> > I have washed motherboards and cards (most are 386s or 486s) for
> > numerous times. No heated dry though. Just use a fan to
> blow air at it
> > overnight.
In printed circuit board production everything gets "dishwashed" after
wave soldering to remove flux, masks and junk. It is then baked in an
air oven. It's been 20 years since I've been around PC board production,
but as I recall it was a very hot water/acid/detergent wash.
So, it's nothing that your components haven't seen before.
Some things to remember -
The cleaner the water the better so maybe put a charcoal filter on the
washer line,
City water has some chlorine and has a tiny risk of bleaching,
All automatic dishwasher detergents have lots of chlorine and might
bleach (great for discolored plastics),
Powdered automatic dish detergent has silicone dioxide (sand) and will
scour your boards,
Because of the above 2 items you might want to use "hand" dishwashing
detergent, but not much since it will foam,
Since isopropanol will aggressively bond with water molecules I like to
chase the water off with an isopropanol rinse (pure, if you can get it,
or 90% sold in drug stores),
Follow with some kind of gentle bake (direct sun on a warm day, hair
dryer, oven, fans). The isopropanol rinse is good for drying since
alcohols evaporate easily. Iso is used by "re-work" technicians to
remove flux on boards that are touched up by hand, so iso is generally
safe, but might remove ink printing on labels and might attack the label
glue.
Thanks for sharing your day in the shack with us, Charles.
I am glad to read that I am not the only one who can cut a
wire without any intention of wanting to do that :-)
Due to other obligations, I have not been able to swap the
RL11 controller ... Ahh well, it's almost weekend!
- Henk, PA8PDP.
> -----Original Message-----
> From: cctalk-bounces at classiccmp.org
> [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Charles
> Sent: vrijdag 6 januari 2006 1:25
> To: cctech at classiccmp.org
> Subject: Re: RL02 write faults, found it, now how to fix it?
>
> I spent an interesting day in the shack today. After blowing
> off the dust, I found that my old 7D01 logic analyzer won't
> trigger on the word recognizer but Ch. 0 would trigger, so I
> started hooking it up to the RL02 logic board and R/W boards
> using the drive error as a post-data trigger and looking
> backwards from there.
>
> Eventually I learned that Write Gate and Write Data are being
> correctly asserted, and the data bursts continue for 500+ uS (one
> sector) beginning a couple of uS after the Sector pulse. But
> approximately 4 to 6 uS after the Write Gate opens, and
> before the data could even begin (10+ uS), the DL5 DRIVE ERR
> signal asserts!
> I worked around the loop from there and found that the
> *first* thing to go wrong was the Write Data Error Latch
> ('LS279, E6 on logic board) which was setting its output pin
> 13 (DL5 WR DATA ERR H). This fatal error signal then latches
> DL5 DRIVE ERR H via the other "glue" logic and prevents any
> further action.
>
> But the R/W board that generates Write Data Error Pulse was
> *not* telling the latch to set! There is a 6K8 resistor to +5 and a
> 0.0056 uf cap to ground as a delay (set only) in the error
> circuit (a time constant of 38 uS) so to reach a logic 1
> (2.0v) would take considerably longer than 6 uS anyway.
>
> Further exploration with the logic analyzer on "high" speed (20
> ns/tick) shows that on the 'LS279 pin 15 (the latch input,
> WRITE DATA ERROR PLS L) there is a small (~180-200 ns) low
> pulse with a 20 ns glitch in the middle. It is NOT evident to
> the logic analyzer when examining the signal's source on the
> R/W board, (Write Data Error Detector E3, 7404 pin 8). But
> it's enough to set the WDE latch all right!
>
> Right about then, sparks started flying from the brush area
> of the spindle motor and the drive faulted on its own and spun down.
> Holy crap! =:^O
>
> I pulled the circuit breaker fast and gently spun the motor
> and could hear scraping noises. I figured the brushes were
> shot or something, so I took the two nuts off the through
> bolts. Of course the end housing wouldn't come off, way too
> tight a fit, and I didn't want to pull the blower motor. With
> a bright light I could see a piece of something blue sticking
> up, so I pulled it out with a pair of fine needlenose pliers.
> It was the tip of one of my logic analyzer leads that had
> sneaked into the vent holes unknown to me, and been cut off
> by the armature turning! I put the nuts back on (of course I
> dropped the second one inside the motor and had to fish that
> out too), crossed all my fingers and flipped the breaker. It
> spun right up and has been working fine since. Whew.
> Never a dull moment in Murphy's Laws.
>
> Anyhow, there is a 330 pf deglitching cap near the input to the
> 'LS279 but obviously it's not adequate. I need to put a fast
> scope on the line and see what the edges actually look like.
> Some resistive termination may be needed. This is on a very
> short ribbon cable to J6, about 6", inside the drive, and the
> chassis ground wires to each board are connected. Or maybe
> the Berg connector on one end is defective in the ground
> lead. More as I discover it.
>
> -Charles
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der Mouse wrote:
>> No. With reverse engineering you *understand* the design.
> I get that by reading the docs, the schematic and using the machine.
With real docs (such as schematics) you don't _need_ to
reverse-engineer. Reverse engineering, at least as I learned to use
the term, refers to the process of deducing that kind of information
>from the device.
der Mouse
Real documents are wonderful but rarely available. In my field (hard
drives) the schematic is useless. What we really need to understand is the
manufacturing process, especially for heads and media. Those are "black
magic" processes that defy instant analysis. Worse, they require enormously
expensive test equipment and high skill levels.
Decapping an IC and stripping off the layers is a major piece of
engineering. Measuring the flying height of a GMR head flying closer to the
media than the wavelength of visible light can take a small team of
engineers and lots of money.
And then there is the problem some of you have encountered: how to reverse
engineer code when it is embedded with the processor in an IC package that
has no external memory access?
Reverse engineering to me is: to deduce enough information to duplicate the
device, including manufacturing processes.
Billy
Does anyone have one of these?
They are a VAXstation based workstation with a fancy E&S graphics
subsystem in them. They had a limited release around 1988, which was
when I saw one in operation when E&S did a dog-and-pony show at the
UofU.
--
"The Direct3D Graphics Pipeline"-- code samples, sample chapter, FAQ:
<http://www.xmission.com/~legalize/book/>
Pilgrimage: Utah's annual demoparty
<http://pilgrimage.scene.org>
I'm looking to get a nice IBM Selectric typewriter - for typewriter,
not computer console, use. Not too picky as to typeball etc., but
if someone wants to tell me what to look for and what to avoid, I'm
all ears.
In the past I've used both Selectric II's and III's and can't
say I prefer one over the other. I am looking to keep it for many
years with only light to moderate use so reliability/parts availability
is somewhat important.
Anyone want to recommend a US (or Washington DC) area dealer who
stands above the rest? Or should I just take my chances on E-pay?
Is there a more appropriate forum for asking about typewriters?
Tim.
I spent an interesting day in the shack today. After blowing off
the dust, I found that my old 7D01 logic analyzer won't trigger on
the word recognizer but Ch. 0 would trigger, so I started hooking
it up to the RL02 logic board and R/W boards using the drive error
as a post-data trigger and looking backwards from there.
Eventually I learned that Write Gate and Write Data are being
correctly asserted, and the data bursts continue for 500+ uS (one
sector) beginning a couple of uS after the Sector pulse. But
approximately 4 to 6 uS after the Write Gate opens, and before the
data could even begin (10+ uS), the DL5 DRIVE ERR signal asserts!
I worked around the loop from there and found that the *first*
thing to go wrong was the Write Data Error Latch ('LS279, E6 on
logic board) which was setting its output pin 13 (DL5 WR DATA ERR
H). This fatal error signal then latches DL5 DRIVE ERR H via the
other "glue" logic and prevents any further action.
But the R/W board that generates Write Data Error Pulse was *not*
telling the latch to set! There is a 6K8 resistor to +5 and a
0.0056 uf cap to ground as a delay (set only) in the error circuit
(a time constant of 38 uS) so to reach a logic 1 (2.0v) would take
considerably longer than 6 uS anyway.
Further exploration with the logic analyzer on "high" speed (20
ns/tick) shows that on the 'LS279 pin 15 (the latch input, WRITE
DATA ERROR PLS L) there is a small (~180-200 ns) low pulse with a
20 ns glitch in the middle. It is NOT evident to the logic
analyzer when examining the signal's source on the R/W board,
(Write Data Error Detector E3, 7404 pin 8). But it's enough to set
the WDE latch all right!
Right about then, sparks started flying from the brush area of the
spindle motor and the drive faulted on its own and spun down.
Holy crap! =:^O
I pulled the circuit breaker fast and gently spun the motor and
could hear scraping noises. I figured the brushes were shot or
something, so I took the two nuts off the through bolts. Of course
the end housing wouldn't come off, way too tight a fit, and I
didn't want to pull the blower motor. With a bright light I could
see a piece of something blue sticking up, so I pulled it out with
a pair of fine needlenose pliers. It was the tip of one of my
logic analyzer leads that had sneaked into the vent holes unknown
to me, and been cut off by the armature turning! I put the nuts
back on (of course I dropped the second one inside the motor and
had to fish that out too), crossed all my fingers and flipped the
breaker. It spun right up and has been working fine since. Whew.
Never a dull moment in Murphy's Laws.
Anyhow, there is a 330 pf deglitching cap near the input to the
'LS279 but obviously it's not adequate. I need to put a fast scope
on the line and see what the edges actually look like. Some
resistive termination may be needed. This is on a very short
ribbon cable to J6, about 6", inside the drive, and the chassis
ground wires to each board are connected. Or maybe the Berg
connector on one end is defective in the ground lead. More as I
discover it.
-Charles
Tony Duell wrote:
> About 20 years ago, there was a Fischertechnik robotics kit. This
> contains the usual blocks, gears, etc, 2 small motors, 3 lamps, an
> electromagnet, 8 switches and 2 pots. And no other electonic parts.
>
> There were various interfaces sold for this, at the time they were
> very expensive and not suitable for the machines I had. So I did
> the obvious thing and boilt my own...
I know we have a similar unit for the Commodore C64. My father bought
it since he had both Fischertechnik stuff and a C64, but I don't
think we ever had the robotics kit you mention. Using the interface
just to switch two or three motors on and off doesn't seem that
interesting, so perhaps he also thought of it more like a general
purpose interface.
Even more stuff to try out some day - wish me a long life...
--
Arno Kletzander
Stud. Hilfskraft Informatik Sammlung Erlangen
www.iser.uni-erlangen.de
Telefonieren Sie schon oder sparen Sie noch?
NEU: GMX Phone_Flat http://www.gmx.net/de/go/telefonie
> Technical -- Reverse Engineering.
> Layman -- Piracy.
Significant difference- in reverse engineering you copy what something does, in piracy you copy what it is.
Hello folks,
hopefully all of you enjoyed your holidays and festivities.
> > One of the problems with old Selectrics is eventually the neoprene
> > drive belt deteriorates and breaks. I'm no Selectric repairman, but
> > a peek inside a nice wide-carriage Selectric III that I've got
> > stashed away looks like replacement of said belt is a major
> > operation and probably not worth the trouble.
Woohoo - good news, that (<<Irony). I've got about five of those IBM
typeball critters in my vicinity, all gifts from grammar school and
University; I don't know if the term "Selectric" applies to those
(none of them says so on the outside), but for the record, there are:
Qty. Model top shell base pan Keys
--------------------------------------------
1 50 pwd. blue black black
2 82c brick red brick red grey
1 82c greenish greenish grey
1 196c brick red black black
I "hope" one of the red 82s is a bit smaller than the other (and the
green) one (else I wouldn't see much of a point in keeping both), but
I haven't compared them side-by-side yet. I think they're all strictly
electro-mechanical except for the Model 50, which has a circuit board
in the base pan, a code key and some kind of lever switch to the left
of the keyboard, and unfortunately at the moment a broken belt inside.
In my case it's not the one from the motor to the drive shaft, but the
one driving the carriage spindle from the reversing clutch.
Also, how interchangeable are type balls among those machines? The blue
one was the only one to come without a ball, the 196c has one with
yellow top lettering and each of the others one with white, and I've
got spares/other fonts of both kinds.
Tony Duell wrote:
> I have never seen inside a Selectric, but I've heard that to change one
> of the belts you have to remove the main shaft, which is a major
> operation.
It certainly looks like a lot of work in mine; I also fear there might be
adjustments involved but I haven't tried to obtain a service manual yet.
> I was told that if you do this, slip 2 belts over the shaft and tape
> one to the side of the chassis out of the way. Next time it breaks,
> work that spare one onto the pulleys.
That sounds like a perfectly sane approach, provided there's enough space
in there so I can keep the belt out of the way. Thanks for suggesting this
before I attack the problem.
Yours sincerely,
--
Arno Kletzander
Stud. Hilfskraft Informatik Sammlung Erlangen
www.iser.uni-erlangen.de
10 GB Mailbox, 100 FreeSMS/Monat http://www.gmx.net/de/go/topmail
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