Service manual for 1520 plotter

[Fergus Logan]

Is there such a thing as a service manual for the 1520 printer plotter, or
the Alps plotter mechanism?

I have 2 of these beasts, both with the same problem; the paper feed slips.
On the right hand side of the mechanism, the cog that is attached to the
platten seems to have a spring that has come loose. This cog has two wheels
to it and appears to be some sort of clutch mechanism. does anyone know how
the cog should look with the spring in the correct place?

Kind Regards,
Fergus.

[Charles Richmond]

Post by Fergus Logan
Is there such a thing as a service manual for the 1520 printer plotter, or
the Alps plotter mechanism?
I have 2 of these beasts, both with the same problem; the paper feed slips.
On the right hand side of the mechanism, the cog that is attached to the
platten seems to have a spring that has come loose. This cog has two wheels
to it and appears to be some sort of clutch mechanism. does anyone know how
the cog should look with the spring in the correct place?

Radio Shack sold this same mechanism in a pen plotter of theirs.
I know that RS had a maintenance manual for their plotter, and you
may still be able to order it through them.

--
+----------------------------------------------------------------+
| Charles and Francis Richmond richmond at plano dot net |
+----------------------------------------------------------------+

[Brian Ketterling]

Post by Charles Richmond
Radio Shack sold this same mechanism in a pen plotter of theirs.
I know that RS had a maintenance manual for their plotter, and you
may still be able to order it through them.

For what it's worth, I believe Alps sold this printer-plotter mechanism to a
number of home computer manufacturers around 1985. The Tandy plotter was a
CGP-115, and there were also the Atari 1020 and Texas Instruments HX-1000,
among others.

Amazingly, Radio Shack has a diagram of the mechanism ("head assembly")
here:

http://support.radioshack.com/support_accessories/5632.htm

Brian
--

[Fergus Logan]

Thanks for the info.

Post by Brian Ketterling

Post by Charles Richmond
Radio Shack sold this same mechanism in a pen plotter of theirs.
I know that RS had a maintenance manual for their plotter, and you
may still be able to order it through them.

For what it's worth, I believe Alps sold this printer-plotter mechanism to a
number of home computer manufacturers around 1985. The Tandy plotter was a
CGP-115, and there were also the Atari 1020 and Texas Instruments HX-1000,
among others.
Amazingly, Radio Shack has a diagram of the mechanism ("head assembly")
http://support.radioshack.com/support_accessories/5632.htm
Brian
--

[a***@netzero.com]

Post by Fergus Logan
Is there such a thing as a service manual for the 1520 printer plotter, or
the Alps plotter mechanism?
I have 2 of these beasts, both with the same problem; the paper feed slips.
On the right hand side of the mechanism, the cog that is attached to the
platten seems to have a spring that has come loose. This cog has two wheels
to it and appears to be some sort of clutch mechanism. does anyone know how
the cog should look with the spring in the correct place?
Kind Regards,
Fergus.

IIRC, the main failure mode of these printers is that the plastic gear
on the motor's shaft cracks. You can't repair that failure. I'm not
sure what you mean by "slips", but if the gear is cracked, the printer
can't feed paper properly.

[Brian Ketterling]

Post by a***@netzero.com
IIRC, the main failure mode of these printers is that the plastic gear
on the motor's shaft cracks. You can't repair that failure. I'm not
sure what you mean by "slips", but if the gear is cracked, the printer
can't feed paper properly.

Arr... the pinion gear on the X and Y stepper-motor shafts? One of those
split on my plotter, and I was never able to find a replacement: Alps seems
to have used a gear with some arcane combination of diameter and pitch. I
was able to fix it to the "workable" point, though, with Sicomet #50
adhesive. It both filled the crack and glued the gear to the shaft,
preventing slipping -- I just precleaned carefully with acetone, then
cleared the set adhesive from between adjacent gear teeth with an X-Acto.
It's probably been a decade, and the fix is still good (as far as I know --
I haven't dug out the plotter this summer). Of course, when the pinion gear
split (longitudinally, between 2 teeth), the sides of the crack retracted a
little from each other, so I've got that damn little "long step" on the Y
axis. It's a niggling concern, though -- for example, text at small sizes
is still perfectly legible.

Brian
--

[Raymond Day]

Yes the thing that goes bacd on the 1520 plotter is the plastic gears! It's
like they get old and brittle. There are 2 of them to gether with a spring.
I guess so the teeth in the gears can be real tight. But printing out
something that takes a lot to do like a screen dump can crack the gears.

To bad they did not make the gears out of metal or steel. Or a 80 column
one.

I remember at one time long ago toys R us selling them for very cheep. I for
get what cost just that it was very cheep. It would be good to have a back
up. But I think with out ever using on with the age the plastic gears would
still crack.

-Raymond Day

[Fergus Logan]

After closely checking these gears I did notice that on one of the
mechanisms this is indeed the case, and you physically see the motor
spinning, but the gear does not turn. However, on the other mechanism, this
gear does seem intact and all gears on the feed mechanism spin as they
should. However, the feed still slips. I am not sure whether or not the gear
with the spring mechanism has anything to do with it, but it certainly isnt
attached to anything at the moment.

Post by Raymond Day
Yes the thing that goes bacd on the 1520 plotter is the plastic gears!
It's like they get old and brittle. There are 2 of them to gether with a
spring. I guess so the teeth in the gears can be real tight. But printing
out something that takes a lot to do like a screen dump can crack the
gears.
To bad they did not make the gears out of metal or steel. Or a 80 column
one.
I remember at one time long ago toys R us selling them for very cheep. I
for get what cost just that it was very cheep. It would be good to have a
back up. But I think with out ever using on with the age the plastic gears
would still crack.
-Raymond Day

[a***@netzero.com]

Post by Fergus Logan
After closely checking these gears I did notice that on one of the
mechanisms this is indeed the case, and you physically see the motor
spinning, but the gear does not turn. However, on the other mechanism, this
gear does seem intact and all gears on the feed mechanism spin as they
should. However, the feed still slips. I am not sure whether or not the gear
with the spring mechanism has anything to do with it, but it certainly isnt
attached to anything at the moment.

There you go. Sadly, this is why the 1520 is a door-stop or a
paper-weight. You can improvise new pens, or drill them out and try to
fill them, but those gears are hopeless. I think they crack because
they are just poorly designed. There just isn't enough plastic (nylon?)
left around the shaft and the friction-fit stresses the gear too much.

I've wanted to make a mold of it and somehow make a new one but when
you can get inkjets for 60$, who cares anymore?

[silverdr]

Post by a***@netzero.com
I've wanted to make a mold of it and somehow make a new one but when
you can get inkjets for 60$, who cares anymore?

Well, some people do. Isn't it the same as "when you can get a pc for
$100 or less, who cares about the PETs" ;-)

[a***@netzero.com]

Post by silverdr

Post by a***@netzero.com
I've wanted to make a mold of it and somehow make a new one but when
you can get inkjets for 60$, who cares anymore?

Well, some people do. Isn't it the same as "when you can get a pc for
$100 or less, who cares about the PETs" ;-)

Not really, people never built new gears for old printers, but you can
still program old computers today and build generic electronics for
them... Making nylon gears is a bit less accessible I think. :)

[Charles Richmond]

Post by a***@netzero.com

Post by silverdr

Post by a***@netzero.com
I've wanted to make a mold of it and somehow make a new one but when
you can get inkjets for 60$, who cares anymore?

Well, some people do. Isn't it the same as "when you can get a pc for
$100 or less, who cares about the PETs" ;-)

Not really, people never built new gears for old printers, but you can
still program old computers today and build generic electronics for
them... Making nylon gears is a bit less accessible I think. :)

Maybe a group here can get together and get a machine shop to tool
up some steel gears. Or who ever does this work...perhaps someone
can "forge" some nylon gears.

You can find a list of folks who make nylon gears at:

http://www.thomasnet.com/products/nylon-gears-34200402-1.html


--
+----------------------------------------------------------------+
| Charles and Francis Richmond richmond at plano dot net |
+----------------------------------------------------------------+

[Brian Ketterling]

Post by Charles Richmond
Maybe a group here can get together and get a machine shop to tool
up some steel gears...

Or brass.

Brian
--

[a***@netzero.com]

Post by Charles Richmond
http://www.thomasnet.com/products/nylon-gears-34200402-1.html

If we could find a machinist or mech eng that specializes in these tiny
gears it would be cool. Or perhaps we can think sideways and look into
toys like those miniature r/c cars that you can buy parts for... The
best thing would be to measure the 1520's gear with a good caliper and
get all the relevant data on it. # of teeth, pitch, etc...

My 1520 is in deep, deep DEEP storage. As in I don't know where it is.

[Ferg]

Your absolutley right about the price of a new Inkjet. Here in the UK,
you can pick them up for less then the price of an ink cartridge these
days. But the 1520 has the novelty factor that you just dont get with
printers these days.

Mind you, the printer doesnt really help itself; when you power the
thing up, the pen carriage shoots to the left and makes a grinding
noise, before finally printing the four squares. I wonder if the other
manufacturers plotters did this same ritual, or is it just a Commodore
thing.

Post by a***@netzero.com

Post by Fergus Logan
After closely checking these gears I did notice that on one of the
mechanisms this is indeed the case, and you physically see the motor
spinning, but the gear does not turn. However, on the other mechanism, this
gear does seem intact and all gears on the feed mechanism spin as they
should. However, the feed still slips. I am not sure whether or not the gear
with the spring mechanism has anything to do with it, but it certainly isnt
attached to anything at the moment.

There you go. Sadly, this is why the 1520 is a door-stop or a
paper-weight. You can improvise new pens, or drill them out and try to
fill them, but those gears are hopeless. I think they crack because
they are just poorly designed. There just isn't enough plastic (nylon?)
left around the shaft and the friction-fit stresses the gear too much.
I've wanted to make a mold of it and somehow make a new one but when
you can get inkjets for 60$, who cares anymore?

[a***@netzero.com]

Post by Ferg
Your absolutley right about the price of a new Inkjet. Here in the UK,
you can pick them up for less then the price of an ink cartridge these
days. But the 1520 has the novelty factor that you just dont get with
printers these days.
Mind you, the printer doesnt really help itself; when you power the
thing up, the pen carriage shoots to the left and makes a grinding
noise, before finally printing the four squares. I wonder if the other
manufacturers plotters did this same ritual, or is it just a Commodore
thing.

Perhaps a microswitch is defective? Don't know if there is one, but
tiny cheap switches with no current going through them to "clean" the
contacts often go bad.

[Ferg]

No. It is the normal behaviour on the 1520. I have seen this on others,
and back in the '80s when mine was new, it did that then too.

Post by a***@netzero.com

Post by Ferg
Your absolutley right about the price of a new Inkjet. Here in the UK,
you can pick them up for less then the price of an ink cartridge these
days. But the 1520 has the novelty factor that you just dont get with
printers these days.
Mind you, the printer doesnt really help itself; when you power the
thing up, the pen carriage shoots to the left and makes a grinding
noise, before finally printing the four squares. I wonder if the other
manufacturers plotters did this same ritual, or is it just a Commodore
thing.

Perhaps a microswitch is defective? Don't know if there is one, but
tiny cheap switches with no current going through them to "clean" the
contacts often go bad.

[Brian Ketterling]

Post by Ferg
No. It is the normal behaviour on the 1520. I have seen this on others,
and back in the '80s when mine was new, it did that then too.

It's getting itself oriented during its power-up initialization. First it
drives the "head" to the left stop. It doesn't have a switch or other
sensor for this, so it simply does enough motor-steps to place it there,
even if it had been at the full-right position at power-on. If it *wasn't*
full-right to start with, then it hits the left stop and "grinds" its way
through the full number of steps -- kind of like a 1541 head-bump.

After this, it orients the rotating four-color pen turret to the "black"
position. It does have a sensor for this: there's a little bar magnet set
into the side of the turret which activates a magnetic reed switch on the
carriage's frame. You can hear this second stage, too -- a
"ticka-ticka-ticka, ticka-ticka-ticka" as it steps the turret around.

Finally it draws the four-color squares to get the pens started, feeds to a
new line, then comes to rest.

You can avoid the nasty grinding by pressing the pen-change button and
letting it ride over to the full-right position before turning it off (you
ought to anyway, so you can take the pens out and cap them -- they use
liquid ink and will dry up if you leave them in the plotter).

Brian
--

[Ferg]

Your absolutley right about the price of a new Inkjet. Here in the UK,
you can pick them up for less then the price of an ink cartridge these
days. But the 1520 has the novelty factor that you just dont get with
printers these days.

Mind you, the printer doesnt really help itself; when you power the
thing up, the pen carriage shoots to the left and makes a grinding
noise, before finally printing the four squares. I wonder if the other
manufacturers plotters did this same ritual, or is it just a Commodore
thing.

Post by a***@netzero.com

Post by Fergus Logan
After closely checking these gears I did notice that on one of the
mechanisms this is indeed the case, and you physically see the motor
spinning, but the gear does not turn. However, on the other mechanism, this
gear does seem intact and all gears on the feed mechanism spin as they
should. However, the feed still slips. I am not sure whether or not the gear
with the spring mechanism has anything to do with it, but it certainly isnt
attached to anything at the moment.

There you go. Sadly, this is why the 1520 is a door-stop or a
paper-weight. You can improvise new pens, or drill them out and try to
fill them, but those gears are hopeless. I think they crack because
they are just poorly designed. There just isn't enough plastic (nylon?)
left around the shaft and the friction-fit stresses the gear too much.
I've wanted to make a mold of it and somehow make a new one but when
you can get inkjets for 60$, who cares anymore?

[Aturnwald]

Hello, I've got the Manual, also I've got help for the paper problem, just write a Email to ***@eclipso.at

[IDLookout]

I can't get your email to work, not sure if you're still in the group, but:

My gears are new, everything is fine.. mostly.

But my paper slips, with just a little pressure, i can hold the gear and turn the platen. There are no splits in the gears. It does seem like there is a clutch/spring in the platen roll, but i'm not sure.

You said that you had a solution?

thanks for your time

[Aturnwald]

Hello, I've got the Manual, also I've got help for the paper problem, just write a Email to ***@eclipso.at