12 hours ago, --- Ω --- said:

I'd prefer to take the juice from power taps on the soon to be new internal card mounted inside the TI and have it distributed through one or two USB ports mounted on the TI.  This would eliminate multiple wall warts and long cords.  TIPI's and other yet to be invented items could get their power where it's used, at the machine.

Running so much current through the sidecar slot/trace scares me.

Additionally, if people start making add-ons that try to power themselves from the expansion bus, this introduces incompatibilities with an unmodified 4a.

USB cables means the "standard" for power is something that everyone can use easily. Plug into a hub on the back of the TI if you have a power mod, or a random phone charger if you don't.

 

 

 

 

PicoATX does sound like a good replacement power supply to me. The lack of -5V is disappointing, but easily rectified, and the other advantages seem to outweigh it.

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On 10/19/2019 at 8:29 AM, wierd_w said:

I mostly favor the picoatx idea because good quality 12v barrel type power bricks are a commodity item, and the picoatx itself has a strong mass-production supply chain, making them very easy to obtain inexpensively. (Compared to the more unusual power supply favored in the above postings, which I understand can be hard to source.)  The only issue it has is the missing -5v rail, which can be resolved with a single IC on the breakout board. Since it provides multiple +5v rails, you could wire up all kinds of power-only USB ports on the back with it, without causing voltage sag on the rail you use to run the TI's motherboard.

If you're including JAMMA-type power supplies as being hard to source, they aren't, since they've been an industry standard for over 30 years. Plus, they all have a -5 VDC rail, and their screw terminals make it very easy to connect them to anything.

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On 10/18/2019 at 6:59 PM, MaximRecoil said:

You could replace every component on that PCB for not a lot of money, with the possible exception of that DIP8 IC, which doesn't seem to be available new anymore and might be hard to find.

The TL331CP (or the approved alternate TL331IP) can still be found (I found one Hong Kong seller claiming to have 2600 of them about five minutes ago on a cursory parts search using the IEEE website). Note that both variants are out of production, unfortunately, so YMMV.

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