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Old 02-13-2014, 12:12 AM   #1
ejonesss
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tivo series 4 power supply current capacity

does anyone know how many amps the power supply for the series 4 can supply on both the 5 volt and 12 volt wires?
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Old 02-13-2014, 01:45 AM   #2
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does anyone know how many amps the power supply for the series 4 can supply on both the 5 volt and 12 volt wires?
Unless TiVo publish that information I don't know how we would know, I guess we could set up a test bench and try to load each voltage but we don't know the mix of power that TiVo used for each voltage and what good would the power form each voltage do anybody ?
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Old 02-13-2014, 07:12 AM   #3
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does anyone know how many amps the power supply for the series 4 can supply on both the 5 volt and 12 volt wires?
Are you wondering if a particular replacement hard drive will be adequately served.

Trying to figure out if and how to use it to run 2 drives?

Is this one of those OS on SSdrive, media on spinning rust schemes?

If the S4s are like the previous (insert plural of Series here), then open it up and look for either a sticker wrapped around the biggest, highest voltage rated capacitor on the power supply circuit board giving the rated amperage at each output voltage, or look for that info silk-screened onto the circuit board itself.

But seriously, tell us why you need to know.
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Old 02-13-2014, 07:26 AM   #4
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Looking on the sticker where the cord plugs into the Tivo, I find the rating for the input of a TiVo HD (example) to be 2.4 Amps @ 120 Volts.
That converts to 288 VoltAmps. Break that down for the various output voltages.

288VA / 12V = 24A
288VA / 5V = 57.6A
288VA / 3.3V = 87.273A

Now, those figures represent what an unregulated power supply is capable of producing.

I'm pretty sure that the TiVo doesn't need currents that high to operate, so they regulate that current through resistors, coils, and capacitors.
So, you would need to trace each voltage rail to see which components are used on that rail and how they are interconnected.

From there, is even more math you'd have to do using the component ratings to find out how much current is being limited.

Now, it is most likely that the 120V is only converted to 12V and the other voltages are derived using the 12V rail, so then you would only need to use the output number of the 12V rail (288VA / 12V = 24A), and then you would need to figure out how the other rails are connected and how that current is divvied up.

This is where a schematic would be helpful. Unfortunately, TiVo hasn't published this info and no one here has taken the time to draw one up.
Here lately, I've been "blessed" with having more time on my hands. I'll make a note to myself to try and draw one up next time I open my Tivo to clean it. Of course, it's use would be limited, as there are two power supplies from different manufacturers used in the TiVo HD.

What are you planning to do with the power supply where you would need these numbers?
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Last edited by steve614 : 02-13-2014 at 07:34 AM.
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Old 02-13-2014, 07:49 AM   #5
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@unitron seeing that the single tuner (stream) mode has caused problems even on all of the roamio boxes it would be a waste of money to update to even a roamio base model

and the roamio base model uses external 12 volt power supply means that it can be powered from a car battery and something to charge the battery it would be a lot more economical to do that than to use a ups for power backup.

i got to thinking i could use 2 dc to dc converters

ebay item 321305751409 a
150W DC-DC Boost Converter 10-32V to 12-35V 6A Step Up Voltage Charger Power

to supply the 12 volts

and ebay item 261322520291 SUPERNIGHT™ DC-DC 12V/ 24V to 5V 10A Converter Step Down Regulator Module 50W

to supply the 5 volts

now my theory on the capacity comes about because i researched and each wire on an atx power supply would handle 2.5 amp and there are 2 yellow 12 volt wires and 4 red 5 volt wires and the rest are black ground
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Old 02-13-2014, 07:54 AM   #6
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I am not following what you are trying to accomplish here.

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Old 02-13-2014, 08:00 AM   #7
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replace the original series 4 power supply with one to make it like a roamio base model and would be cheaper than a base model
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Old 02-13-2014, 08:14 AM   #8
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Hmm. Seems kind of awkward to have multiple units to supply the various power requirements. Might consider looking at some of the game unit's power supply that have multiple power rails or some of the small form factor desktop PCs that use a brick for a power supply.
Unless you have lifetime on that premiere, by the time you invest your money and time it might be worth picking up a base Roamio when they have it on sale for 150.
Watch buying cheap power bricks, they might not give you a noise free power rail.


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Old 02-13-2014, 08:35 AM   #9
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@jmbach i was wanting to run the tivo from a battery

there are losses stepping 12 up to 110 with an inverter or ups then back to 5 and 12

where as the losses would be less if i could run a dc to dc converter from a battery and then use a battery tender or something to hold a charge on the battery.

it is like what goes on in a laptop you have the laptop plugged in and when the power goes out it still runs because of the battery.

my thought is to stick it to the old man and get the power features of the base model without the $200 price.
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Old 02-13-2014, 11:28 AM   #10
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Interesting concept. You might want to Google dc-dc atx power supply. You will need +3.3, +5, +12 volts at least. Plus you will need something that provides low ripple and noise.

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Old 02-13-2014, 01:13 PM   #11
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@jmbach i was wanting to run the tivo from a battery

there are losses stepping 12 up to 110 with an inverter or ups then back to 5 and 12

where as the losses would be less if i could run a dc to dc converter from a battery and then use a battery tender or something to hold a charge on the battery.

it is like what goes on in a laptop you have the laptop plugged in and when the power goes out it still runs because of the battery.

my thought is to stick it to the old man and get the power features of the base model without the $200 price.
What does running a Premiere from a battery gain you?

Is there some situation of which I'm unaware where the Premiere needs more power than can be delivered by the stock supply?

If you just want to keep it going when the power goes out, well, you should have it plugged into a UPS anyway.

And as I indicated, get out your #10 Torx driver, take off the lid, and see what it says on the power supply as far as how many Amperes it delivers at which voltage, and that'll answer your question.
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Old 02-13-2014, 01:15 PM   #12
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I'm still not certain I understand exactly what modification you have in mind, but in the event of a fire, you might be stuck having to prove that what you did had absolutely no connection whatsoever with the cause to keep your insurance from refusing to pay out.
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Old 02-13-2014, 01:44 PM   #13
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@unitron i want to be able to run it for like mobile use say in an rv
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Old 02-13-2014, 01:52 PM   #14
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i think i found something

http://www.short-circuit.com/categories/dcdc.html

unfortunately there are no amp ratings for the outputs.

they just connect to the 24 pin connector on the motherboard then has 1 sata 1 pata connector and 1 wire that connects to a car battery to allow mobile use of a computer
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Old 02-13-2014, 06:21 PM   #15
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@unitron i want to be able to run it for like mobile use say in an rv
See how much current the AC side draws and just use an inverter big enough.

Volts times Amps equals Watts (more or less, since we're talking AC and not DC) if you need to convert to compare the inverter's AC output figure to the TiVo's AC input figure.

And in this case Volts is a constant at 120.

Connect the DC side of the inverter to a battery and also have a hookup that'll let you recharge that battery when the vehicle's running and you can tap into its 12V system.

Anything else is too much hassle for too little reward.
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Old 02-14-2014, 07:08 PM   #16
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you see unitron the only feature of the roamio base model i would find useful would be the external power supply if i was to upgrade to the roamio base model.

seeing it uses an external power supply gave me the idea i could run it from a 12 volt battery.

if you was to cut the cord from the external power supply, strip the end and connect to a 12 volt source it would run the dvr

i wanted to know the amp capacity so i could know if the dc to dc converters could run it without failing.
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Old 02-15-2014, 09:20 AM   #17
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I found this thread in which people are saying the Premieres draw around 26 watts max.

26W / 120V = .217A

When you step down voltage, current goes up...

.217A * 12V = 2.6A

Convert that to watts...

2.6A * 12V = 31.2W (see note [1])

So, I would say you need a converter with a capacity rating of at least 12v @ 3 amps. You can go a higher rating just to be safe, but if you go higher, make sure to put an inline fuse on the wire between the DC voltage source and the converter. On second thought I recommend an inline fuse period. Better safe than sorry.

[1] My numbers could be off a little due to the AC to DC conversion. I don't remember if there are other calculations needed when taking that into consideration.
Having said that, I don't think they are that far off.
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Old 02-15-2014, 01:09 PM   #18
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you see unitron the only feature of the roamio base model i would find useful would be the external power supply if i was to upgrade to the roamio base model.

seeing it uses an external power supply gave me the idea i could run it from a 12 volt battery.

if you was to cut the cord from the external power supply, strip the end and connect to a 12 volt source it would run the dvr

i wanted to know the amp capacity so i could know if the dc to dc converters could run it without failing.
Instead of ruining your external supply, just go to Radio Shack or Fry's or wherever and get a barrel connector that matches inside and outside diameter and make sure you wire it up the same polarity as the external supply.

If the back of the TiVo and the external supply do not indicate polarity and you can't figure it out with a voltmeter, you have no business trying what you have in mind.
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Old 02-15-2014, 04:41 PM   #19
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To find the power requirement for a DC supply just look on the power adapter for the Roamio. It will show the voltage and amperage rating needed.
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