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HP7004B X-Y plotter schematic

 

Hi, would anyone have a schematic for the HP7004B plotter, I went to use it the other day to do some plots from my 141T and it no longer wants to play the game. I checked all the electrolytic capacitors (considering its age) and replaced some to no avail, all I managed to do was introduce another fault, pen solenoid no longer works. Original fault was X very unstable. All that I can find by searching the internet was a user/operator manual.
Thanks Steve.
 

If fit is like the plotters I used in college, there are wires that the carriage slides along to sense its position - clean them carefully. The symptom is "vibrating" or spastic motion of the x r y carriage. The other possible problem if it is vibrating could be the damping adjustments.
Cheers!

Bruce
oting Steve Dench <sjdench48@...>:

Hi, would anyone have a schematic for the HP7004B plotter, I went to use it the other day to do some plots from my 141T and it no longer wants to play the game. I checked all the electrolytic capacitors (considering its age) and replaced some to no avail, all I managed to do was introduce another fault, pen solenoid no longer works. Original fault was X very unstable. All that I can find by searching the internet was a user/operator manual.
Thanks Steve.
 

Thanks Bruce, I will do that with those slide wire resistors. On the main pcb there are two brown blocks, one of these is badly burnt, if they are power resistors as I suspect it is probably still ok, this is another reason I was looking for the schematic.?
Cheers Steve

On Sat, 17 Oct 2020, 12:50 pm Bruce, <bruce@...> wrote:

If fit is like the plotters I used in college, there are wires that?
the carriage slides along to sense its position - clean them?
carefully. The symptom is "vibrating" or spastic motion of the x r y?
carriage.? The other possible problem if it is vibrating could be the?
damping adjustments.
Cheers!

Bruce
? oting Steve Dench <sjdench48@...>:

> Hi, would anyone have a schematic for the HP7004B plotter, I went to?
> use it the other day to do some plots from my 141T and it no longer?
> wants to play the game. I checked all the electrolytic capacitors?
> (considering its age) and replaced some to no avail, all I managed?
> to do was introduce another fault, pen solenoid no longer works.?
> Original fault was X very unstable. All that I can find by searching?
> the internet was a user/operator manual.
> Thanks Steve.
>
>
>








 

厂迟别惫别………..

?

As pointed out the unstable X or Y axis (jitter) is caused by poor contact to the long liner resistors along the X and Y axis. The resistors and the sliding contact brush would have to be cleaned.

At the time we would use alcohol and so forth to clean both areas. The resistors would sometimes be gently and carefully cleaned with a soft rubber eraser.

As for schematics, I am retired from the industry, but this is old equipment and would think that information should be around.

Good luck
 

I wonder if Caig Faderlub would be good for this.

On 10/17/2020 9:38 AM, John Annison wrote:

厂迟别惫别………..

As pointed out the unstable X or Y axis (jitter) is caused by poor contact to the long liner resistors along the X and Y axis. The resistors and the sliding contact brush would have to be cleaned.

At the time we would use alcohol and so forth to clean both areas. The resistors would sometimes be gently and carefully cleaned with a soft rubber eraser.

As for schematics, I am retired from the industry, but this is old equipment and would think that information should be around.

Good luck
--
Richard Knoppow
dickburk@...
WB6KBL
 

I was about to say the same thing. DeOxit, would also be good, this being a metal element.

-Dave

On 10/17/20 2:00 PM, Richard Knoppow wrote:
?? I wonder if Caig Faderlub would be good for this.
On 10/17/2020 9:38 AM, John Annison wrote:

厂迟别惫别………..

As pointed out the unstable X or Y axis (jitter) is caused by poor contact to the long liner resistors along the X and Y axis. The resistors and the sliding contact brush would have to be cleaned.

At the time we would use alcohol and so forth to clean both areas. The resistors would sometimes be gently and carefully cleaned with a soft rubber eraser.

As for schematics, I am retired from the industry, but this is old equipment and would think that information should be around.

Good luck
--
Dave McGuire, AK4HZ
New Kensington, PA
 

HP used to include a little vial of silicone oil for
lubricating the slide wire on X-Y plotters. It is a
nasty stuff that creeps everywhere.

I think I would take Richard's idea and just use Faderlube.
It is very good at eliminating noise on pots... which is
much the same problem here.

-Chuck Harris

Dave McGuire wrote:


? I was about to say the same thing.? DeOxit, would also be good, this being a metal
element.

????????????? -Dave

On 10/17/20 2:00 PM, Richard Knoppow wrote:
??? I wonder if Caig Faderlub would be good for this.

On 10/17/2020 9:38 AM, John Annison wrote:

厂迟别惫别………..
 

What is a 7004B, is it a bed plotter?? I think back in those days you actually could get a real service manual, non of those CLIPS.? If I can get up to my attic I'll check my stack of manuals.? Jim
 

Slide wire (an oil lube that HP supplied)
Zero pots
Variable gain pots

External bad connections (picks up 60 Hz)

The platten (static hold down) can get picky.

Then comes the spring thing that holds the pens.

On Saturday, October 17, 2020, 4:35:51 PM EDT, J via groups.io <emptech@...> wrote:


What is a 7004B, is it a bed plotter?? I think back in those days you actually could get a real service manual, non of those CLIPS.? If I can get up to my attic I'll check my stack of manuals.? Jim

 

Thank you all for your suggestions,? I cleaned the slide wires with Cramolin Red, same as deoxit, but it made no difference. I do believe the fault to be electrical considering its age most likely? a capacitor or resistor gone high. To this end I have removed the main circuit board to give better access (quite a task since they didnt use multi pin connectors for the board connections but each wire is a separate push on connector).
Without a schematic its guess work but hopefully it will work out.
Cheers Steve.

On Sun, 18 Oct 2020, 8:29 am KeepIt SimpleStupid via , <keepitsimplestupid=[email protected]> wrote:

Slide wire (an oil lube that HP supplied)
Zero pots
Variable gain pots

External bad connections (picks up 60 Hz)

The platten (static hold down) can get picky.

Then comes the spring thing that holds the pens.

On Saturday, October 17, 2020, 4:35:51 PM EDT, J via <emptech=[email protected]> wrote:


What is a 7004B, is it a bed plotter?? I think back in those days you actually could get a real service manual, non of those CLIPS.? If I can get up to my attic I'll check my stack of manuals.? Jim

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