4 Sep
2011
4 Sep
'11
7:30 a.m.
On 03/09/11 19:37, Tony Duell wrote:
It's HP-IB. Unfortunately one of the thumbscrews is missing from the
GPIB connector.
Do you mean the screw-down jackposts on the chassis-mounted connector?
Those are in therory still avaialbe form Agilent (they were used on many
instruments), but I've yet to find a way of getting them in the UK, If
you want to make a replaceemnt, the internal female thread is M3.5, the
male thread to go into the PCB bush is 6-32 UNC, and the hexagon is 9/32"
across flats. Take the other measuremtns from the one you have.
Seriously, I've given up trying to buy them in the UK, I just make them
when I need them.
I've
just acquired a HP 7470A in a lot with some other gear, and it
Nice find!. Which version is it? There are 3, HPIB, RS232 and HPIL (the
last being by far the rarest). Alas you can't easily convert one to
another, there's one PCB inside, and it differs between the versions. How are the rollers removed and reinstalled? I
can't see any obvious way
to remove them without damaging the clamp arms.
In my 7470, there appear to be E-circlips on the ends of the clamp arm
pins that hold these rollers. I assume that removing said circlips allows
the rollers to come off. I can take mine apart if you like.
It appears these rollers have as rigid hub with a rubber tyre. I don't
know if the hob is tapered or not.
I think there's an official service manaul for this plotter (I don't know
which interface version(s) it covers) on the Australian HP museum site.
That probably covers taking the mechanical side apart (which is the same
in all versions).
Turning a
tappered rubber roller is possible, but rubber is not easy to
machine. It helps to cool it, but not too far (I am told that solid CO_2
is about the right tempeature).
Who said anything about machining the roller? :)
I just bought a pack of "Sugru" (a type of putty based on silicone)
which may well work for this. The trick is going to be making some form
of rig to make a tapered rubber roller of the correct size...
I'd thought about using something like Devcon 90 for this, but it's darn
expensive, and the problem of making the mould still applies. For
something this size, it's a lot easier to make an external taper than an
internal one...
-tony