Re: Stuffing boards with pulled QFP chips

[Chuck Guzis via cctalk]

On 03/31/2017 06:15 PM, Jon Elson via cctech wrote:

> I have a project I do from time to time using 128-lead 14mm TQFPs
> with 0.4mm lead spacing. I use a stereo zoom microscope with a
> home-made LED ring light. First, I rub the pads with a pencil eraser
> to remove oxidation caused by reflow temps on the rest of the board.
> I put a tiny dab of solder on two pads at opposite corners. I then
> place the chip in place and reflow those pads.  If the alignment is
> not good enough, I can "walk" the chip a bit by reflowing one, then 
> the other pad.  Then, I apply liquid flux to the rows of leads with
> a wire dipped in the flux. And, then solder down the rows with a
> fine-tip soldering iron.  If a bridge develops, solder wick fixes
> it.

There are plenty of good Youtube videos describing this.  I use pretty
much the same method, but start off with just a binocular loupe and then
finish with a stereo microscope for final inspection.

The soldering  iron tip that works best for me is a rather broad chisel
tip.  I leave the fine tips for other work.

--Chuck

Re: Stuffing boards with pulled QFP chips

[Jim Brain via cctalk]

On 3/31/2017 12:51 PM, allison via cctech wrote:

Is this something that an experienced hand can manually do?


I can verify that it is indeed possible.  I lay down xc95144xl-tq100s 
all the time with my iron and some flux and some wick, and I get nearly 
100% rates.  My eyes are not what they used to be either, so a 
magnifying glass and a light touch makes all the difference.


I am sure others on list are even better than I, but I recommend flux, 
place the IC, and then carefully set the board aside to dry. The flux 
will dry, turn into "glue" (as the alcohol evaporates), and that helps 
with soldering.


Jim

Re: Stuffing boards with pulled QFP chips

[Jon Elson via cctalk]

On 03/31/2017 06:28 PM, allison via cctech wrote:


Is this something that an experienced hand can manually do?

Yes, definitely.  100 lead PQFP is perfectly doable if the lead pitch is not 
insanely small.  It takes a good fine tip soldering iron (mine is a Weller with 
a PTS tip), fine solder (preferably real, i.e., 63/37 non-PC solder).  Liquid 
flux is a big help, as is a magnifier and bright light or modest magnification 
microscope.

If you have to do a couple of dozen boards this gets very tedious, but for 
5-ish it isn't a big deal.


I have a project I do from time to time using 128-lead 14mm 
TQFPs with 0.4mm lead spacing.
I use a stereo zoom microscope with a home-made LED ring 
light. First, I rub the pads with a pencil eraser to remove 
oxidation caused by reflow temps on the rest of the board.  
I put a tiny dab of solder on two pads at opposite corners.
I then place the chip in place and reflow those pads.  If 
the alignment is not good enough, I can "walk" the chip a 
bit by reflowing one, then the other pad.  Then, I apply 
liquid flux to the rows of leads with a wire dipped in the flux.
And, then solder down the rows with a fine-tip soldering 
iron.  If a bridge develops, solder wick fixes it.


Jon

Re: Stuffing boards with pulled QFP chips

[allison via cctalk]

On 03/31/2017 02:00 PM, Paul Koning wrote:
>> On Mar 31, 2017, at 1:51 PM, allison via cctech  
>> wrote:
>>
>> On 03/31/2017 06:32 AM, David Griffith via cctalk wrote:
 I'm down to the last few P112 boards for sale and am pondering
 another run of them because demand is steady.  One of the biggest
 challenges for the last run was getting the QFP-packaged 100-pin
 chips[1] in a state such that the pick-and-place robot wouldn't throw
 a fit about slight differences in lead position.  The stuffing house
 insisted that I send them new chips.  Pulls, though they looked
 perfectly okay to me, were not acceptable.  Does anyone here know
 anything about pick-and-place robots using pulled 100-pin QFPs,
 particularly a stuffing house that can work with such chips and not
 screw up?

 [1] The now-obsolete super-io chips


>> Is this something that an experienced hand can manually do?
> Yes, definitely.  100 lead PQFP is perfectly doable if the lead pitch is not 
> insanely small.  It takes a good fine tip soldering iron (mine is a Weller 
> with a PTS tip), fine solder (preferably real, i.e., 63/37 non-PC solder).  
> Liquid flux is a big help, as is a magnifier and bright light or modest 
> magnification microscope.
>
> If you have to do a couple of dozen boards this gets very tedious, but for 
> 5-ish it isn't a big deal.
>
>   paul
>
So happens I'm fully equipped on all counts.  Including the PTS tip. 
However my preference
for years has been the PTA7K (WTCP60) which is 1/4" wide!  Gets a few
pins done at a time... ;)

I've not gone over to the Rohs side, most of the solders are not fun to
work with though a
few have very active fluxes and solder aluminium well.   So its Kester
44 in 10 and
20 mil (inch mil) diameters.

I've done more than a few AD537 and similar Blackfin CPUs with their 288
BGA package that's
a challenge to pull and replace.

Allison

Re: Stuffing boards with pulled QFP chips

[Paul Koning via cctalk]

> On Mar 31, 2017, at 1:51 PM, allison via cctech  wrote:
> 
> On 03/31/2017 06:32 AM, David Griffith via cctalk wrote:
>>> 
>>> I'm down to the last few P112 boards for sale and am pondering
>>> another run of them because demand is steady.  One of the biggest
>>> challenges for the last run was getting the QFP-packaged 100-pin
>>> chips[1] in a state such that the pick-and-place robot wouldn't throw
>>> a fit about slight differences in lead position.  The stuffing house
>>> insisted that I send them new chips.  Pulls, though they looked
>>> perfectly okay to me, were not acceptable.  Does anyone here know
>>> anything about pick-and-place robots using pulled 100-pin QFPs,
>>> particularly a stuffing house that can work with such chips and not
>>> screw up?
>>> 
>>> [1] The now-obsolete super-io chips
>>> 
>>> 
>> 
> Is this something that an experienced hand can manually do?

Yes, definitely.  100 lead PQFP is perfectly doable if the lead pitch is not 
insanely small.  It takes a good fine tip soldering iron (mine is a Weller with 
a PTS tip), fine solder (preferably real, i.e., 63/37 non-PC solder).  Liquid 
flux is a big help, as is a magnifier and bright light or modest magnification 
microscope.

If you have to do a couple of dozen boards this gets very tedious, but for 
5-ish it isn't a big deal.

paul

Re: Stuffing boards with pulled QFP chips

[allison via cctalk]

On 03/31/2017 06:32 AM, David Griffith via cctalk wrote:
>>
>> I'm down to the last few P112 boards for sale and am pondering
>> another run of them because demand is steady.  One of the biggest
>> challenges for the last run was getting the QFP-packaged 100-pin
>> chips[1] in a state such that the pick-and-place robot wouldn't throw
>> a fit about slight differences in lead position.  The stuffing house
>> insisted that I send them new chips.  Pulls, though they looked
>> perfectly okay to me, were not acceptable.  Does anyone here know
>> anything about pick-and-place robots using pulled 100-pin QFPs,
>> particularly a stuffing house that can work with such chips and not
>> screw up?
>>
>> [1] The now-obsolete super-io chips
>>
>>
>
Is this something that an experienced hand can manually do?

Of all the CP/M platforms its one of the few I haven't done.  But
it keeps popping after I've long figured its long gone.

I'm not afraid of SMT as I proto using 0603 and 0402 parts
at uhf/microwave freehand.

Baving delt with layouts for BGA and large pinout devices usually getting
fiducial marks on the board so it can locate and position without
optical works.
One time the board designer messed up and we had to use existing fixed
points
for that.  PITA but it worked. After that I got into the board layout
bit and DFM.


Allison

Re: Apple 1, Commodore 65, Enigma Machine, Inventor of C++

[Sam O'nella via cctalk]

 Original message From: Christian Corti via cctalk 
 Date: 3/29/17  3:29 AM  (GMT-06:00) To: Evan Koblentz 

>On Tue, 28 Mar 2017, Evan Koblentz wrote:
>> "What do an Apple 1, Commodore 65, >>Enigma Machine, and the inventor of C++ 
>> all have in common?"

>They're just overestimated pieces of junk ;-) >(and C++, not its inventor)
>[duck...]

Said to most of us about our hobby and collections?
We're supposed to be challenging that battle, mate. Not feeding it ;-)

RE: Trip to CHM - Hotel/Restaurant Advice

[Sam O'nella via cctalk]

I thought the Vintage Computer festival west link might have recommended hotels 
but I couldn't find anything for you.
I did a similar trip but needed to be quite a few hours south for my actual 
destination. I didn't find a very cheap hotel either, and the under $100 one I 
did find near long Beach was quite underwhelming. The type my wife wouldn't 
have let us stay at.
What I did find more useful was a super small rental car for $98 that did give 
me much more freedom to get around a few sites (and Weird Stuff).  It was 
highly recommended not to sleep in the car though so best luck.
I explored airbnb but it seems to mirror closely to hotel prices and a 
surprisingly large amount want a 2 day stay.
But CHM is definitely a fun trip. I have a quite large collection for home 
computing so I wasn't sure how long I'd stay occupied but between the demos and 
tours and just perusing I definitely could have enjoyed more than the afternoon 
I spent.
Best recommendations were ubering or rental car then get a hotel in your price 
range but don't worry as much about location. Or get one near the train.

Intellivision reset switch

[Jules Richardson via cctalk]

Can anyone who's been inside an Intellivision confirm that there's supposed 
to be a little foam disc beneath the reset switch plate?


I picked a system with a box of cartridges up earlier, half expecting the 
machine to be dead (I was figuring it was going to be a blob of 
easily-dead-after-so-many-years custom logic inside, but it's more like a 
"real computer" in nature). It *was* dead, but the [initial, at least] 
issue seems to be that the reset switch consists of a metal plate which is 
supposed to make contact with the PCB when pressed - and presumably is held 
away from the PCB by something when at rest. Except that there's no 
"something" in this machine - with the machine the right way up, the plate 
is free to contact the PCB, holding it in permanent reset.


I'm guessing it was a blob of foam, which has deteriorated, but maybe it 
was a metal spring, or a piece of u-shaped plastic etc.


cheers

Jules

Re: Trip to CHM - Hotel/Restaurant Advice

[Chuck Guzis via cctalk]

On 03/31/2017 11:17 AM, Al Kossow via cctalk wrote:
> 
> 
> On 3/30/17 9:29 PM, Chuck Guzis via cctalk wrote:
> 
>> In the late 70s, on Evelyn in Sunnyvale, near Wolfe, I believe.
> 
> That would be the original Halted location, Evelyn and Wolfe
> 
> Halted moved to roughly laurence and central, then moved to 3051
> Corvin last year.
> 
> The previous building was demolished last week. The entire block is
> gone all the way from central to keifer, including the building that
> was ACE Electronics on Keifer.

That's a shame.  One thing that Sunnyvale and Santa Clara offered was
lots of inexpensive "incubator" space.

I think that soaring prices on industrial rental space was what
eventually forced Dan (Haltek) out of his digs on Linda Vista in MV.

He had another outfit in Santa Clara, "Redwood Electronics", but that
seems to have turned to dust at about the same time.

Things come and go, though.  Where Sun was  is now Google.  Tear-downs
are the thing in older residential Mountain View and Palo Alto.

I remember when nobody but hippies and horse people lived in Los Altos
Hills on  gravel-paved roads.


--Chuck

OT: PCI Ethernet or USB 2.0 ethernet?

[W2HX via cctalk]

Friends,

I have an instrument that has an intel motherboard with 400 MHz FSB PCI (not 
PCI-e). It has a 100 mbps Ethernet card and it would be very useful to get 
faster networking. The chassis of this instrument is such that I cannot fit a 
traditional PCI 1GB Ethernet card (I've tried). So I will have to go wifi 
(which I can make fit because I can remotely locate the wifi antenna). I have 
802.11ac both 2.4 and 5 GHz available. While it certainly won't get as good a 
throughput as a dedicate GB Ethernet card, this is my only option.

The question is, whether you think I would be better off using PCI wifi card or 
a USB-wifi adapter. I should mention the USB on this instrument is USB 2.0, the 
spec for which claims up to 480 Mbps.   Anyone have an opinion which might get 
me better results? The wifi infrastructure is one constant in this scenario, 
just looking to see pci- or usb-based wifi card.

Since this is wildly off topic, please respond to me directly so as not to 
bother everyone else :)
w...@w2hx.com

Thanks
Eugene

WTB: DEC VR241 or HP 6000 670H (or 670XP)

[Cameron Kaiser via cctalk]

I'm looking for two items:

A VR241 to use with my DEC 380 as a colour head (even better if you have the
cable and a spare LK201, since I'm down to my last working keyboard). The
VR201 isn't cutting it anymore and I don't think I can use my VR260 with this.

An HP 6000 670H hard disk (the big one for the 300 series). XP even better,
but I've done just fine with an H.

Please include what price you're asking.

Thanks!

-- 
 personal: http://www.cameronkaiser.com/ --
  Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckai...@floodgap.com
-- Communism doesn't work because people like to own stuff. -- Frank Zappa 

Re: Trip to CHM - Hotel/Restaurant Advice

[Al Kossow via cctalk]

On 3/30/17 9:29 PM, Chuck Guzis via cctalk wrote:

> In the late 70s, on Evelyn in Sunnyvale, near Wolfe, I believe.

That would be the original Halted location, Evelyn and Wolfe

Halted moved to roughly laurence and central, then moved to 3051 Corvin
last year.

The previous building was demolished last week. The entire block is gone
all the way from central to keifer, including the building that was ACE 
Electronics
on Keifer.

Re: Cross-talk square-wave?

[Noel Chiappa via cctalk]

> From: Brent Hilpert

> I don't have a full enough picture of the circuit and circumstances to
> provide a definitive suggestion but, some principles:
> ...
> It's not clear C-coupling is what's going on here (the wave shape looks
> pretty sharp for what I understand of the circuit/layout).

Thanks for taking the time for that detailed message.

I suspect, however, that Jon Elson has nailed it (thanks Jon :-); if that's
what's happening, it explains why we couldn't understand what the devil was
going on!

> (You've mentioned both 470K and 270K for the R, could make a difference
> to the analysis).

Yeah, that was just a typo; going from memory.

  Noel

Re: Cross-talk square-wave?

[Jon Elson via cctalk]

On 03/31/2017 07:10 AM, David Bridgham via cctalk wrote:

Don't trust ANYTHING!  Recent Xilinx FPGAs have permanent "weak
keepers" on all pins, they can not be turned off.
What this is is a non-inverting receiver on the pad, that is driving
back to the pad with about a 50K Ohm resistor.
Plays hob with analog stuff like crystal oscillators.  The weak keeper
would PERFECTLY explain your square wave!
When it gets a narrow pulse to high, it holds the line high.  When it
gets a narrow pulse to low, it will switch to holding the line low.
So, if you are using a Xilinx FPGA of recent vintage, or some of their
CPLDs, they will do exactly this.

Looks like we have an explanation then.  We're using an XC7A75T-CSG324,
a Xilinx Artix 7 series FPGA.  Thank you very much.


Yup, that definitely has such a feature.  I think there are 
some Xilinx knowledgebase articles on the specifics of 
certain family's pad options and how to deal with them in 
pseudo-analog functions like crystal oscillators, switch 
debounce, etc.


Jon

Re: Stuffing boards with pulled QFP chips

[Jon Elson via cctalk]

On 03/31/2017 06:32 AM, David Griffith via cctalk wrote:


I'm down to the last few P112 boards for sale and am 
pondering another run of them because demand is steady.  
One of the biggest challenges for the last run was getting 
the QFP-packaged 100-pin chips[1] in a state such that the 
pick-and-place robot wouldn't throw a fit about slight 
differences in lead position.  The stuffing house insisted 
that I send them new chips.  Pulls, though they looked 
perfectly okay to me, were not acceptable.  Does anyone 
here know anything about pick-and-place robots using 
pulled 100-pin QFPs, particularly a stuffing house that 
can work with such chips and not screw up?


[1] The now-obsolete super-io chips


There USED to be outfits that recycled chips.  They had some 
system to clean and replate/reflow the leads and align 
them.  The good ones could counterfeit them for new, you 
absolutely could NOT TELL they were not new from the 
factory.  I have no idea if any of these outfits still 
exist.  Probably they do, in China!


My P&P would have no problem, it uses mechanical alignment 
jaws.  But, modern P&P use vision to locate the solder area 
of the leads and then position using those coordinates.  So, 
anything that changes the reflection of the leads or causes 
slight misalignment would cause an alignment failure.


Jon

Re: Cross-talk square-wave?

[David Bridgham via cctalk]

> Don't trust ANYTHING!  Recent Xilinx FPGAs have permanent "weak
> keepers" on all pins, they can not be turned off.
> What this is is a non-inverting receiver on the pad, that is driving
> back to the pad with about a 50K Ohm resistor.
> Plays hob with analog stuff like crystal oscillators.  The weak keeper
> would PERFECTLY explain your square wave!
> When it gets a narrow pulse to high, it holds the line high.  When it
> gets a narrow pulse to low, it will switch to holding the line low. 
> So, if you are using a Xilinx FPGA of recent vintage, or some of their
> CPLDs, they will do exactly this.

Looks like we have an explanation then.  We're using an XC7A75T-CSG324,
a Xilinx Artix 7 series FPGA.  Thank you very much.

Stuffing boards with pulled QFP chips

[David Griffith via cctalk]

I'm down to the last few P112 boards for sale and am pondering another run 
of them because demand is steady.  One of the biggest challenges for the 
last run was getting the QFP-packaged 100-pin chips[1] in a state such 
that the pick-and-place robot wouldn't throw a fit about slight 
differences in lead position.  The stuffing house insisted that I send 
them new chips.  Pulls, though they looked perfectly okay to me, were not 
acceptable.  Does anyone here know anything about pick-and-place robots 
using pulled 100-pin QFPs, particularly a stuffing house that can work 
with such chips and not screw up?


[1] The now-obsolete super-io chips


--
David Griffith
d...@661.org

A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?

Re: Trip to CHM - Hotel/Restaurant Advice

[Eric Smith via cctalk]

On Thu, Mar 30, 2017 at 5:05 PM, Rich Alderson via cctalk <
cctalk@classiccmp.org> wrote:

> and what there are are not
> easily within walking distance of good food (In 'n' Out does not qualify).
>

Them's fightin' words!

Re: Trip to CHM - Hotel/Restaurant Advice

[Cameron Kaiser via cctalk]

> Remember Haltek in Mountain View?  (wasn't it at the dead end of Linda
> Vista?  I bought my Tek 465 there.)

You don't mean Halted Electronics, do you? That should still be around.

I was passing through Sunnyvale on my way back south and picked up some
useful doodads at Weird Stuff, though it took an hour to find them. I'm not
sure if that was a good use of my time. ;)

-- 
 personal: http://www.cameronkaiser.com/ --
  Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckai...@floodgap.com
-- A service of the Department of the Redundancy Department service. --