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General Category => Amstrad CPC hardware => Topic started by: cpcitor on 19:52, 01 June 17

Title: Powering a CPC with a FD-1 power supply?
Post by: cpcitor on 19:52, 01 June 17
Hello.

I have a CPC 464, a DDI-1, a FD-1 and a CPC 6128.
The FD-1 is damaged though it could be recovered (unsure) -- perhaps more damage that broken belt and lost write pin.
Perhaps it's dead but the power supply is perfectly fine.

Trying to repair disc drives I saw the 4-wire power connector at the back of the 3" drive inside the FD-1 box.
Such connectors look like PC-style floppy drive power supply.
I checked the voltage on these pins: 5, 0, 0 12 (in CPC 6128 actually).
Voltages are unsurprising, but ... in the case of a FD-1 those voltages come from the FD-1 power supply.

So, the FD-1 can provide +5V and +12V.

This yielded an idea: could the power supply inside the FD-1 case power a whole CPC ?

I can see two options!

(1) Power a CPC-464. With the hack (extra wire) described in http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/ddi-1-conversion-for-use-without-an-fd-1/msg22724/#msg22724. Pro: solder one wire. Simple, clean. Con: modified DDI-1 cannot/should not (or can it safely?) work on an already regularly powered CPC-464, as already discussed there.

(2) Power a CPC-6128 or a 464. Make an adapter cable from the 4-wire power inside the FD-1 case to provide two external plugs that plug on the regular CPC-6128 power.

One question remain: CPC sucks extra power, can the FD-1 power supply handle that ?

Comment welcome. Thanks.
Title: Re: Powering a CPC with a FD-1 power supply?
Post by: cpcitor on 19:53, 01 June 17
Hey, it was my 129th post. I should have made a party for the 128th  :picard:  :laugh:
Title: Re: Powering a CPC with a FD-1 power supply?
Post by: gerald on 20:24, 01 June 17
According to the DDI1, the power supplies are regulated by one L78N12 and two L78N05 (one for the drive, one for the interface), all able to provide 500mA
A 464 with 40007 GA consume about 900mA on the 5V rail when idling and in the range of 1.1A while reading a tape.

Even having both 5V in parallel (not recommended), it won't be enough.
Title: Re: Powering a CPC with a FD-1 power supply?
Post by: cpcitor on 17:14, 08 June 17
Thanks @gerald (http://www.cpcwiki.eu/forum/index.php?action=profile;u=250) for the informative answer.

This is confirmed and even worsened by Power Supply for CPC and CPC plus - CPCWiki (http://www.cpcwiki.eu/index.php/Power_Supply_for_CPC_and_CPC_plus): 2A for CPC464, 1.7A for CPC664 and CPC6128.

They might have kept some safety margin, anyway it's much more than 0.5A that L78N* can provide.
Topic solved.


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