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F18A Installation GOTCHA! (well got me)


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#1 CantStopClicking OFFLINE  

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Posted Sun Jan 7, 2018 2:57 AM

I thought I'd let anyone else know of the troubles I ran into with my F18A installation.

 

First and foremost; this is an absolutely awesome piece of hardware, but then I knew that when I bought it.  If you don't have one, you should!

 

---------------

 

Anyhow, I started the project, oh about 3-4 years ago, and unfortunately, it never seemed to work right from day one, for me.  It was very intermittent.  Sometimes it would work, sometimes it wouldn't.  And when I say it wouldn't, I mean the console wouldn't turn on, zero video, zero sound, zero anything but a power light on the TI power supply.

 

I'd wiggle the cable, turn it off, turn it on, sometimes it would come back, other times it wouldn't.  I tried different monitors, different video cables, I even changed out the VGA ribbon cable (internal one), to no avail.

 

I tested it with the bare motherboard on the desk, and it would work.  Soon as I put it in the TI case, it would flake out again.  I did use the original RF shield, and really wanted that in there. I checked for shorts to see if it was hitting the F18A, but there was plenty of clearance.  I tried just about everything, and figured it was a faulty TI socket, gave up, and let it sit for a couple years (sad I know).

 

However, since I had the burning desire to get that thing working, I sat down yesterday and fiddled with it until I finally found the problem!

 

The stupid VGA ribbon connector was shorting out on the RF shield!  Both of my VGA ribbon connectors (two completely different brands) both exhibited the same problem.  Let me repeat that, the ribbon cable, not the F18A was shorting out.  Certainly wasn't my first thought, or tenth...

 

Hopefully, this will help someone else cut down a couple years of wasted non-enjoyment, out of the awesome F18A. ;-)

 

Here was my final solution, and it hasn't flaked out since! (double yay)

 

Attached Files



#2 Lee Stewart OFFLINE  

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Posted Sun Jan 7, 2018 10:41 AM

You have probably noticed over the years that I am a bit(?) OC.  Re the last picture with black tape, is that on top of the blue tape of the previous pictures?

 

...lee



#3 CantStopClicking OFFLINE  

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Posted Sun Jan 7, 2018 11:04 AM

You have probably noticed over the years that I am a bit(?) OC.  Re the last picture with black tape, is that on top of the blue tape of the previous pictures?

 

...lee

 

The blue tape was my experimenting.  I taped over each section, until I found the actual failing/shorting part.  Plus I figured it would stand out better in the photo.

 

It was then replaced with black electrical tape, as I didn't trust the insulating properties of masking tape.

 

I never really suspected that to be the problem, because the wires inside the ribbon were below the insulation (visually).  But, apparently when the shield got put in - and specifically - the metal side clamps, it would press the ribbon cable tight and push the wires out, *just* enough to short on the shield, sometimes.  Drove me nuts, about 2hrs of tearing it down and putting it back together (fully mind you), and firing it up each time.  Ugh...

 

Cheers!

 

-Dano


Edited by CantStopClicking, Sun Jan 7, 2018 11:05 AM.


#4 towmater OFFLINE  

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Posted Sun Jan 7, 2018 12:11 PM

Makes sense. But why did you insist on keeping the RF shield?



#5 CantStopClicking OFFLINE  

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Posted Sun Jan 7, 2018 12:22 PM

Makes sense. But why did you insist on keeping the RF shield?

 

Uh.... RF?

 

I have a lot of sensitive electronic test equipment, don't need any extra RF floating around. (that's a losing battle, I know)

 

But mostly, I'm OCD and because I could!  Lol



#6 towmater OFFLINE  

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Posted Sun Jan 7, 2018 12:25 PM

 

Uh.... RF?

 

I see, I didn't realize the off switch on the TI was broken.  :grin:



#7 CantStopClicking OFFLINE  

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Posted Sun Jan 7, 2018 12:41 PM

I see, I didn't realize the off switch on the TI was broken.  :grin:

 

hehe

 

Off, what?  I don't use it!

 

Short, funny, related story;

 

When I first got my TI in '82, I had nothing but the console and the manuals, no cassette, no cartridges. I typed in every single program in the TI-BASIC manual to learn, as such, I had no way to save my programs, so I just would leave the TI on.  Once my dad found out I was doing that, he banned me from the computer (wasting electricity).  I promptly went out and collected my paper-route money and bought a cassette recorder, only to find-out you really can't use a "regular" tape recorder.  Luckily, the lady at K-Mart was super nice, and she let me exchange the recorder for a DATA recorder (twice the price) for nothing.  I don't know what happened to her (she was the smartest lady I knew then), but she kept me going on the TI for the next year or so, giving me tips to when stuff was going on sale or getting marked down so I could afford it.  I was about 12 at the time, so I really appreciated it.  A month's paper-route only allowed me to get one cartridge a month, and I did!  It was a constant battle for TI time because I had to use the only TV in the house for it, dad wasn't thrilled, but I persisted!

 

Cheers!



#8 Lee Stewart OFFLINE  

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Posted Sun Jan 7, 2018 3:27 PM

Makes sense. But why did you insist on keeping the RF shield?

 

It doubles as a heat sink—though, with the 9918A removed, it probably is not nearly so useful in that capacity.

 

...lee



#9 Tursi OFFLINE  

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Posted Sun Jan 7, 2018 6:28 PM

Here was my final solution, and it hasn't flaked out since! (double yay)


Dude, I don't think I'd have thought of that either! Thanks for posting!

#10 matthew180 OFFLINE  

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Posted Sun Jan 7, 2018 7:42 PM

I hate that connector!  It is the single biggest headache about the F18A design, i.e. getting the VGA signals off the board in into a header of some sort.  I don't know if anyone ever reported that particular problem before, so I'm glad you got it sorted out and posted the solution!  Make sure you update your F18A firmware if you want to run the latest software design for the F18A.



#11 CantStopClicking OFFLINE  

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Posted Tue Jan 9, 2018 1:21 AM

Dude, I don't think I'd have thought of that either! Thanks for posting!

 

I was surprised to say the least...

 

I hate that connector!  It is the single biggest headache about the F18A design, i.e. getting the VGA signals off the board in into a header of some sort.  I don't know if anyone ever reported that particular problem before, so I'm glad you got it sorted out and posted the solution!  Make sure you update your F18A firmware if you want to run the latest software design for the F18A.

 

I did a quick search of the threads to see if anyone else had similar issue, but didn't see anything (I only looked quickly).  So, I figured it would be a good thing to document.  Most people probably remove the RF shield, so it wouldn't likely be a problem for those.  But, me and my OCD, had to get that back to looking original, all tucked away.  There didn't seem to be any reason why it shouldn't go back in there just fine.  Had to figure it out.

 

So far, it's still working and hasn't glitched once!  Now, just need to update it.

 

Cheers!

 

-Dano






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