This disk is unreadable

[nvdeynde]

Most of the time the Bourns filter of the Floppy drive goes bad due to a bad FDD cable/drive or a loose connection.

I killed one a while ago on an SE board because the cable of the floppy drive was not plugged in 100% and so not all pins made connection.

I got the "Disk unreadable, Eject/Initialize" error upon next boot but it was already too late: the bourns filter of the FDD was gone.

Changing the filters together with the capacitors in not necessary. You can test the Bourns filters and if they are still good, leave them as in the end they are not exactly cheap. They don't go bad without a cause.

 

[uniqueidentity]

Thanks for that. I'll get the electrician to check them for me - I've got the wiring diagram for them. I was lead to believe they can expire like caps? I think we're lucky here in the UK as RS stock the filters for £3ish each, and we have an account with them at work where we get a discount and I can save on the delivery costs.

 

[phreakout]

One thing I can say on this, if the drive is bad, you can swap it out for one out of pretty much any other Mac model with a floppy SuperDrive. The only drawbacks are that the newer models used floppy drives with manual injection, plus you might have to modify the front plastic bezel if the slot for the disk doesn't line up perfectly.

I do have a copy of the entire SE/30 schematics, but it's on the server at home. Let me get there and I'll post an update of my trace.

73s de Phreakout. :rambo:

 

[uniqueidentity]

I haven't tried another floppy, but I believe the one I have is actually from a Classic II as the one that came with the SE/30 didn't work (or I didn't trust it).

Thanks guys for all your help.

 

[nvdeynde]

I haven't tried another floppy, but I believe the one I have is actually from a Classic II

All Superdrives in the Compact Mac series, from an SE FDHD to Color Classic, are identical.

Once the Bourns RP is gone, changing the floppy drive is too late...

I would buy a few spare Bourns filters as if the floppy drive or cable is the problem, the new chip will be gone almost instantly.

It's probably a good idea to solder an IC socket on the PCB for the Bourns RP so it can be easily exchanged.

 

[uniqueidentity]

I can't work out which IC socket I would need. The chip is here: http://uk.rs-online.com/web/p/rc-network-capacitors/6909903

Any ideas?

 

[phreakout]

Okay. Some of this may be a bit backwards, but I was able to trace through to what parts make up the floppy portion of the SE/30. Here it goes:

- J6 (external 19-pin connector) links up to F2 (fuse, 1A), C51 (capacitor, 0.01 mF? uF?), C52 (capacitor, same as C51), L16 (inductor, unknown value) and L17 (inductor, unknown value).

- J6 also links up with R30 (resistor, 22 K-ohm? 22-ohm?), C67 (33 pF), RP10 (Bourns network filter), J8 (internal floppy connector), L22 (inductor, unknown value), UJ11 (SWIM chip), L21 (inductor, unknown value), UI12 (53C80 SCSI Controller Chip), L8 through L10 (inductors, unknown value), C47 (capacitor, same value as C51), D3 (diode, 1N4001), F3 (fuse, 1A), J4 (External SCSI connector) and J5 (Internal SCSI connector).

I've included a page of the schematic. I hope that's okay with the mods. If not feel free to omit. It was posted a while back to this site, so I figured it is safe to repost.

73s de Phreakout. :rambo:

 

[techknight]

ive seen this on several occasions, the bourns network matching filter is the culprit usually. the SWIM rarely goes bad, you would literally have to do something WAY wrong to fry it.

 

[Dennis Nedry]

I can't work out which IC socket I would need. The chip is here: http://uk.rs-online.com/web/p/rc-network-capacitors/6909903
Any ideas?

Not having seen the actual parts, this looks like an ordinary DIP socket to me.

 

[uniqueidentity]

phreakout: That's amazing. I can pass that on to the electrician so he can trace he problem. Thanks!

techknight: That's very good news - it means I'm not wasting my time. Excellent.

Dennis Nedry: The RS website has so many DIP sockets and to my untrained eye I couldn't see one that looked right. (P.S. Like the website)

Once I get the SE30 I won I'll get these bits off to the electrician. He should be able to work out the IC socket.

Ant

 

[uniqueidentity]

phreakout: Just noticed the floppy connects to the SCSI controller? I wonder why?

 

[phreakout]

I think it's because both technologies are actually serial devices. One important hint to pass on: If you completely remove the Bourns network filter (or equivalent) off of the logic board, it disables the external floppy port and the internal still works. The same goes with the network filter for the SCSI side.

If you need more schematics for the whole blasted thing, let me know.

73s de Phreakout. :rambo:

 

[onlyonemac]

Umm... no one seems to have asked. Is he actualy using an external floppy drive? If he is, then the reason it's flashing on and off is most likely a faulty/dirty cable. If he's not using an external floppy drive, then I'm not clued up enough to suggest anything. I really don't know about these compacts.

 

[uniqueidentity]

You're right - I didn't make it obvious, but no - I'm not using an external floppy.

I'm confident once the filters are changed the problem will be resolved. Am waiting for a quote.

 

[techknight]

if it pops up randomly and nothing is connected, its for sure the bourns network.