a bit off topic.. about diodes

Hi,

I have a dead plotter laying around..
two diodes are blown away.

They are signed: MR 501 1807

from what I can see in the repair manual
those are motoroloa rectifier diodes 100V 3A
I think this should be the matching datasheet:
[www.datasheetarchive.com]

I don't know what the second number is for so I take it as a charge number

Since they are out of production for a while now, is it safe to presume that I can replace them with 1N5401
datasheet: [www.datasheetcatalog.org]

or am I missing something ?

thanks
'sid

PS sorry for asking non reprap related questions

Any idea how the old ones ended up blown away?

5401 should work here, unless you have > 100V or >3A current. Just be sure to place the cathode right.

That's exactly how the old ones where blown
I got the plotter seventh(?) hand.. someone tried to repair it and messed things up.
Not only the rectifier but there are also cables missing, shorted fuseholders and further more, I'm not quite done with errordetection

Let's say: there are some parts to replace

but the worst thing that I just figured is:
I need to have some sort of controller which seems to be pretty expensive
it has an HPIB bus; any controller I could find so far is way over 200 Euros (up to fivehundred).

*grmpf*
Or I'll just rip the electronics and make my own.
Unsure right now.

But thanks for confirmation on the 1N5401

'sid

> but the worst thing that I just figured is:
> I need to have some sort of controller which seems
> to be pretty expensive
> it has an HPIB bus; any controller I could find so
> far is way over 200 Euros (up to fivehundred).

Sounds like really old hardware to me. Maybe try to control every part you need and hook it up onto an arduino.

extremely old (in computer years, close to stone age) (d.o.b. sep. 12th 1981 !)
Any questions?

Yes, something like that was what came up to my mind too
just use the reprap controllers with modified firmware to be precise.

But, no more missing or errorous parts I could find right now.
So first I'll try to replace the diodes, add a new cable and fuseholder
and see if I can run it in "testmode" to see what else is to be replaced.

And if it's working I may search closely for a cheap controller,
I'd love to keep the controlpanel functional (I doubt I would succeed with homebrew stuff) we'll see... we'll see

'sid

PS for those who are curious enough a HP 9872C

Hi sid,

i have an ISA-card GPIB-interface and a second 'naked' PCB somewhere in my stock - i think it's the same as HPIB, but i didn't have running software or a working PC with ISA-slots at hand.

This should be an assembled kit out from a book of 1985 or so, maybe with a floppy and some software on it, but i have to search to find the book and the parts.

Tell me if it's worth a try ...

Viktor

thanks Viktor,
honestly, but I don't have any working PC with an ISA slot either.
So that wouldn't help me out I'm afraid.
Yes I think GPIB is "the same" well at least compatible.
There is an australian company, that sells usb interfaces for relatively cheap:
[www.ar.com.au]

That is, after a successful testrun

'sid

Should be pretty easy to ebay an isa motherboard. They were used as late as PII.

Otherwise, have a look for ISA slotcard computers and PC/104 computers. Both of those still use ISA.

[www.tri-m.com] has loads of this stuff. It's used for embedded systems, so some of it is quite expensive, but there are PC/104 computers that can be had for about $100.

I know I know, I'm sure I do have one of those PII (I think even a PIII Slot1 Mainboard) with an ISA Bus laying around somewhere, but to be honest, I don't want to just build another PC just for controlling a plotter that may never work*

*I fixed obvious errors today, now there's still at least one other that I didn't found yet.
(power on, *buzzrrrr*, fuse toast anyone?)

But what I've found for controlling purpose is
a) on the connectorboard there's a place for a serial connector *grin*

b) but only If I cannot run that beast with just a custombuild cable that is*

*found instructions for cable and software on the net..
and that is cheap I must say: 1.20 for some parallel cable 1.50 for a centronics 24pin male plug and free software...
cheap and non invasive

'sid

Well....

I think I need your help again, sorry.

I found a 0 Ohm capacitor that may have caused all the errors I was encountering,
but since all I have here to test is a simple multimeter there are some doubts I have.

1) can I trigger the gate of a 2n6505 datasheet:[www.onsemi.com] scr with my multimeters continuity test?
that is: should cathode vs gate beep?

2) those two pins (cathode // gate) are connected via an 51.5 Ohm resistor;
what resultant resistance should I measure ? (short: is 33.x Ohm okay? )
it's R1*R2/(R1+R2) = Rres ; isn't it?

3) and I promise this is my last one (although a bit bulky )
I had some capacitors in sight causing troubles, the first one I tried to desolder broke (stupid me wasn't very gentle) But I cannot find replacement.

it's marked 1.0M X5V 25V with a big E on the back.. the datasheets says
manufacturer: Hewlett packard (oh perfect ) order number 0160-0127
description: 1uF +-20% 25VDC CER
any ideas where to find a replacement.

And now the bulky part
3a) *gg* other caps I'd like to replace but can't find matching
is an 390uF 20V AL (dxl: 13x33 mm)
and the dead one : 330uF 50V AL (dxl: 22x30 mm)

3b) can I replace them with the next bigger values even in capacity?
(eg instead of 390uF 20V just take an 470uF 40V ?)

So, I guess that's it... at least for now

Thanks a million

'sid

Edited 1 time(s). Last edit at 12/04/2008 12:55PM by sid.

Hi sid,

with 1. and 2. you're measuring a network of diodes and resistors - this could tell you strange values and some multimeters have high enough measuring currents, to activate gates ...

For 3. - when you can't find another 1

Edited 1 time(s). Last edit at 12/04/2008 03:01PM by Viktor.

Hi Viktor

1) So I'm fine, you think?
I can't measure the current of the multimeter, I only have that one left,
the other one broke... and you see the dilemma in here

2) I know about the network, but I did't know if I'm right with calculating for parallel resistors assuming the cathode/gate of the 2n6505 to be around 100 Ohm
and the resistor to be around 51.4 Ohms the equation above would result in 33.95 Ohm (I'm measuring 33.6 so I'm fine) But I wasn't sure about the equation at all;
Now some hours and one look at wikipedia later I am

3) combining smaller ones is impossible.
Since they are for filtering I'll go with the closest I can find in Voltage.
I guess I'll find correct values for capacity somewhere.

thanks Viktor

'sid

Hi sid,

... the only important value is the capacity.

The voltage is only a max-isolation-type-value - you can use any higher voltage you find - it should be only some volts higher than your max. applied voltage in the circuit or you'll be possible to receive shortcuts through the capacitor ...

Viktor

sid Wrote:
-------------------------------------------------------
>
> *found instructions for cable and software on the
> net..
> and that is cheap I must say: 1.20 for some
> parallel cable 1.50 for a centronics 24pin male
> plug and free software...
> cheap and non invasive
>
> 'sid

Hi Sid,

Any chance you could post a link to these instructions? It just so happens I recently acquired an HP 9872C as well . It appears to be fully working, but commercial GPIB interfaces are silly money.

Did you find the manuals here: [www.hpmuseum.net]

Thanks,
Nick

Hi Nick;
sure...

be warned, it's a german page so you may need translations for the instructions;

what you need is the plot488.zip for commandline printing of plotfiles
OR
plot488plus.zip if you intend to plot directly from the editor.

[chrbest.home.t-link.de]
you might need to click "Plotterkabel"

instructions for the cable packed in the zip archives

'sid

Oh one thing Nick....

could you do me a favour perhaps?!
Since I'm missing the controlpanel cable in my plotter.

would you mind making a picture of yours connected ?

(two screws on the back, and two from above you just released (captive, do not remove))
See in the linked service manual Feb 81
yes I downloaded all of those to find what I was looking for.

but I can't find the cable informations yet..
is it 1-1 & 50-50 or is it 1-50 & 50-1 or even worse than that?

Thanks a lot, otherwise I'd have to search in the manuals again, which is pretty painful with just the pictures

btw: I just soldered my cable; went pretty okay (for those tiny little wires)
but be careful to have the perfect centronics plug, mine sits that tight, that I cannot remove it without a screwdriver and patients.
might need some filing perhaps

You might even want to take a look at the serial connector which seems to be an optional feature for the connectors pcb (although I am unsure if it's because of other firmware versions or something)

'sid

Oh one more thing... if you open your plotter; please take some pictures, could be helpful since the photos of the manual are pretty dark and useless.

Hi Sid,

Yes, it's 1-1 and 50-50.

I'll take some photos and post links here...

Nick

Ok, try these - they are *slightly* higher resolution than in the manual. Hope you're not on dial-up

photos.nickfines.co.uk/misc/HP9872C_Base.JPG
photos.nickfines.co.uk/misc/HP9872C_Top.JPG
photos.nickfines.co.uk/misc/HP9872C_PCB.JPG

Nick

thanks alot Nick.
and nope, broadband; everything else just doesn't make sense

Now I can at least make the controlboard cable until I can solder the new caps,
not much to do this weekend unfortunately,
neither plotter nor reprap parts not even any watchparts I would need to carry on...
well at least I have some 50ribbon cable and connectors

let me know if you need any help with the plot488 instructions or something.

'sid

The less important yet fascinating status update ...

Got the caps today and yeah it woooorks (at least the psu that is)
the damn controlpanel is NOT.
Maybe due to my homemade cable, maybe due to age.. I'll know within the next 24h

wish me luck

everything else would have been too easy I guess...

'sid

[edit]
well connecting just 25 of 50 pins isn't enough for having a fully working controlpanel
pluged the cable in correctly and now I have a working controlpanel
So.. unfortunately the electrostatic platen isn't working (non permanent solution: tape! )
confidence test: succeed.
inbuild electrnics test: succeed.

plot488 to plot a file: failed!
sid: dissapointed

'sid

[edit v.II]
Well, trying to plot hpgl-2 instructions on a hpgl-1 plotter simply doesn't work but will result in an error
Now, after manually editing the plotfile it plots..
hooray!

Now I need to buy some pens, and learn how to teach coreldraw to export pure hpgl1

'sid

Edited 2 time(s). Last edit at 12/16/2008 09:37AM by sid.