1 Feb
2024
1 Feb
'24
11:26 a.m.
The drive works perfectly for double sided disks (using the
appropriate index hole).
Yea, 8" drives are a bit funny like that.
You know this, because context. Some future google-ologist might not.
So. 8" drives have a different index position for SS and DS.
In your case I suspect either the emitter LED or the receiver
phototransistor ro maybe the wiring or what ever conditioning on the
PCB is b0rken for the SS sensor.
Assuming of course your drive has two sensors -- I have not yet owned
an 8" drive like that, the ones I have had were dedicated SS or DS.
W
1 Feb
1 Feb
12:42 p.m.
New subject: Qume 842 8" Disk Drive Question
The drive has 2 index sensors. I've never seen a double sided 8" disk
drive that couldn't read a single sided disk because it didn't have the
single sided index sensor.
On 2/1/2024 1:26 PM, Wouter de Waal via cctalk wrote:
The drive works perfectly for double sided disks (using the
appropriate index hole).
Yea, 8" drives are a bit funny like that.
You know this, because context. Some future google-ologist might not.
So. 8" drives have a different index position for SS and DS.
In your case I suspect either the emitter LED or the receiver
phototransistor ro maybe the wiring or what ever conditioning on the
PCB is b0rken for the SS sensor.
Assuming of course your drive has two sensors -- I have not yet owned
an 8" drive like that, the ones I have had were dedicated SS or DS.
W 
2:51 p.m.
New subject: Qume 842 8" Disk Drive Question
On 2024-02-01 4:42 p.m., Mike Katz via cctalk wrote:
The drive has 2 index sensors. I've never seen a
double sided 8" disk
drive that couldn't read a single sided disk because it didn't have
the single sided index sensor.
A double sided drive that can read single sided diskettes has to have
two index sensors as the index hole is in different locations on a
single sided diskette than on a double sided diskette.
Paul.
3:37 p.m.
New subject: Qume 842 8" Disk Drive Question
Agreed, that is the crux of the entire thread. The Double sided sensor
is working and for some reason the single sided sensor isn't generating
the index pulses.
The original question was put out here to see if someone knew of a
jumper that I missed in the service manual.
The comment you were replying to was me responding to someone else. They
said they had seen double sided drives that did not have the extra
sensor and I said I had never seen that.
On 2/1/2024 4:51 PM, Paul Berger via cctalk wrote:
On 2024-02-01 4:42 p.m., Mike Katz via cctalk wrote:
The drive has 2 index sensors. I've never
seen a double sided 8"
disk drive that couldn't read a single sided disk because it didn't
have the single sided index sensor.
A double sided drive that can read single sided diskettes has to have
two index sensors as the index hole is in different locations on a
single sided diskette than on a double sided diskette.
Paul.
12:50 p.m.
New subject: Qume 842 8" Disk Drive Question
On 2/1/24 11:26, Wouter de Waal via cctalk wrote:
2 8" index sensor drives are common as dirt. Basically, if a drive is
double-sided, it will have two sensors. Many also include a status
output that indicates which sesnor is operational.
--Chuck
The drive works perfectly for double sided disks (using the
appropriate index hole).
Yea, 8" drives are a bit funny like that.
You know this, because context. Some future google-ologist might not.
So. 8" drives have a different index position for SS and DS.
In your case I suspect either the emitter LED or the receiver
phototransistor ro maybe the wiring or what ever conditioning on the PCB
is b0rken for the SS sensor.
Assuming of course your drive has two sensors -- I have not yet owned an
8" drive like that, the ones I have had were dedicated SS or DS.
109
days inactive
109
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4 comments
4 participants
participants (4)
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Chuck Guzis -
Mike Katz -
Paul Berger -
Wouter de Waal