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Retrotink 2X inside 800 - technical questions

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Hey Atari fans -

 

I'm messing around with the idea of putting a Retrotink 2X inside an 800, so an HDMI cable can just come straight out the back of the computer (instead of RF)..  I have two questions:

 

1.  If I 'create' a short S-Video cable by tapping into the monitor output ports (or elsewhere on the board), will that create noticeable additional noise on the video out if I use the regular monitor port with a CRT?   (and when not using the HDMI out) 

 

2.  I see the Retrotink 2X needs a "5V at least 1A" psu - so assuming it needs up to 5W at certain times -- is there any chance an 800 w/Incognito (instead of 3 ancient giant 16KB RAM boards :) ) -- would have enough margin to sustain this on the 5V output?     I plan to measure the retrotink for 'real' output via a USB power meter once I get it..  

 

Thanks.. 

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I wouldn't trust to luck with your 800 PSU, I think you would be pushing it, maybe you would have to add an extra PSU

to power the 2X

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2 hours ago, Xebec said:

2.  I see the Retrotink 2X needs a "5V at least 1A" psu...

I was just looking at the manual for the 2X-Pro, and it says there 500 mA.

 

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Just now, MrFish said:

I was just looking at the manual for the 2X-Pro, and it says there 500 mA.

 

Thanks! - Website said 1A but had not checked manual - thank you! 

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Posted (edited)
7 hours ago, Xebec said:

Hey Atari fans -

 

I'm messing around with the idea of putting a Retrotink 2X inside an 800, so an HDMI cable can just come straight out the back of the computer (instead of RF)..  I have two questions:

 

1.  If I 'create' a short S-Video cable by tapping into the monitor output ports (or elsewhere on the board), will that create noticeable additional noise on the video out if I use the regular monitor port with a CRT?   (and when not using the HDMI out) 

 

2.  I see the Retrotink 2X needs a "5V at least 1A" psu - so assuming it needs up to 5W at certain times -- is there any chance an 800 w/Incognito (instead of 3 ancient giant 16KB RAM boards :) ) -- would have enough margin to sustain this on the 5V output?     I plan to measure the retrotink for 'real' output via a USB power meter once I get it..  

 

Thanks.. 

 

Well, a stock (fully-populated 48KB RAM + OS/ROM) A800 consumes about 15.5 - 16.5 watts, on idle. 

 

An 800/Incognito, just booted at SDX with NO .ATRs attached, consumes about 9.8w to 10.4watts, mostly idling at 9.8W.

 

Besides having a capable on-board power-supply, you certainly have plenty of juice / latitude left for bringing that Analog-to-Digital converter / scaler on-board, and feed it directly from the 800's power board. You even have +5v, -5v AND +12v available in ALL of the expansion slots (!)

 

Overall, I strongly recommend using the 30Watts 9v A/C units when feeding the 800, because (on the scope) they appear the cleanest, and are definitely more capable than the 800's stock P/S.

Edited by Faicuai
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5 hours ago, Faicuai said:

 

Well, a stock (fully-populated 48KB RAM + OS/ROM) A800 consumes about 15.5 - 16.5 watts, on idle. 

 

An 800/Incognito, just booted at SDX with NO .ATRs attached, consumes about 9.8w to 10.4watts, mostly idling at 9.8W.

 

Besides having a capable on-board power-supply, you certainly have plenty of juice / latitude left for bringing that Analog-to-Digital converter / scaler on-board, and feed it directly from the 800's power board. You even have +5v, -5v AND +12v available in ALL of the expansion slots (!)

 

Overall, I strongly recommend using the 30Watts 9v A/C units when feeding the 800, because (on the scope) they appear the cleanest, and are definitely more capable than the 800's stock P/S.

Where would I get the 30W 9V A/C unit?  

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1 hour ago, Xebec said:

Where would I get the 30W 9V A/C unit?  

It's the 1050's external power-supply, with a smaller-footprint but taller profile, and both mains and load cables on the front-side.

 

 

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Posted (edited)
8 hours ago, Faicuai said:

Well, a stock (fully-populated 48KB RAM + OS/ROM) A800 consumes about 15.5 - 16.5 watts, on idle. 

 

An 800/Incognito, just booted at SDX with NO .ATRs attached, consumes about 9.8w to 10.4watts, mostly idling at 9.8W.

One issue is I believe most of the power reduction is on the +12V rail due to elimination of the 4116 DRAM chips, on the Incognito modded 800 almost all the power consumption is on the +5V rail and could be near the 1A limit of a typical 7805, though Atari did add a 33 ohm bypass resistor to deliver additional current.

 

If adding an internal component that is supposed to consume 500mA I would suggest adding a second 7805, or replacing the stock one with one rated at 1.5A such as the L7805CV.

Edited by BillC

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Posted (edited)
1 hour ago, BillC said:

One issue is I believe most of the power reduction is on the +12V rail due to elimination of the 4116 DRAM chips, on the Incognito modded 800 almost all the power consumption is on the +5V rail and could be near the 1A limit of a typical 7805, though Atari did add a 33 ohm bypass resistor to deliver additional current.

 

If adding an internal component that is supposed to consume 500mA I would suggest adding a second 7805, or replacing the stock one with one rated at 1.5A such as the L7805CV.

We'll put this to the test, tomorrow.

 

I will extract Incognito, and fire-up the system (leaving it to 6502, Antic, GTIA, Pokey, PIA and supporting chips consumption).

 

If total wattage exceeds 5 watts, it is clear that the system core 5v-supply is designed for MORE than 1amp @ 5 volts... unless those chips work at something other than 5v.

Edited by Faicuai

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3 minutes ago, Faicuai said:

We'll put this to the test, tomorrow.

 

I will extract Incognito, and fire-up the system (leaving it to 6502, Antic, GTIA, Pokey, PIA and supporting chips consumption).

 

If total wattage exceeds 5 watts, it is clear that the system core 5v-supply is designed for MORE than 1amp @ 5 volts... unless those chips work at something other than 5v.

The 33ohm/2W 7805 bypass resistor supplies an additional 120 to 150mA(depending on unregulated DC supply voltage) on top of what the 7805 delivers. I'm just saying that if there is a potential issue when adding additional internal devices then replacing the typical 7805 with the L7805CV would be a good idea. They aren't expensive, DIGIKEY has the L7805CV priced as low as $0.50 versus $.029 for the 7805, and the L7805CV are available from eBay for as low as 10 for less than $1(with free slow shipping from china).

 

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You might want to install it so you can access the output select button through a grille. I am not sure if it remembers the last selected value.

 

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13 hours ago, BillC said:

The 33ohm/2W 7805 bypass resistor supplies an additional 120 to 150mA(depending on unregulated DC supply voltage) on top of what the 7805 delivers. I'm just saying that if there is a potential issue when adding additional internal devices then replacing the typical 7805 with the L7805CV would be a good idea. They aren't expensive, DIGIKEY has the L7805CV priced as low as $0.50 versus $.029 for the 7805, and the L7805CV are available from eBay for as low as 10 for less than $1(with free slow shipping from china).

 

Ok, so here are the test's results:

 

1. Power Consumption, 800 WITH Incognito, idle: 10.8 Watts

2. Power Consumption, 800 MINUS Incognito, idle: 9.1 Watts

3. External P/S parasitic  consumption / drag: 1.8 Watts

 

Therefore:

 

1. System's net power-consumption (without Incognito) is 7.3 Watts. This is definitely higher than 1.15amp @ 5v.

2. Incognito's net power-consumption (on idle) is 1.7 Watts.

 

I do wonder if there is a design issue, then, with the +5v supply on the 800, per your observations and component-ratings (?)

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7 hours ago, Faicuai said:

1. System's net power-consumption (without Incognito) is 7.3 Watts. This is definitely higher than 1.15amp @ 5v.

How are you measuring power consumption, output of the AC adapter, unregulated DC from the bridge rectifier, other?

1A unregulated DC current into the 7805/33ohm resistor would provide 5W power to the circuitry, but would result in 9 to 10W actual power consumption, the difference is the power dissipated as heat by the 7805 and 33ohm/2W resistor. 

 

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Any recommendations for how to best avoid the noise of wiring up chroma/luma from the monitor socket to the retrotink?  If I do this project I'll be want the 800 to still work with Chroma/Luma CRTs ..  

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