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Console power supply 12v rating?


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#1 OLD CS1 OFFLINE  

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Posted Sun May 27, 2018 9:11 PM

I have been digging around with some simple Google-fu to try to turn up the rating of the 12v rail from the console power supply.  I am guessing there are some documents somewhere not indexed where this data is found, but I place my bet someone has this indexed deep in some grey matter :)

 

Short: I want to power an LCD screen which has a listed draw of 12V at 400mA.  I suspect it draws less at 12V since it is rated for 5V at 2A but draws less.



#2 Stuart OFFLINE  

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Posted Mon May 28, 2018 2:57 AM

The +12V regulator in the console power supply is a UA7812C which is rated at 1A. The console draws about 330mA from the +12V supply. Drawing another 400mA from the +12V supply is probably possible, but the regulator/heatsink are going to get pretty damned hot in their confined little space. Personally I'd hook the screen up to a separate external supply.



#3 OLD CS1 OFFLINE  

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Posted Mon May 28, 2018 10:27 AM

Thank you, Stuart!  I did find the current draw of the console on your website.  This morning I was going to dig through schematics, too.

 

I am going to rig up my DMM to figure out how much this device actually draws.  It has inputs for VGA, HDMI, and composite, so I have considered its use with an F18A console with video RAM removed, as well.

 

Most of those regulators in TO-220 packaging hold well around 250mA without heat-sinking, 500mA is recommended for a minimal to moderately-sized heat sink, and the 1A rating is with a good heat sink but I remember reading a manufacturer application for a 7812 which stated forced air cooling was recommended over convective cooling for 1A draw.



#4 iKarith OFFLINE  

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Posted Sun Jun 10, 2018 7:35 AM

There's also the idea of an aftermarket power supply for the TI.  I'm seriously considering the idea of going that route still.  Never know how long these old power supplies will last…



#5 OLD CS1 OFFLINE  

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Posted Sun Jun 10, 2018 11:09 AM

There's also the idea of an aftermarket power supply for the TI.  I'm seriously considering the idea of going that route still.  Never know how long these old power supplies will last…

 

acadiel has replaced one of his with an external brick. I have considered for many years replacing the power supply with a mounting board for a picoPSU, but in the past six years or so that I have toyed with the notion I have not been bothered.  I am slowly learning KiCad so maybe that will change.



#6 iKarith OFFLINE  

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Posted Wed Jun 13, 2018 11:11 PM

I was thinking that this would likely fit inside the console.  Of course it'd mean having mains in the console, and a switching PSU with caps that could carry a lot of voltage.  A little caution with the underside of the board is called for.  :)  External is possible too, I just don't know what I'd do with the plug at the back for an external brick.  DIN would make sense I guess?



#7 OLD CS1 OFFLINE  

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Posted Thu Jun 14, 2018 1:17 AM

Interesting.

 

FWIW, the 12V output of the console does drive the screen in question with no discernible increase in heat from the power supply over a lengthy game-playing session.  Granted, this is a "QI" power supply so the original may be different.  The screen works pretty well and has audio.  With SVGA input I think it would make a great display for an F18A-equiped unit with the VDP RAM removed for extra power savings.



#8 acadiel OFFLINE  

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Posted Thu Jun 14, 2018 11:17 AM

I was thinking that this would likely fit inside the console.  Of course it'd mean having mains in the console, and a switching PSU with caps that could carry a lot of voltage.  A little caution with the underside of the board is called for.  :)  External is possible too, I just don't know what I'd do with the plug at the back for an external brick.  DIN would make sense I guess?

 

Maybe this one?  

SBU60-301

 

It has +5V, +12V, and -5V.



#9 iKarith OFFLINE  

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Posted Sat Jun 16, 2018 1:36 AM

Yes, the triple-rail unit is perfect for the TI—though Henry Courbis has the quad rail models that'd work well for most computers of the 1980s, so I'd be likely to get one of those so I have something to work with on other machines if it doesn't fit inside the console.  I could always put it outside the console, but it seems if I'm going to have an external unit can probably find one  pre-made.



#10 Stuart OFFLINE  

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Posted Sat Jun 16, 2018 2:22 PM

Interesting.

 

FWIW, the 12V output of the console does drive the screen in question with no discernible increase in heat from the power supply over a lengthy game-playing session.  Granted, this is a "QI" power supply so the original may be different.  The screen works pretty well and has audio.  With SVGA input I think it would make a great display for an F18A-equiped unit with the VDP RAM removed for extra power savings.

 

The QI power supply uses a switched mode design for the 12V supply rather than a simple regulator, so it produces less heat.

 

Glad to hear it all works!






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