Fran's Writings on Design and Engineering
Page 7

Return to the Design Writings Main Menu Page

Subscribe to my YouTube Channel!
List of articles on this page:
(November 2013 - December 2013)
Apollo Saturn V LVDC Board Teardown, Part 3
Apollo Saturn V LVDC Board Teardown, Part 2
Fran's Space Attack! Make Your Own Video Multicade 
The Apollo Hoax Conspiracy Epidemic 
Ghost In The Machine
FranLab
Music Gear Builders Group Meeting
Making instructional videos, writing articles, and maintaining my blog are all quite expensive.  Please help me continue to make more and better content by becoming a contributor!  Please support Fran's Blog - 
For Science!
Follow Fran on Twitter:


 

Subscribe to Fran on YouTube:

- LVDC Project Update -
(December 26, 2013)
Dave Jones at EEVBlog receives the LVDC page assembly board!


 
 
 
Apollo Saturn V LVDC Board Teardown, Part 3
(December 2013)



In the (final) conclusion for my part of the LVDC Project I went back to the workbench to find the best way of depotting these logic devices without destroying them, and if I could do that successfully then I would try to verify the circuits inside by comparing them against the available data in several documents found online. 


 


Here I have chiseled the top off of an AA type package.
 


I used a soft plastic toothpick this time, with a gum brush attached to one side, and under a magnifier I very delicately removed the silicone potting compound from around the tiny dies inside. 
 


Success!  I cleared out the potting of the AA type logic device package without dislodging any of the dies from the traces.


A close up view of the top side of the cleared AA logic device.  It contains 4 dies, all of them common anode dual diodes.
 


A close up view of the bottom side of the AA logic device, where I have carefully pulled back some of the silicone coating with fine tweezers to reveal the traces.  Unfortunately, exposure to the elements has taken its toll -  moisture had penetrated the seal and the resistive film inside had completely disintegrated.  I could not get a reading on the resistors.
 


An INV type logic device package decapped.
 


The INV type logic device cleared with much patience.
 


A close up view of the top side of the INV type logic device.  The die on the upper right hand side is an NPN transistor, the rest are dual common anode diodes.
 


 Here I made a working model of the AA type quad input diode logic AND gate using (4) #4148 signal diodes and a 2.2K pull up resistor.  It works very well!
 

Now I will pass the board along to another engineer in our community, and they will add their skills to deconstructing this relic, and perhaps revealing more of its secrets.  To be continued!


 

 
 
Apollo Saturn V LVDC Board Teardown, Part 2
(November 2013)


 

Chip type #321 was the first to come off the LVDC board, and I found that the coating on the underside which was covering the resistive elements was in fact a thin rubbery coating of some kind of silicone.  I successfully removed the coating by gently using a small screwdriver to distress the silicone, then brushed it off of the ceramic wafer with a medium bristle toothbrush.  Using my DMM I found the values to be very precise, and the mechanically trimmed deposited film resistors are indeed very accurate in value.

My first attempt to open one of these device packages was not elegant - I broke the thin ceramic top off of #321 in pieces, which revealed a pink putty-like silicone fill. 

Removing the potting I found that the package was empty - no traces, no semiconductors.  It seems that #321 is simply two resistors, nothing more.

This is the cleaned interior of a type #322 package - 
Possibly a bootstrapped transistor configured as a simple constant current source(?):

I used a sharp chisel to open each package by prying off the cover.

Inside each device package was a pink silicone based putty that filled the cavity.

I carefully picked away the filling to reveal the circuitry inside, but as it turned out my light touch was not light enough.  I accidentally dislodged many of the semiconductors from their mounts in the process.

Missing transistors.... Doh!  I found them in the potting I pulled out later.  Those traces are wide, but the mounting points on the semiconductors are microscopically small, just a few mils across at best.  Not much surface area for the solder joints.

Resistors on the underside of the AB type device package - I damaged the one on the far right while taking the silicone coating off.  This is much harder than it seemed to remove the potting without damaging the electronics. 

 The semiconductors are very small - here a normal pencil point is placed in view for scale.

 Close up of a transistor I inadvertently snapped off:

When chipping off the top cap of one of the device packages I dislodged a wafer slightly, and accidentally discovered that the leads on these logic device packages were actually held by spring tension to deposited metallic contacts on the bottom and top sides of the ceramic base wafer.  The leads are not soldered to the devices, but instead each making purely mechanical contact to the base wafer.  A conductive medium might be present in the clip part, but that should get further investigation by another engineer in the project. Another great reason why these page assembly boards were so very heavily conformal coated for flight - not just because of the liquid cooling throughout the LVDC, but it would also have been necessary to prevent the devices moving out of place due to the extreme vibration of the Saturn V in flight.

Close up of the spring clip leads still in place after I successfully pushed out a logic device package.

 


 
Fran's Space Attack! Make Your Own Video Multicade 
(November 2013)

So many people have asked about my Space Attack! cabinet and how to make a multicade so here is a simple overview of what you need to do.  A project like this has lots of details that you mostly have to work out yourself because of the differences in cabinets, monitors, game PCB pinouts, and controller options - but this video shows how to get started and the basics you will need to work out.  I built this cabinet in 2000 to run original arcade PCB game board pulls, but converted to multicade PCB in 2007. 

My old BiPlane on KLOV


 

Fran Plays Phoenix! 

Here I play a quick game of Phoenix on my custom built vertical Multicade.  Even though I have played this game since around 1980 I still utterly stink at it.  But it is still fun! 


 
 
The Apollo Hoax Conspiracy Epidemic 
(November 2013)

I am tired of the endless outpouring of videos from Apollo hoax nuts - time to rant!

Lunar Reconnaissance Orbiter photos of the Apollo Landing Sites - http://www.nasa.gov/mission_pages/apollo/revisited/#.UnayKlPSi9I 

YouTube is part of the problem - Here is a screenshot of the contrary keyword suggestions I mention for video uploads


 
Ghost In The Machine
(October 2013)

Hank expires unexpectedly on camera.   The Horror....  The Horror.


 
FranLab
(October 2013)

A sneak peek at my new workspace - FranLab!


 
Music Gear Builders Group Meeting 
(September 2013)

I joined a group of fellow builders to talk space, show off some cool gear, examine a genuine Saturn V engine component first hand, shoot the breeze, and even jam out a bit.  All good fun - and here are some assorted highlights.  Enjoy! 

Potofone Ribbon Mics - http://www.potofone.com/index.html
Ed's Cool Hand-Built Analog Instruments - http://potophonics.com/
Valclone Amps - http://www.valclone.com/HOME.html
The Lost Patrol - http://www.thelostpatrol.com/

Return to the Design Writings Main Menu Page

 Frantone Home  ||  About Frantone   ||   Contact  ||   Fransworld Daily Updates


©1994-2014 Frantone Electronics  All rights reserved.
All images and text are copyright Frantone Electronics.  No content of this website may be published or distributed without prior written permission from Frantone Electronics and any reproduction or manipulation of the content of this website for any purpose is strictly prohibited.