External floppy port does not work, A2000. Anyone know what to check for?

[Pat the Cat]

50-50 chance I reckon. 3.3V regulators do odd things with floaty grounds.

I'm not convinced having a separate power supply is a great idea for floppies. On an A2000 at any rate.

It's not like AmigaDos uses more than 2 floppy drives at a time, and that's just for copying a whole disk from one to the other. Generally only one is in use for reading. Depends how quick you eject and insert disks mostly.

As a rule of thumb, I turn on external expansions before powering up the Amiga.

External floppies going pear shaped can damage pull up resistors on the floppy circuitry. Usually the problems start by the power to the external floppy being shorted out with a different connector.

You have to allow yourself to make mistakes and learn from them with renovation.

Anyhow, if you start with getting DF0: internally working, you can use the external port to "snoop" on the different signals with a logic probe. In that case, having no power on the external floppy port actually works in your favor.

[Pat the Cat]

If you are having trouble finding replacement fuses, according to this;-

https://pmsoft.nl/amiga/amiga-parts-chips.html

You need 4A through hole pico fuses. Voltage not really relevant so long as over 12V. 125V frequently fitted.

(You can probably get away with 2A),

Nintendo fitted similar in the Gameboy, don't pay more than a buck each (hopefully less).

[Malakie]

50-50 chance I reckon. 3.3V regulators do odd things with floaty grounds.

I'm not convinced having a separate power supply is a great idea for floppies. On an A2000 at any rate.

It's not like AmigaDos uses more than 2 floppy drives at a time, and that's just for copying a whole disk from one to the other. Generally only one is in use for reading. Depends how quick you eject and insert disks mostly.

As a rule of thumb, I turn on external expansions before powering up the Amiga.

External floppies going pear shaped can damage pull up resistors on the floppy circuitry. Usually the problems start by the power to the external floppy being shorted out with a different connector.

You have to allow yourself to make mistakes and learn from them with renovation.

Anyhow, if you start with getting DF0: internally working, you can use the external port to "snoop" on the different signals with a logic probe. In that case, having no power on the external floppy port actually works in your favor.

I figured out how this happened.  I was using the unit just fine with the floppy gotek setup.   BUT I plugged a second gotek into the rear port forgetting it was one I got somewhere that has a cut off freaking connector that you have to make sure is moved to the side because it just has two pins cut off..  Was not paying attention and that was it.  poof.


Pisses me off though as I should have probably found a new connector instead of just trusting to remember to plug it in the right way due to this one was made for the external connector.

Going to order a new connector and replace the one on this other one so I don't do this again.


BTW, do you know a good source for parts like this or the fuses I will need to replace?   F4 is blown, F3 tests fine.

[Pat the Cat]

Mouser have if you can't find on Amazon. More expensive though.

Video, serial and joystick ports also have one each, so buying a bag of 10 isn't a terrible idea.

[Malakie]

Mouser have if you can't find on Amazon. More expensive though.

Video, serial and joystick ports also have one each, so buying a bag of 10 isn't a terrible idea.

Do you happen to know the actual part number for them on Amazon?   Not finding them.

[Pat the Cat]

If you search on

Pico fuse 4A

You will find them on amazon and eBay (Ebay might have a local supplier).

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313&_nkw=pico+fuse+4A&_sacat=0

https://www.amazon.com/s?k=pico+fuse+4A&crid=166G77NXHKM26&sprefix=pico+fuse+4a%2Caps%2C333&ref=nb_sb_noss

These links assume the buyer is in the UK (my point of view) rather than Michigan (your point of view).

But they are the American website stores.

[Malakie]

If you search on

Pico fuse 4A

You will find them on amazon and eBay (Ebay might have a local supplier).

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313&_nkw=pico+fuse+4A&_sacat=0

https://www.amazon.com/s?k=pico+fuse+4A&crid=166G77NXHKM26&sprefix=pico+fuse+4a%2Caps%2C333&ref=nb_sb_noss

These links assume the buyer is in the UK (my point of view) rather than Michigan (your point of view).

But they are the American website stores.

Holy crap, no wonder.. I was looking at the wrong amperage.   These boards pass up to 4 amps?  That's a lot of amperage for something like this.  I never knew that actually.  For some reason I was remembering 1 and 1.5 amp.

[Pat the Cat]

You don't HAVE to have floppies inside an A2000 at all. Plus, duplicating software can drive all four drives, even if the Os doesn't behave that way.

Not everybody uses the power pins on external ports for their intended use either.

[Pat the Cat]

Anyway, if you want to go 500 milli amp (still overkill);-


https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313&_nkw=pico+fuse+500&_sacat=0&LH_TitleDesc=0&_odkw=pico+fuse+4A&_osacat=0

EDIT: Better go 1 Amp, tech reference manual reports surge current of 540mA.

https://www.opweb.de/english/company/Commodore/Amiga_A2000

(Amazon too screwy, started mixing in 500 Amp fusss).


You might consider fitting a thermal cut off fuse instead. They don't blow, they just shut off with an over current (more recent technology than pico fuse).