Jump to content
IGNORED

TI99-4 (Non A) - Hitting dead end on troubleshooting


Recommended Posts

4 hours ago, UsagiElectric said:

Oh, and this was the cause of the failure!
No clue how that piece of solder got there, it's up under the edge of an original TI socket in an area where I didn't do any rework, so could have been from me or could have been previous owner stuff. Either way, it's free and clear and alls good now!

IMG_0077.JPG

That is awesome.  A simple solder bridge hidden from view.  An incredible failure mode.  Putting this much work into reviving this gal.  Hats off to you.

 

It does look interesting.  Not sure if that is a factory socket, but it has the TI logo on it so I would be happy to assume it is factory.  That solder blob looks end-user, but who really knows.

  • Like 2
Link to comment
Share on other sites

On 5/30/2023 at 3:41 PM, UsagiElectric said:

Oh, and this was the cause of the failure!
No clue how that piece of solder got there, it's up under the edge of an original TI socket in an area where I didn't do any rework, so could have been from me or could have been previous owner stuff. Either way, it's free and clear and alls good now!

 

Don't you just love those non-tented vias on the TI motherboards... Traces that run between pads also do not have solder mask, and makes it really easy to create this problem.  I had a similar fault with a wisp of solder that was too small to see without magnification (0.002in / 0.05mm wide).  In my case it was self imposed, and a happened when I removed the DRAM from the 4A motherboard, and later affected my testing of the F18A MK2.  It took me a long time to find the problem.

 

Nice work, persistence pays off!

 

VBB_to_CAS_short.jpg

  • Like 4
Link to comment
Share on other sites

On 5/30/2023 at 3:37 PM, UsagiElectric said:

Awesome, thanks!

Ah, that makes sense! I was getting confused on order of things occurring here, but I'm following now!

You get all the credit my man! Seriously, I don't think this thing would have come back to life without your help!

That did the trick, keyboard works perfectly now, and isn't quite as terrible to use as before. It's a bit like typing on a teletype, but I think with some practice and retraining of the brain, you could get fairly quick at it.

I manged to get it a little better, but there's still a ridiculous amount of noise/interference, and it makes it straining to look at, so something is definitely funky in the video circuitry, but that's a problem for future me.

IMG_20230530_121358097.jpg

And you have three of the five sidecar boxes and a Thermal Printer connected to it too! Nice! Are the four big cartridge boxes for the Scholastic Spelling cartridges, or are they something else entirely?

Link to comment
Share on other sites

On 5/30/2023 at 3:26 PM, humeur said:

Bravo

Thanks!

On 5/30/2023 at 4:38 PM, Tursi said:

Nice! It does look like a splash, doesn't it? Just a tiny thing like that, it's like the third time someone has posted a picture like that (that I've seen at least!)

Thanks! Definitely not that way from the factory, and very well could have been from me at some point in all my rework. The fact that it was under a TI socket though gives me a bit of pause. Maybe from a previous owner? Either way, problem solved!

 

On 5/30/2023 at 5:03 PM, acadiel said:

I had to replace my video crystal on my /4.  The picture looked horrible - kind of like what you posted.  I barely had color.  Maybe that?

Oooh, interesting idea. I did check the oscillator frequency at the chip and its bang on though, so it might be a little deeper in the analog stuff.

Link to comment
Share on other sites

1 minute ago, UsagiElectric said:

Thanks!

Thanks! Definitely not that way from the factory, and very well could have been from me at some point in all my rework. The fact that it was under a TI socket though gives me a bit of pause. Maybe from a previous owner? Either way, problem solved!

 

Oooh, interesting idea. I did check the oscillator frequency at the chip and its bang on though, so it might be a little deeper in the analog stuff.

Mine appeared to be oscillating, but yeah, replacing it was the only thing that fixed it.  These old systems are sometimes conundrums!  Great job sniffing out that trace!  
 

That’s why I love this place - we have the hardware level engineers that can disassemble and trace assembly all the way to the folks like me that are a little bit higher level and contribute in our own way.    This is an amazing community!

 

Thanks for dropping by and trusting us to help you out!  It sometimes does take a second, third, or more set of eyes to find something.  There’s several jokes about the TI that date back to Faires and such that, in essence, “if something’s not wrong, it will happen - just wait”.  (This especially is true of demos at CTIUG, as Hal can attest!). 😂 

  • Like 1
Link to comment
Share on other sites

On 5/30/2023 at 7:35 PM, OLD CS1 said:

That is awesome.  A simple solder bridge hidden from view.  An incredible failure mode.  Putting this much work into reviving this gal.  Hats off to you.

Thank you!
It's definitely a factory TI socket, both the 99/4 motherboards I've seen have the same sockets on the Console Roms, but it still could have come from me or a previous owner. Either way, it was an absolute bear to hunt down, but we got there in the end!

 

15 hours ago, matthew180 said:

Don't you just love those non-tented vias on the TI motherboards... Traces that run between pads also do not have solder mask, and makes it really easy to create this problem.

Whoa, that's an insane solder bridge! I'm not sure I'd have been able to find that one, it definitely would have had me running circles for a long time.

 

10 hours ago, Ksarul said:

And you have three of the five sidecar boxes and a Thermal Printer connected to it too! Nice! Are the four big cartridge boxes for the Scholastic Spelling cartridges, or are they something else entirely?

Oh yeah, going for the big TI train!
Current loadout from left to right is TI Color Monitor, 99/4, Speech Syntehsizer, Thermal Printer, RS-232, Phone Modem, Memory Expansion, Disk Controller and Disk Drive. Would love to expand it with a 2nd Disk Drive and the Video Controller and P-Code sidecars someday. The Video Controller is rare but they did actually produce them, so I'm keeping an eye out for it. The P-Code sidecar was only a prototype, so I think I'll have to get a P-Code PEB card and modify it to go into a spare box to make a replica P-Code sidecar.

The software is nothing fancy, just Multiplan and TI-Writer in the binders, and Personal Record Keeping, Tax/Investment Record Keeping, Terminal Emulator II and Mini Memory. And I think I have Extended Basic in a cartridge around here somewhere too. I have a weird obsession with productivity/office software, haha.

IMG_20230601_100231258.jpg

IMG_20230601_100304414.jpg

  • Like 4
Link to comment
Share on other sites

4 hours ago, UsagiElectric said:

Thank you!
It's definitely a factory TI socket, both the 99/4 motherboards I've seen have the same sockets on the Console Roms, but it still could have come from me or a previous owner. Either way, it was an absolute bear to hunt down, but we got there in the end!

 

Whoa, that's an insane solder bridge! I'm not sure I'd have been able to find that one, it definitely would have had me running circles for a long time.

 

Oh yeah, going for the big TI train!
Current loadout from left to right is TI Color Monitor, 99/4, Speech Syntehsizer, Thermal Printer, RS-232, Phone Modem, Memory Expansion, Disk Controller and Disk Drive. Would love to expand it with a 2nd Disk Drive and the Video Controller and P-Code sidecars someday. The Video Controller is rare but they did actually produce them, so I'm keeping an eye out for it. The P-Code sidecar was only a prototype, so I think I'll have to get a P-Code PEB card and modify it to go into a spare box to make a replica P-Code sidecar.

The software is nothing fancy, just Multiplan and TI-Writer in the binders, and Personal Record Keeping, Tax/Investment Record Keeping, Terminal Emulator II and Mini Memory. And I think I have Extended Basic in a cartridge around here somewhere too. I have a weird obsession with productivity/office software, haha.

IMG_20230601_100231258.jpg

IMG_20230601_100304414.jpg

I love this sidecar train!  I have everything you do - and again, no P-Code nor Video controller, but I should set this thing up on a table at VCF-SE!

  • Like 1
Link to comment
Share on other sites

1 hour ago, acadiel said:

I love this sidecar train!  I have everything you do - and again, no P-Code nor Video controller, but I should set this thing up on a table at VCF-SE!

Gotta steal room from all the phone stuff!

  • Like 2
Link to comment
Share on other sites

On 6/1/2023 at 11:06 AM, UsagiElectric said:

Oh yeah, going for the big TI train!

Current loadout from left to right is TI Color Monitor, 99/4, Speech Syntehsizer, Thermal Printer, RS-232, Phone Modem, Memory Expansion, Disk Controller and Disk Drive. Would love to expand it with a 2nd Disk Drive and the Video Controller and P-Code sidecars someday. The Video Controller is rare but they did actually produce them, so I'm keeping an eye out for it. The P-Code sidecar was only a prototype, so I think I'll have to get a P-Code PEB card and modify it to go into a spare box to make a replica P-Code sidecar.

 

The p-Code sidecars were actually sold for a year or so, but most of them went to educational users--and straight to the landfill once they reached end-of-life. TI mentioned in one of their newsletters that the only reason they did go into production was to fulfill their contractual requirements while finalizing the PEB version--with the goal to stop making them as soon as the PEB card was available. There are at least four of them in the wild, counting mine and those I have seen evidence of over the years. Mine is actually complete in original production packaging.

 

There are 15-20 of the Video Controller sidecars floating around in the community, so they are actually an attainable goal if you wait/look long enough.

  • Like 2
Link to comment
Share on other sites

On 6/1/2023 at 2:35 PM, acadiel said:

I love this sidecar train!  I have everything you do - and again, no P-Code nor Video controller, but I should set this thing up on a table at VCF-SE!

Oh awesome! Looking forward to seeing the setup soon!

On 6/2/2023 at 10:33 AM, Ksarul said:

The p-Code sidecars were actually sold for a year or so

Interesting, I was always under the impression that the four or so out there were prototypes. Color me all the shades of jealous that you actually have one! My goal is to build a replica P-Code sidecar using a spare RS-232 box and a P-Code PEB card. But both the P-Code and Video Controller are just going to be all about playing the long game. We'll get there eventually!

  • Like 2
Link to comment
Share on other sites

Not a TI guy myself (though I do think they're nifty machines), but I've been subscribed to the Usagi Electric channel for some time and have been following this with interest.  Really glad to see this machine up and running again - anytime a rare and/or unusual machine is resurrected is a good thing in my book.  Kudos to everyone involved!

  • Like 5
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...