The display tells you that a startup disk or drive can not be found. The Mac Plus that I owned had an external SCSI connection hard drive (20MB) that I could use as a startup after installing Mac OS 6.0.3. Many of these could be run with limited software from a HD floppy. You probably need to acquire a set of System instllation disks.
Below are some sites that may have a source or some better ideas than what I have given. The Machine looks great so I hope you can get it up and running.
This is a direct link for System 6.0.x from Apple:
Depending upon the amount of RAM installed, System 6.0.3 or 6.0.8 can be used (see the text files). Please note that a Macintosh Plus is limited to working with 2DD/DSDD diskettes in the special Macintosh format 800K. Access to another older (pre-1998) Macintosh computer (with a built-in floppy drive, and StuffIt Expander for the decoding) is needed in order to create floppies from downloaded files (use Disk Copy 4.2).
An Apple User Group could possibly be of help:
In the photo it looks like you have a hard drive; is it connected to the SCSI port? Is it ON when you power-up the Plus? Is it terminated? Does it have a system installed on it?
If it needs to be re-formatted, you will need the System Tools floppy disk.
The Plus WILL start-up from the System Tools floppy, as others in this thread have mentioned.
It seems to me that I have got the same problem with my old MacPlus which has been sitting in the back of the cupboard for yonks. Hard-drive light is green, but the Mac does not seem to recognise it. Everything seems to be connected correctly. I don't have the original software disks anymore and only put it on to see if the originial laser printer that came with it is still working. Any ideas?
It looks like your external hard drive is NOT an Apple-branded hard drive; to format it you will need to patch the utility Apple HD Setup.
The patch is a Godsend. It really works.
Here is the link:
Once you have formatted it, it will be recognized by your Mac. Install a good system on it and you'll be in business.
I'm guessing that these Macs worked originally.
In the first photo I don't see a power light on the external hard drive, is it plugged in and turned on? If yes is there a SCSI terminator on the unused connector on the back of the drive.
In the other photo, could likely be that over time the hard drives heads got stuck. Do you hear the drive actually spinning? If not try very very gently swishing the drive from side to side, this sometimes will unstick the heads/platters. Do not violently shake it! In a really worse case scenario a clean room and a popped hard drive cover and a manual spin up can get it going long enough to recover the data but the drives are typically not reliable at that point.
Buying a used SCSI drive can also be a bit of a crap shoot at this point since it could also be on it's last legs.
Nightshooter asked a very important question. Do you hear the hard drive starting up? It will make a noise like an airplane engine starting up. There is another way to wake up an old hard drive. Take a plastic handled screwdriver, hold it vertically by the metal tip and gently drop the plastic handle onto the screw that is the center spindle of the drive. That may jar the platters and free up the 'sticky grease' that is no longer lubricating the spindle. This method allows you to leave the drive intact. In order to do this, you must open up the plastic case --- but do not open the metal hard drive itself --- to see the hard drive and which nut holds the spindle.
Keep in mind that the original hard drive management software did not automatically park the heads. You specifically instructed the hard drive to 'park heads' every time you wanted to move your computer and/or external hard drive, just to be safe. If the drive heads are parked, they are off to the side of data blocks that matter. If the heads are not parked, they could damage a sector on the platter. That is why being gentle is important. The soft drop approach directs the energy exactly where you want it. Vertically on the spindle.
First check for the airplane engine noise and post back. If you are familiar enough with hard drives to understand the paragraph above, great. Otherwise, find a discarded PC that no one cares about, remove the hard drive from it, take that drive apart for the education, and then check back for further instructions.
The device we used in the shop for working on multiple macs was an external zip drive. Each zip disk would have a different OS. That way you could test drive an OS and optimize your computer for the nicest operation for the RAM you have before installing any updates to the hard drive you have.
Then check back with your progress.