Macintosh Plus 800K Floppy drive circuit

[Mikemike690]

I opened the floppy drive to clean and I noticed that the little circuit board on the photo below was snapped? Is there anyway to either replace or fix? Thanks.

http://imgur.com/rrrbgZv

 

[Elfen]

Crazy glue the pieces together and solder jumper wires from point to point following the traces. 3 wires at most.

Somehow you broke the Track Zero Sensor. Simple fix!

 

[Mikemike690]

Haha you don't wanna know how I broke it! Anyway it has three wires going to four terminals, how do you suppose I split it? Thanks.

 

[Elfen]

One wire is ground, so just connecting one should connect it to the other side. The other two you follow to where they have to go.

I've broken those things many times, so I can imagine how it happened to you. Does it involve rabid hamsters? Never mind.

 

[Mikemike690]

So the one that goes to two terminals is ground? Here's a picture

http://imgur.com/IXvo0cw

 

[Mikemike690]

Just finished wiring it, I don't know if all the connections are good, but now it's like rattling/clunking even without a disk, what is causing this?

 

[Elfen]

The brown (middle wire) is the ground of the circuit. See how the wiring is supposed to be:

Be careful to not to solder spill or bridge between the two points on each sensor part. The space there is very tight so take your time doing this repair.

You should also glue the broken piece back in place. Looking at how it broke, it should fit like a loose puzzle piece.

 

[bibilit]

If wires are long enough, it will be possible to desolder from the broken piece and solder directly to the remaining part... just my two cents..

 

[Elfen]

Unfortunately, they are not long enough. Two might be able to be stretched to do this on the top of the sensor but not the bottom (3rd) wire. Sometimes I why Apple does this. It's designed for that if you break it, you have to replace the whole sensor with the wiring harness, not do a hack to fix it.

Edit: Looking at my 800K drive (again), if rewired as stated before like you said, the the floppy arm that goes into that sensor would be hitting the wire if you stretched  to be soldered in place which would cause interference.  Damn it. But great idea though.

 

[Mikemike690]

Okay so I've fixed the wiring, booted the computer, and it's not clunking, but as soon as I insert a disk it rejects it and has a X floppy disk icon. Any ideas?

 

[bibilit]

Dirty head ?

 

[Mikemike690]

Yeah possibly I'll let you know in a couple days. Thanks.

 

[techknight]

if the stepper motor gets twisted or bumped, it will change the track alignment. 

 

[Mikemike690]

if the stepper motor gets twisted or bumped, it will change the track alignment.

Oh, is there any way to realign it? Because a drop actually broke that board. Thanks.

 

[techknight]

Yup, its been knocked out of alignment, and probably not repairable. 

You need to grab a known good bootdisk, and loosen/turn the head stepper motor until it eventually detects the disk and boot. 

Hell, the old sony mavica floppy digital cameras, you could drop it 6 inches and knock those fuckers out of alignment. 

 

[Mikemike690]

Haha, that would be a pain, anyway I've contacted my local computer store to see if they would be able to realign them. What did you mean not repairable?

 

[techknight]

because its really difficult to get the alignment exactly right. To do that, you need a reference disk and an oscilloscope. 

 

[Mikemike690]

Oh, couldn't I just turn the motor until it reads?

 

[techknight]

yea but your talking about millimeter adjustments. maybe half a mil. 

You can, but itll never be 100% exact. 800K is much easier than 1.4MB though. 

You may get it by luck though, cant hurt to try!