I've got a DataFlyer 500 expansion for my Amiga 500 and it's dead as a
post. There's +5 on the connector but no where else that I can find on
the board. Does anyone here happen to have a schematic for it or know
where I can find one?
tnx.
g.
--
Proud owner of F-15C 80-0007
http://www.f15sim.com - The only one of its kind.
http://www.simpits.org/geneb - The Me-109F/X Project
ScarletDME - The red hot Data Management Environment
A Multi-Value database for the masses, not the classes.
http://www.scarletdme.org - Get it _today_!
I have brought my SWTPC 6800 system back to life that I built as a kid
in 1976. It is pretty heavily loaded with RAM cards, floppy controller,
etc. and the 8V power supply rail was never really able to hold its own.
It sits at about 6.5V now... driving many 5V regulators on the various
cards. No where near enough margin going into those.
So, I am contemplating the following,
1) rebuild entire power supply using three switchers, 7.5v unit nudged
up to 8V and two 12V units to supply +/-12 on the backplane. All of
these will fit inside the original cabinet in place of the linear
supply's transformer, giant electrolytic cap, bridge rectifier, etc.
I'd mount these switchers to an aluminum plate that would fit into the
chassis and use existing mounting holes thereby not drilling any new
holes in the chassis. This would be the least "period" solution but
allow all of the original cards to run in the machine with power to spare.
2) add a new transformer to the existing supply just for the 8V rail.
This will also fit but requires moving the existing transformer, cap,
DC distribution board-- all efforts that require drilling new holes in
the chassis. This would be a more authentic solution since I wouldn't be
introducing power supply designs that didn't exist back then. There were
actually published mods along these lines in the day but I am little
hesitant to butcher the chassis to accomplish this.
3) scuttle the legacy RAM cards, most of which are 4K in size built
with 2102's... and one 16K built with 2114... and replace them with a
single homebrew RAM card using one 32Kx8 SRAM drawing almost no power
in comparison to these old cards. Definitely not period and all the
authentic RAM cards would be sitting on the shelf then but the power
supply could remain unmodified.
Any recommendations on the best choice?
Chris
--
Chris Elmquist
Hi,
If anyone wants a Macintosh IIcx motherboard (free, and allegedly "new"),
please email me offline at sieler at allegro.com.
Board was found in the estate of a friend, box is marked as "new".
Board was unopened until I broke the seal so I could get the
model number:
Macintosh IIcx Apple Computer
820-0230-B (c) 1988
Preference goes to anyone who can pick it up in Cupertino, CA.
Otherwise, cost of shipping Fed-Ex is needed.
thanks,
Stan
My 2 pennorth,
The business of listing "4 systems you have had experience of" is a
little odd & seems to hint at an administration that don't know one end
of an electrolytic from the other, it's rather like choosing a builder
based upon "what type of housing stock he's worked on". ("Door
sticking?, No mate, I only do victorian terraces & 1930s semis")
Personally I was musing with the idea of volunteering when the kids are
both in school, as I'm 44 and have been doing electronics for about 42
years, and I'm not a million miles away, but it's going to kill me
seeing stuff rot, and not being able to get my hands dirty for the sake
of a piece of paper.
To Ethan Dicks,
7 years ago, you posted in an electronics forum, asking about how to install a composite video input into a cheap, 5 inch, 12 Volt b/w TV set. I've discovered how to do so, and if you're still interested but haven't found out, Let me know and I'll send you the info. I know this message may seem strange, coming to you so very looong after you first posted the question, but oh well...
Here is the link to the forum where you posted the question.
http://www.classiccmp.org/pipermail/cctalk/2003-March/020120.html
Sincerely,
Justin Newman
NewmansKnight at bellsouth.net
Hi All,
Cool TI Micro terminal on ebay for the 990 family
Item # 300432266833
Rob
Rob Borsuk
email: rborsuk at colourfull.com
Colourfull Creations
Web: http://www.colourfull.com
On 5/31/10 10:54 AM, Rob Jarratt wrote:
> Why is the graphite pad needed? What would happen if I
> removed it?
>
static charge builds up, and zaps the read preamps.
On 31/05/2010 18:54, Rob Jarratt wrote:
> Thanks to the people on this list and one other (thanks Matt!) I have got my
> RD53 working reliably now. I currently have it installed in a MicroVAX 2000
> with 6MB of memory running MicroVMS 4.6 and DECnet.
>
> I had to remove the old bumper which had become sticky. But to make the disk
> work I had to replace the bumper, so I used some folded over post-it notes
> taped to the top of the head assembly. This seems to work for now, but I
> fear a better solution is needed.
You could try a thin bump-on rubber foot, as used on some small
electrical equipment.
> I also get a grinding noise which becomes
> apparent after the disk has warmed up. I think this comes from the graphite
> pad underneath. I plan to loosen the mounting bolts a little more to see if
> that gets rid of the noise, but I am wondering if there is any other way to
> get rid of it. Why is the graphite pad needed? What would happen if I
> removed it?
It's an antistatic measure for the spindle. Try bending it a little.
It's unlikely to do any harm running with it bent right our of the way
for a while, so you can find out if that's what's making the noise.
--
Pete Peter Turnbull
Network Manager
University of York
> apparent after the disk has warmed up. I think this comes from the graphite
> pad underneath. I plan to loosen the mounting bolts a little more to see if
> that gets rid of the noise, but I am wondering if there is any other way to
> get rid of it. Why is the graphite pad needed? What would happen if I
> removed it?
The graphite pad is an earthing contact for the spindle/disks. The idea
is that if the spindle is insulated from the chasis, static build-up
could cause data errors (or even damage to the read amplifier). I've seen
plenty of dissk runnign without the earthing contact, so it is probably
not essential to have it.
Often if you bend the mountign spring so a different bit of the pad
touches the spindle, the noise will go away. Another trick is to stick
something (foam tape is good) on the spring to deaden the sound.
-tony
Thanks to the people on this list and one other (thanks Matt!) I have got my
RD53 working reliably now. I currently have it installed in a MicroVAX 2000
with 6MB of memory running MicroVMS 4.6 and DECnet.
I had to remove the old bumper which had become sticky. But to make the disk
work I had to replace the bumper, so I used some folded over post-it notes
taped to the top of the head assembly. This seems to work for now, but I
fear a better solution is needed. I also get a grinding noise which becomes
apparent after the disk has warmed up. I think this comes from the graphite
pad underneath. I plan to loosen the mounting bolts a little more to see if
that gets rid of the noise, but I am wondering if there is any other way to
get rid of it. Why is the graphite pad needed? What would happen if I
removed it?
Thanks
Rob
