- VCF Southeast - July 19 - 21, Atlanta, GA
- VCF West - Aug 2 - 3, Computer History Museum, Mountain View, CA
- VCF Midwest - Sept 7 - 8 2024, Schaumburg, IL
- VCF SoCal - Mid February 2025, Location TBD, Southern CA
- VCF East - April 2025, Infoage Museum, Wall NJ
-
Please review our updated Terms and Rules here
I have joined the Osborne 1 club today.
- Thread starter Klee
- Start date
KennyPowers
Member
- Joined
- Jun 16, 2021
- Messages
- 33
Once you get it running, verify the RPMs of both disk drives before you put it back together. You can check the speed using the strobe wheel on the drive, and adjust the speed with the trimpot at R23.
The power supply tests out good even with the swollen rifa caps.
Tested it without any load on it.
Output pins:
+5.05v
Ground
+12.05v
-11.5v
So just waiting on the new ones.
Next started to do some simple tests on the main board with a multi-meter.
Immediately found that there was a 12v direct short to ground, all the caps looked physically ok so I decided to remove cap C71 because its easy to get to and I watched a youtube video of someone diagnosing a short on a Osborne 1 and thought I had to start somewhere and since his C71 cap was the problem I might as well remove it.
That fixed it, no more short from 12v and tested the cap and it was shorted internally.
So making progress.
Tested it without any load on it.
Output pins:
+5.05v
Ground
+12.05v
-11.5v
So just waiting on the new ones.
Next started to do some simple tests on the main board with a multi-meter.
Immediately found that there was a 12v direct short to ground, all the caps looked physically ok so I decided to remove cap C71 because its easy to get to and I watched a youtube video of someone diagnosing a short on a Osborne 1 and thought I had to start somewhere and since his C71 cap was the problem I might as well remove it.
That fixed it, no more short from 12v and tested the cap and it was shorted internally.
So making progress.
Last edited:
Yep that is on the agenda.
I am going to take my time on this computer since its too nice to not make it as nice and smooth running as possible.
I just took the pc board off the A floppy drive to check out the internals and to lube the rail and drive worm screw.
The read head is perfect, shiny with ZERO scratches or marks.
I tried to take a couple of pics but they just do not show how perfect the read head is, i'm starting to think this Osborne has never been used, I am starting to believe it was NOS in the box and I'm guessing that sometime before I got it someone took it out of the box and tried to power it up and it would not because of the shorted C71 cap and took it apart and put it back together without fixing it or using it.That would explain the labels all in it.
The round circle is the shadow of the upper arm that drops on top of the floppy to keep it on the read head and shows how smooth it is.
I have had a lot of used 5.25 drives and none are anywhere close to the condition of this drive.
The guide rail has zero marks on it with just a few specks of dust, the worm drive is also perfect.
LOL there is zero cleaning needed, all I did was lube the worm and guide rail.
The read head is perfect, shiny with ZERO scratches or marks.
I tried to take a couple of pics but they just do not show how perfect the read head is, i'm starting to think this Osborne has never been used, I am starting to believe it was NOS in the box and I'm guessing that sometime before I got it someone took it out of the box and tried to power it up and it would not because of the shorted C71 cap and took it apart and put it back together without fixing it or using it.That would explain the labels all in it.
The round circle is the shadow of the upper arm that drops on top of the floppy to keep it on the read head and shows how smooth it is.
I have had a lot of used 5.25 drives and none are anywhere close to the condition of this drive.
The guide rail has zero marks on it with just a few specks of dust, the worm drive is also perfect.
LOL there is zero cleaning needed, all I did was lube the worm and guide rail.
Last edited:
The B drive.
Amazingly clean inside.
This pic shows how smooth the read head is, I could not get it to focus on the head it would only focus on the reflection.
The above pic is the best I could do, the 45 degree "line" just to the left of the white area is not a scratch but a reflection of the hold down arm as I was holding it away from the head.
Amazingly clean inside.
This pic shows how smooth the read head is, I could not get it to focus on the head it would only focus on the reflection.
The above pic is the best I could do, the 45 degree "line" just to the left of the white area is not a scratch but a reflection of the hold down arm as I was holding it away from the head.
