Re: Daisy Wheel Printer repairs

After some more test printing I discovered another problem.. the hammer was sticking. Upon taking it apart I found the spring inside was broken. The parts printer gave up some more useful pieces: https://lh3.googleusercontent.com/-dlVgHJDZRrQ/VaFhv-igA1I/AAAAAAAAHtU/61dbeC4oGUg/s576-Ic42/IMG_20150709_223358.jpg

As noted in the Lisa FAQ, the default dip switch settings on the DMP are not correct for use with the Lisa. The default setting is space parity, no modem, ETX/ACK & DTR handshake, 1200 baud. The printer needs to be changed to 9600 baud. This is set on dip switch 1, the top of the printer must be removed to access it.
https://web.archive.org/web/20120418205712/http://lisafaq.sunder.net/lisafaq-hw-prn_daisy_dips.html

Another discovery I made: The printwheels are very fragile. Several of the pins on my Prestige Elite 12 wheel are slightly bent, possibly from the sticking hammer issue I noticed earlier. This leads to misaligned characters.

PS: Here's a comparison between the Apple printwheel and the Qume / Xerox Diablo printwheels:

https://lh3.googleusercontent.com/-FzQ4-IYhmzU/VaFhvy7dqaI/AAAAAAAAHtc/UDvPigO-2WY/s640-Ic42/IMG_20150709_223849.jpg https://lh3.googleusercontent.com/-7q7H5SE3cZo/VaFhvw2aA2I/AAAAAAAAHtU/heZ3BAyJ3k4/s1024-Ic42/IMG_20150709_223747.jpg

And yes, the DWP can produce graphics. There is a metal pin on the printwheel used for this. It's quite slow, but does work. I'll make a video of this later.

Thanks,

-J

On Wed, Jul 8, 2015 at 10:17 PM, Jason Perkins <perkins.jason_at_email.domain.hidden> wrote:

> James was exactly right. The two white wires go to the bottom two contacts
> on the switch.
>
> The motor from the newer Qume printer works perfectly in the Apple DMP. It
> seems the board which drives the printwheel died... no problem since the
> one from the Qume worked.
>
> I was able to print some nice barber poles out... quite exciting for me
> anyway since I've had this printer for almost 10 years and it has never
> worked.
>
> https://www.youtube.com/watch?v=JTk-HD_sZN0
>
> Now the only remaining steps are to tidy up the wiring, put the case back
> together, and try and print some graphics :)
>
> Thanks,
>
> -J
>
> On Wed, Jul 8, 2015 at 1:18 AM, compu_85 <perkins.jason_at_email.domain.hidden> wrote:
>
>> Both the black and red wires have capacitors on them, which connect to
>> the chassis ground. I'm guessing these are for noise suppression... the
>> Apple branded printer had tons of extra ground straps running all over the
>> place, and some extra shielding the Qume branded printer didn't have.
>>
>> Perhaps what is making me doubt my pictures is that the Qume branded
>> printer had the motor connected through the microswitch. Perhaps this is
>> why I didn't take detailed photos of the Apple branded printer... the black
>> and red wires hook to the black and red terminals on the motor and the 2
>> white wires go to the switch.
>>
>> To get at the black terminal on the motor the chassis has to be removed.
>> But I should be able to do a test without bolting the whole machine back
>> together.
>>
>> Another difference between the Qume and Apple branded printers: The
>> control / amp board for the sensor on the motor is attached to the motor on
>> the Qume printer, on the Apple printer it is on a socket on the logic
>> board. The socket header is the same on both though, I'm guessing this was
>> just a manufacturing update that happened between 1983 and 1993.
>>
>> Thanks for the suggestion James, I think it helped jog my memory.
>>
>> -J
>>
>> On Tuesday, July 7, 2015 at 10:48:15 PM UTC-4, James MacPhail wrote:
>>>
>>>
>>> >Here's some links to high res pictures I took. I can't tell where
>>> >the red wire should be going... in one photo it looks like it goes
>>> >right to the motor, in another it's plugged into the switch. Perhaps
>>> >I misconnected it somewhere along the way?
>>>
>>> Hard to tell for sure from the two photos, but:
>>>
>>> 1) It looks like the switch is a simple/common SPDT "microswitch"
>>> (brand). If so, and depending on its function, it is highly unlikely
>>> that more than two of its terminals would be connected. ie. the
>>> controller would want to know when the switch changed state, and it
>>> only needs two wires to do that.
>>>
>>> 2) It looks like the red wire also has a capacitor wired to it. That
>>> would be for interference suppression, and normally isn't required
>>> for a switch that operates intermittently, but quite possibly be
>>> needed for a stepping motor.
>>>
>>> 3) It looks like the motor doesn't have any other wires connected to
>>> it...
>>>
>>> So I vote for "should be connected to the motor", but you could try
>>> powering it up with the wire disconnected and see if you get any
>>> information from the behaviour.
>>>
>>> Good luck!
>>>
>> --
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>
>
>
> --
> Jason Perkins
> 313 355 0085
>

-- 
Jason Perkins
313 355 0085

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