>I didn't work in the video industry, John, but I did work with computers all
>the while. Monitors of the time, at least of the NTSC-compatible type, were
>typically equipped with PL-259 connectors on the rear. The only video
>monitors I encountered with BNC connectors on them were the high-frequency,
>then-mono, types, from Motorola, intended for use as "page" monitors.
I think it might have had more to do with what kind of single was being
sent. (at least in the video industry)
My old UMatic decks from the 70s have either "UHF" connectors (PL-259),
or F connectors (depending on age) for all the modulated signals
(connects to a TV shows on either channel 3/4 or 6), but all the ones
that have composite signals (non-modulated, needs a "line in") have
either BNC or RCA (depending on quality, doesn't seem to have bearing on
age... higher quality decks have the BNC for video, RCA for audio, and
lower quality have the RCA for video and audio).
I don't think I have ever seen a "UHF" (PL-259) or F connector on a non
modulated composite signal (not saying they don't exist, just I have
never seen them), same with I don't think I have ever seen a BNC or RCA
on a modulated signal.
-chris
<http://www.mythtech.net>
At 02:12 PM 1/24/02 -0500, you wrote:
>On Thu, 24 Jan 2002, Fred Cisin (XenoSoft) wrote:
>
> > Zip drives use one that is 5 VDC. Do they really need 5?
>
>IIRC, the Zip-Drive 'wall wart' is actually a complete regulated power
>supply. So to operate the logic, it DOES need to be 5VDC.
All of this is off-topic, but I've got three different types of Iomega
ZIP drive "wall warts" here (all voltages unloaded, measured from
my Fluke 8020A):
57DR-5-1500(A) outputs 5.21 volts DC
48DR-5-1000 outputs 5.11 VDC
91-56403 outputs 5.15 VDC
Much closer to spec than most wall warts.
Cheers,
Dan
In a message dated 24/01/02, pete(a)dunnington.u-net.com writes:
> Whether you need to unsolder all the keyswitches depends on the keyboard --
> there were 4 types, but only one -- fortunately the least common type --
> needs much work. The best, and original, was the type using Futaba
> keyswitches, which have a white body. These are easy to remove, one at a
> time (desolder the connections, then release the clips which hold the
> keyswitch in the frame). I've seen a couple of pictures on the web showing
> the different types but I can't seem to find one right now :-(
>
> The normal way to fix faulty ones was to replace them. You can still
> sometimes find switches available from people who've dismantled machines.
> If not, I'd try removing the faulty keyswitches and cleaning them by
> swishing them in a small bowl of iso-propyl alcohol, or squirting IPA
> followed by switch cleaner through them. Finish with a good-quality
> low-residue switch cleaner. These are generally based on IPA with small
> amounts of very light oil (not usually silicone, as it creeps too much and
> gets into everything). Do not use anything like WD40!
>Pete Peter Turnbull
> Network Manager
> University of York
Great, thanks for the advice Pete. Did a quick search with Goolge and found
a few tips on BBC keyboard repair. It seems I have a type I keyboard with
Futaba keyswitches fitted. They come out of the frame one at a time.
After a bit of fiddling I discovered that the keyswitch body is held together
by a small plastic clip and two screws. The terminal pins are the screws
and can be removed by gently rotating with a pair of pliers.
Terminal pins are silver plated and show signs of tarnishing on the faulty
keyswitches. The contact leaf springs appear to be OK. A mild abrasive
and some IPA should do the trick :-)
Just wish I'd kept that Cherry keyboard form years ago with the Hall effect
switches.
Chris
Hello, all:
I am finally getting around to building the P112 Z180-based SBC from
Dave Brooks (I got one of his last unpopulated boards). It has two 100-pin
QFP chips (the Z180 and an SMC Super I/O chip), so, I bought the blade-like
SMD soldering iron tip for my iron.
So, here's the stupid question...how do I solder these things? Do I
hold the iron parallel or perpendicular to the package leads? The board is
pre-tinned, but I should I also tin the QFP leads?
Any help appreciated.
Rich
>From: ard(a)p850ug1.demon.co.uk (Tony Duell)
>Do these tap into the plastic of the case, or into brass inserts, or what?
They go into pre-drilled cylindrical studs that extend from the back of the
case (the side that doesn't plug into the wall) toward the front. There
were matching
cylindrical recess barrels from the front that extended toward the back and
had holes in their circular bottoms large enough for the screw threads to
pass through. Those barrels were what melted.
>Are they machine screws, self-stripping screws (OK, self-tapping screws
>:-))? If they're machine screws, they're likely to be metric sizes....
Self-stripping :-) which is what I'll therefore replace them with.
>Ignoring the ceramics (likely to be for RFI suppression), it would appear
>you're describing this circuit :
>
>
>o-----)|| +---------------+------------o +ve output
> )||(------>|----+ |
> )||( | =====
> )||(--o\o-------)----+ -----
> )||( | | |
> )||(------>|----+ +----------+-------------o -ve output
>o-----)||
>
>A very standard PSU circuit using a 'bi-phase' full wave rectifier.
I think that's it. Why did I see a small voltage when I tested it *after*
the fuse blew? The - side doesn't connect to *anything* - I'd think it'd
float right up to the voltage of the positive side (charging through my VOM
meter, if no other way). Or is there some effective resistance through the
electrolytic?
>Is there room to insert a normal fuseholder (maybe a 20mm one), then you
>could use a fuse without pigtails...
Hm. Maybe. I actually have a small fuseholder (one of the few parts I have
in my box). I'll see whether I can make it fit. It would mount in among
caps and diodes with not much room to spare on a small circuit board,
though, so I may be stuck with a pigtail version.
- Mark
> -----Original Message-----
> From: ard(a)p850ug1.demon.co.uk [mailto:ard@p850ug1.demon.co.uk]
> You do realise that BNC connectors were used for RF and video
Well, it stands to reason, I suppose.
> applications long before there was any form of ethernet, I
> take it. The
> video ones are likely to be '75 Ohm' characterisic impedance,
> so you'd
> have to get the right plugs to fit them. 50 Ohm plugs will
> fit, but the
> larger centre pin will spread out the contacts on the socket.
> And anyway
> you'll have an impedance mismatch. I doubt you'd notice the slight
> ringing from that on the screen, but it never hurts to do
> things right.
I have a 50-75 ohm converter, I believe. I'll need to dig it up.
> it's separate outputs for the standard (40 column) video from the
> motherboard and for video from an 80 column expansion card.
Hadn't thought of that.
Chris
Christopher Smith, Perl Developer
Amdocs - Champaign, IL
/usr/bin/perl -e '
print((~"\x95\xc4\xe3"^"Just Another Perl Hacker.")."\x08!\n");
'
> -----Original Message-----
> From: Fred Cisin (XenoSoft) [mailto:cisin@xenosoft.com]
> There're a lot of different connectors that get used for composite
> monitors. For school use, they want one that can withstand
> some abuse,
> and will stay on. (When somebody trips over the cord, it
> should be strong
> enough to pull the entire machine off of the table.)
Heh. That was my first guess too -- but I've never seen this particular thing used on a composite video signal before. (Well, maybe the L+sync used on b&w monitors...)
My assumption will be (until I can check it out) that these are simply split off of the original apple RCA plug on the mainboard, and carry the same signal. (I hope this is the case, since it would be a simple matter of fabricating an adaptor (for which I may have the parts...).
> an unusual connector, with a hollow cylindrical plug a few
> inches long,
> with a pin in the center. I had to check out a cable each
Got pictures of this thing?
> time to use it,
> until Electronics Etc (R.I.P.) came up with an adapter of that plug to
> BNC.
> OB_CC: My TRS-80 model 1 was quite happy sending signal to
> half a dozen
> giant overhead monitors.
I don't see why it wouldn't be.
Regards,
Chris
Christopher Smith, Perl Developer
Amdocs - Champaign, IL
/usr/bin/perl -e '
print((~"\x95\xc4\xe3"^"Just Another Perl Hacker.")."\x08!\n");
'
Does anybody out there have the docs available for the TSU05 controller
board used in PDP-11s or VAXes with UNIBUS to connect to the DEC variant
of the Cipher F880?
The board is M7455, and I am looking for the meanings of the DIP
switches.
There must be CSR address and interrupt vector, each made up by several
individual switches, but in addition to that, an "extended features"
switch and one for "buffering".
And, no, I am certain that I did not confuse this with the TSV05 (M7196)
for Qbus.
Thanks in advance!
Andreas
--
Andreas Freiherr
Vishay Semiconductor GmbH, Heilbronn, Germany
http://www.vishay.com
On January 24, Andreas Freiherr wrote:
[pdp11/34]
> Try this: enter 773000, load this address, and then press START. Since
> 773000 is the standard start address for a bootstrap ROM, this should
> get you a response on the console terminal attached to the DL-11W.
> (Don't remember which, but I think it should ask for a two-letter device
> code to boot.)
It'll print the contents of R0, R4, R6, and R7, then give you a "@"
prompt on the next line, at which you'd type a two letter device name
to boot from.
-Dave
--
Dave McGuire
St. Petersburg, FL "Less talk. More synthohol." --Lt. Worf
