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General Category => Technical support - Hardware related => Topic started by: CPC_FREAK_BELGIUM on 20:30, 07 October 23

Title: Can a CPC 664/6128 be powered thru a USB port.
Post by: CPC_FREAK_BELGIUM on 20:30, 07 October 23
Hello Folks

I have some questions about using a CPC without the original monitor. Special cables are available to connect the CPC to an LCD screen.

The problem is the power supply, my question is whether a CPC664 can be powered thru a USB port. 

I would like to use the items below for this and was wondering if anyone has experience with this.

-https://www.aliexpress.com/item/1005005124774428.html
-https://www.aliexpress.com/item/1005004118413025.html (this requires the polarity to be reversed if I'm not mistaken)
-https://www.aliexpress.com/item/1005005058325558.html

Thank you in advance.

Greetings from Belgium

CPC_FREAK_BELGIUM
Title: Re: Can a CPC 664/6128 be powered thru a USB port.
Post by: Ynot.zer0 on 21:57, 07 October 23
I believe the motherboard can be powered by 5v, not sure how many amps, usb is usually 2, should be okay. However, the disc drive needs 12v.

There is a guy who will sell you an all in one PSU that powers the machine and the disc drive - I use that cable myself.  You can get them from cool-novelties on ebay, that would be your best option

www.coolnovelties.co.uk/coolnovelties
Look under retro computers and amstrad cpc
Title: Re: Can a CPC 664/6128 be powered thru a USB port.
Post by: SerErris on 01:40, 08 October 23
USB is defined as 0.5 A per port, without any additional negotiation. USB C and esp. USB 4 can deliver massively more, but not with 5V. I think with 5V it is limited to 3A.

Anyhow that requires negotation between the USB port and the Receiver, so the "power supply" would need to singal that it can pull 3A. 

Not every USB port thos does support higher output than 0.5A.

So it depends.

A 664 can anyhow never be fully powered by USB as it requires 12V for the disk drive. Only a modded 664 can be powered (e.g. gotek) by USB.

The stepup converter will not make it better. It can still only deliver max 15w ... for 5V that is 3A .. but for 12V that is only 1,25A ... and if you reduce the 1.5A the CPC needs from 5V rail only 0,58 A is left for 12V rail. 

That would be not enough and actually I do not think it is a good idea at all.

Better look for a power supply with two voltages (12V and 5V) and put the correct connectors on, or buy it ready.

Like this one:
https://www.ebay.de/itm/324218253955?mkevt=1&mkcid=1&mkrid=707-53477-19255-0&campid=5338328878&toolid=10029&customid=16967256115610046595915511119008005

Title: Re: Can a CPC 664/6128 be powered thru a USB port.
Post by: poulette73 on 06:46, 08 October 23
Quote from: SerErris on 01:40, 08 October 23Like this one:
https://www.ebay.de/itm/324218253955?mkevt=1&mkcid=1&mkrid=707-53477-19255-0&campid=5338328878&toolid=10029&customid=16967256115610046595915511119008005
👍

This is exactly the model that I have owned in 2 specimen, for my 2 CPC 6128s, for several years.

No problem at all, I highly recommend it.
And it's powerful enough to use any expansion card on the CPC, without having to externally power a Mother X4 containing multiple expansions.
Title: Re: Can a CPC 664/6128 be powered thru a USB port.
Post by: fgbrain on 18:42, 08 October 23
Title: Re: Can a CPC 664/6128 be powered thru a USB port.
Post by: GUNHED on 22:33, 08 October 23
Yes, it only needs 5 Volts and 2-3 Ampere. Better 2-4 with expansions.
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