FSE 5.25" Drive

[sb1903]

Hi,

in the attic I found our old FSE 5.25" drive (see https://www.cpcwiki.eu/index.php/Frank_Strauss_Elektronik). I am wondering what is the right adapter to power it. In the same attic, I found an Amstrad power adapter with 6V / 300mA output that I suspect may be the original power adapter, but I am unsure. 6V sounds like a quite odd voltage, I would have expected either 5V or 12V. Does anybody of you have an idea if this 6V could be correct or what would be the right voltage. Since the drive looks good from outside and I know it worked "til then end" when we stopped using the CPC, I really don't want to blow it now by powering it with the wrong voltage.

This leads me to the next question: I wonder if I can connect this drive to my Greaseweazle v4 without having to worry about termination (as described on https://github.com/keirf/Greaseweazle/wiki/V4-Setup#drive-terminations)? I would assume the drive has the right terminator already, or is it rather unlikely given that it was drive B on the CPC?

Thanks!

[Bryce]

Any chance that the 6V adapter is AC and not DC? If that's the case it may actually be the correct adapter, but don't connect it until you are absolutely sure. I don't know that particular drive, but opening it up and posting a picture of the additional electronics inside would help a lot.

Bryce.

[sb1903]

Thanks, Bryce. It says "DC output", so probably it's the adapter for something else then. I have universal adapters at home. But would be helpful to know what is the right voltage to configure them to.

[sb1903]

I have opened the case of the drive. This is how it looks inside.

[sb1903]

and from the other side:

[SerErris]

You can power it with a typical +5V +12V drive cable. So if you have an ATX power supply, you can use that.

From the "PowerSupply" it looks like it has been powered with a 12V DC power adapter and created internally a +5V voltage via a linear voltage regulator.

You cannot view this attachment.

However there are two of them. If you can get a photo from both of those so that we can read the type of them, that would help. 

I am currently scratching my head, why they have two power regulators AND an external power supply. That does not make to much sense other, they had a non stable power supply and regulated it with another Lineare 7812 or something. But for that another large capacitor is missing...

So for sure that is a totally normal power connector on the drive itself and the power supply can be replaced with any powersupply for drives.

Or you just help us to reverse engineer the powersupply and we can tell you what external powersupply will work here.

[sb1903]

I actually should have a spare ATX power supply somewhere. So you say, I can simply ignore the power connector of the case with that additional circuit of linear regulators, and instead I power the drive directly with the ATX power supply to the drives' molex socket. That actually sounds like a good idea!

I can open the case again later today and take another picture if you want.

[sb1903]

Here two pictures of the power supply circuit. Does that help?

[Bryce]

Ok, great pictures. That PCB has regulators for the 5V and 12V rail. The L7812CV is the 12V regulator and that has a dropout voltage of 2.5V. That means that the input voltage needed to be at least 14.5V for it to work reliably. So it most likely originally had a 15V or 16V supply (DC). The Negative should be on the outer ring and positive on the inner ring of the connector.

Bryce.

[SerErris]

If you want to use this power supply, you should replace the Elco and also renew the thermal paste between the aluminium chassis and the linear regulators. This is most likely dried and not doing its job anymore. 

And yes, you can just ignore the whole powersupply and connect the Molex Plug from your ATX power supply. However you also need to bridge certain pins on the ATX power supply to activate it. Otherwise it will not provide any power on the 12V or 5V rails.

[sb1903]

Thank you @SerErris and @Bryce. I will most likely go for the solution with the ATX power supply. Connecting these two pins on the motherboard connector to ensure the power supply works without a motherboard, shouldn't be a problem

Do you have an opinion with regards to termination of the drive? I still wonder if this is something I need to bother about or not.

[SerErris]

This should be the schematic of your PS.

I could not identify the value of the large capacitor, but that should be pretty much accurate.

You cannot view this attachment.

[SerErris]

Hi,

I also think, that this is already terminated.

There is a resistor network directly close to the connector, which is normally the termination you are looking for.

I just would give it a try. It cannot damage the drive if you attach it to the greaseweezle

But why do you want to attache it to a greaseweezle? You should connect it to your CPC of cause :-D

[SerErris]

I do have one of those for my kryoflux:
https://www.ebay.de/itm/164460996215?hash=item264aa3a677:g:VzMAAOSw3C5fj-YY&amdata=enc%3AAQAIAAAA4J6%2Fe3zviuY20iofCAy%2BBkjOe0LIc5kO8Pdsrga9sS7M2MFmos2QRFNVP7xtsx1RcvvFyBJHUzN2fiOjdycr9wo19TW95MfBMKp%2BCKDW1HcVHMiAdrTozBhBYA6pL6SEDgbJtmdz7m%2FcLKwXR99wx72AOcZ1QDeX53vQHaGP1xEF8wKO5lSVEKMAo9NEMKXhoXHQlPOkdRgLJ8XpjUxWQKYOvHygwg6%2FVpjXte5r9SN9VOFv0UBMtSrZu%2Fr7IApo%2FVQWhpMf28Zvc2LOA02YxcauMEqqRl9FPFDjMvNGj1ZE%7Ctkp%3ABFBM6pjP_Opi

Not sepcifically this one, but I think they all do and should be much better than an ATX power supply, that is pretty much overpowered for the job :-)

But if you have one, the ATX power supply is obviously faster to use for your lab.

For the actual usage of the drive, I still would use the external DC power supply. However you can massively simplify the design.

connect the 12V rail directly to the drive and just use the 7805 for the 5V rail. You could then use a direct 12V power supply, which is very easy to find.

So just disconnect the yellow cable from the barrel connector and wire a new one to the capacitor shown in this diagram and you have rebuild it to 12V supply. 

The only thing is, that you have no elco in the power supply part anymore, but that should be covered by the powersupply itself and much better probably. 

You cannot view this attachment.

[sb1903]

But why do you want to attache it to a greaseweezle? You should connect it to your CPC of cause :-D

True   The purpose of this exercise is to read in a couple of 5.25" disks with software (some self-written in Basic) and data and get them converted into DSK format, so I can access them with any modern PC with any CPC emulator. I did the same already with all my 3" disks, which worked like a charm.

[SerErris]

So for real operation you either want to mod it to 12V supply or to restore it properly (as mentioned above) and with an external specific supply. I personally would opt to rebuild it to the original state as much as possible, to conserve it as far as possible in its original state.

I have done the same with the Vortex F1-X drive. I needed to exchange parts, but kept the functional design.