I take a bench power supply and a resistor and bring the caps up that way- sometimes you have to disconnect a wire or two, but not always, and the resistor gives you a degree of safety a straight variac wouldn't.
>
>Subject: Building M8027 hookup
> From: "Wolfe, Julian " <ISC277 at CLCILLINOIS.EDU>
> Date: Tue, 06 Dec 2005 18:06:31 -0600
> To: "'General Discussion: On-Topic and Off-Topic Posts'" <cctalk at classiccmp.org>
>
>OK, I'm trying to build myself a hookup for an M8027(LPV11) to run to my
>distribution panel.
>
>I've done some reading, and it is clear that this is a Centronics compatible
>card, so I have the right one.
>
>Does anyone know the pinout for this device? I'm confused. I know you can
>use other printers with this card, and I'm just looking to do raw text to an
>old Panasonic dot matrix printer - but I don't know what signal is what.
>
>As usual, any help is appreciated.
>
>TIA
>
>Julian
Find thee the schematic for LPV11 as that is the only document I know of
that says what pins on J1 are what. I did One years ago and that was
what I had to do back then. Also there are jumpers that need to be correct
as that board would drive LP2x, LP05, and LA180 and LN01 printers
(data products parallel). Correctly wired any of the Centronics parallel
printer equivilents used with the XT class stuff (even an HP4L) work well
with it. It is otherwise trivial thing.
If memory serves that LAV-11 had the same pinout of it's J1.
Allison
OK, I'm trying to build myself a hookup for an M8027(LPV11) to run to my
distribution panel.
I've done some reading, and it is clear that this is a Centronics
compatible card, so I have the right one.
Does anyone know the pinout for this device? I'm confused. I know you
can use other printers with this card, and I'm just looking to do raw
text to an old Panasonic dot matrix printer - but I don't know what
signal is what.
As usual, any help is appreciated.
TIA
Julian
At least some of the Alphas have a failsafe jumper & disk, too, that allows you to recover from failed flashes. Set the jumper, put the disk in, and you can try again.
I've also got an Amiga 4000T, and I just had a *weird* thought (and coming
>from someone who knows almost nothing about Amigas, that could be a *bad*
thing...)
It looks like there's 1 slot on the 4000T motherboard that might be an ISA
slot - is it? If so, will a plain-jane NE2000 compatible network card work
on the thing? (I would think there's drivers for something like that... but
who knows at this point.)
Here's the *even* weirder idea: I have access to an ISA-based PCMCIA kit,
which gives you to front-accessible PCMCIA slots. Are there Amiga drivers
for any PCMCIA ethernet kit? (I'm also thinking of using it to access
Compact Flash drives... ;-)
IIRC, I have AmigaOS 3.5 on the thing. I looked it up quite a while ago,
but as the box has very little on it WRT software & whatnot, no way to back
it up (beyond floppy, and I ain't doin' that), and no easy way (other than
burning CDs) to get stuff on it, I've not really been "motivated" enough to
diddle with it as of yet.
Anyway, just an odd thought...
Laterz,
Roger "Merch" Merchberger
--
Roger "Merch" Merchberger | "Profile, don't speculate."
SysAdmin, Iceberg Computers | Daniel J. Bernstein
zmerch at 30below.com |
>> 1016 into 8388607 is 8256.50... 12 into 8256.5 is 688.
>> 688 feet? I'm missing something here. It did say plotter-units,
>> not user = units.
> Yes, I get that too. Sounds far too large. Maybe that's the limits
> of the internal control electronics (that is, the plotter will accept
> vaules that large without giving an error), even though they are
> phyiscially ridiculous.
Don't forget continuous roll plotters can plot images that are only
physically limited by the media length, (I can't remember if the
one at Uni was HP or not but it was a huge A0 wide roll type) in that
case an image of more than 100 feet long is not unreasonable (e.g. hot
air balloon panel patterns) and 688 feet doesn't seem quite that big.
Lee.
..
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Hi list,
You may remember the big stack of HP85s/HP86Bs I pulled from a
dumpster a few months ago.
They've been stored away safely since then, and now I'd like to get
started testing them so that I can get them sold. Tony recommended
running the power supplies on a dummy load to make sure that none of
them are duds. I have a handy bag of Big Resistors that I can make
dummy loads out of, however, (in an 86B at least, I've not been into
the 85s yet) there's a 10-conductor cable coming out of the PSU and
I've no idea what sort of load it might want to see and on which pins.
Googling for the service manual hasn't been productive.
Can anyone advise? I have the basic tools (multimeter etc., and some
cantankerous old oscilloscopes) but don't have any experience doing
this sort of thing.
Thanks,
Ed.
Hi
My experience with the variac is that it is too uncontrolled.
The idea of using a light is good but what wattage should
one use. Remember that the light has quite a bit of positive
temperature coefficient. When cold the resistance is a lot
less then when glowing.
If it is a switcher, you shouldn't use a variac at all.
You should disconnect one lead of the capacitor and put
a series resistor to a power supply. I recommend using
a voltage on the supply of at least 50% of the rated voltage
and a resistor that if the cap is shorted will supply
a maximum of 10 ma to a low voltage cap that is about 1.5
inch diameter and about 3 inches long. Smaller caps should
have less current. Many computer capacitors may draw more that
10 ma as lower voltage, higher capacitance caps. If
after 10 or so hours at 10 ma, you don't see any change,
increase the current some. For high voltage capacitors,
you should limit to about 1 or 2 ma.
Even on a linear supply, I recommend disconnecting the
capacitor and bringing it up with a resistor and supply.
Switchers can blow up with too low a voltage. Most newer
supplies will be OK but you won't get good forming of
the output capacitors since the supply will remain
off until the voltage is high enough to start the switcher.
This usually means full voltage to the output capacitors.
For this and other reasons, I still recommend isolating
one of the leads of the cap and using the limited supply.
>From: "Robert Armstrong" <bob at jfcl.com>
>
>JC,
>
> AFAIK the issue with reforming old electrolytics is that the caps will
>have very high leakage currents until they reform. The goal is to limit the
>power dissipation of the cap to something low enough that it won't vent (or
>explode!) until it's recovered.
>
> Lots of people use Variacs for this purpose and they'll certainly do the
>job, but they don't give you any way to measure the leakage current. I
>prefer the simple technique of putting a light bulb in series with the AC
>side of the supply - when it's bright, the current is high and as it
>gradually dims and goes out, the current is low.
>
>> maybe leave a junk card in for load?)
>
> If it's a linear supply then it's probably happy without a load, and
>there's no sense in wasting even a junk board.
>
> If it's a switching supply then it depends on the design, but most likely
>it will require some kind of load on at least some of the outputs to
>maintain regulation.
>
>Bob
>
>> -----Original Message-----
>> From: cctalk-bounces at classiccmp.org
>> [mailto:cctalk-bounces at classiccmp.org] On Behalf Of J.C. Wren
>> Sent: Tuesday, December 06, 2005 7:13 AM
>> To: cctalk at classiccmp.org
>> Subject: Cap reformation question
>>
>>
>> I've got a system with a couple large electrolytics that
>> hasn't been
>> powered up in a number of years. I have a 5A Variac. What's the
>> typical procedure for the reformation process? Remove all cards (or
>> maybe leave a junk card in for load?), start the Variac at
>> 0V, increment
>> by 10V every so often? How long per step, and/or is a different step
>> suggested?
>>
>> I've seen lots of people say "you'll need to reform the caps,
>> first", but never a prodecure for it.
>>
>> --jc
>>
>>
>
>
>
