F18A keeps coming unseated

[nuxi]

I'm finally getting around to installing my F18A, but the slightest bit of torsion seems to pop it out of the socket. I've now dis- and re-assembled the thing four times. A quick search doesn't seem to show this is a persistent problem, but I thought I'd ask anyway: do I bother trying a different motherboard? Or do I need to go to the trouble of replacing the socket with a machined one?

[Hans23]

You could try inserting a machined socket into the TMS9918A socket and put the F18A into that.  Machined sockets have slightly thicker pins and are often longer than the pins of the F18A, so that might help.

[Gary from OPA]

this was a problem with my TIM as well, the 9918 socket is cheap, it has a habit of getting loose. -- you could try doing a wedge between the top of the board and the ti99 plastic case itself, using a non-conductive hard rubber that has a bit of squeeze but not too much to keep it tight. - or if you have a good way to desocket the existing socket on the motherboard and replacing it that might be the best, but with age of ti99, you need to be careful as the traces on the pads have are easy to damage when desoldering

[nuxi]

15 minutes ago, Hans23 said:

You could try inserting a machined socket into the TMS9918A socket and put the F18A into that.  Machined sockets have slightly thicker pins and are often longer than the pins of the F18A, so that might help.

Ok, that's not a bad idea ... and it would also seat all the pins in the main socket, not just the few that the F18A uses. I wonder if a DIP socket or two single rows would work better.

[nuxi]

19 minutes ago, Gary from OPA said:

this was a problem with my TIM as well, the 9918 socket is cheap, it has a habit of getting loose. -- you could try doing a wedge between the top of the board and the ti99 plastic case itself, using a non-conductive hard rubber that has a bit of squeeze but not too much to keep it tight. - or if you have a good way to desocket the existing socket on the motherboard and replacing it that might be the best, but with age of ti99, you need to be careful as the traces on the pads have are easy to damage when desoldering

I mean, I have plenty of other consoles I could try. The question is, is this going to be a Cinderella-like effort to find the perfect fit? Or are most of them good enough, and I just got unlucky?

[Shift838]

9 hours ago, nuxi said:

I'm finally getting around to installing my F18A, but the slightest bit of torsion seems to pop it out of the socket. I've now dis- and re-assembled the thing four times. A quick search doesn't seem to show this is a persistent problem, but I thought I'd ask anyway: do I bother trying a different motherboard? Or do I need to go to the trouble of replacing the socket with a machined one?

if your F18A has normal pins and not tall, which is the case for most for the TI-99 then using a machine socket will not work.  This is because the diameter of the normal pins is much smaller than want a machine socket calls for and will not make a proper connection.  Your dualwipe socket on the TI could need replaced with a new one if any of the contacts have lost their springy-ness (can't think of the right word).

 

 

 

[+OLD CS1]

8 hours ago, nuxi said:

I mean, I have plenty of other consoles I could try. The question is, is this going to be a Cinderella-like effort to find the perfect fit? Or are most of them good enough, and I just got unlucky?

I have two F18A-enhanced consoles.  Other than one becoming unseated during transit to Chicago via airport baggage handling, neither have been a problem.  Have you tried a nail gun?

[RickyDean]

9 hours ago, nuxi said:

I'm finally getting around to installing my F18A, but the slightest bit of torsion seems to pop it out of the socket. I've now dis- and re-assembled the thing four times. A quick search doesn't seem to show this is a persistent problem, but I thought I'd ask anyway: do I bother trying a different motherboard? Or do I need to go to the trouble of replacing the socket with a machined one?

What @Shift838 said applies, but you can also have headers on the F18A that are too big in diameter to plug into a machine socket too. The tension or clamping force that holds a pin in the socket can deteriorate especially after there are a multitude of removals and insertions. For the socket holding the TI VDP, if you have reasonable soldering skills, cut out the old socket with electrical cutting dikes, then desolder each pin separately, using a desoldering bulb or gun, then solder in a quality dual wipe socket, check continuity after each solder joint, then you should be well on your way to a solid experience. 

You can also try a plastic wire tie to keep it retained if you don't want to go through all that trouble. place it under the socket the length of the F18A and cinch it down.

Edited March 7 by RickyDean
added content

[nuxi]

9 hours ago, Hans23 said:

You could try inserting a machined socket into the TMS9918A socket and put the F18A into that.  Machined sockets have slightly thicker pins and are often longer than the pins of the F18A, so that might help.

This seems to have worked! Thanks everybody for the suggestions.

[HOME AUTOMATION]

Springiness...♨️

 

@Shift838 

[Gary from OPA]

Yes, plastic wire ties work as well. That was a good solution for the TIM as well.

[matthew180]

@nuxi  Do you have an original F18A (wider than the socket), or are you taking about the newer MK1?  I do not have a lot of reports of the F18A coming out of the socket that easily, but it seems you found a solution that is working.  Any chance you took a photo or two?

 

[nuxi]

1 hour ago, matthew180 said:

@nuxi  Do you have an original F18A (wider than the socket), or are you taking about the newer MK1?  I do not have a lot of reports of the F18A coming out of the socket that easily, but it seems you found a solution that is working.  Any chance you took a photo or two?

 

It's the batch from last year, so presumably the MK1. I didn't take a picture, but I'd be happy to if it helps. It really just looks like two sockets stuck together.

[matthew180]

If you do not have one of these two boards, then you do not have an F18A.  If that is the case, I would really appreciate it if you could change the thread title to not say "F18A".

 

[RickyDean]

48 minutes ago, nuxi said:

It's the batch from last year, so presumably the MK1. I didn't take a picture, but I'd be happy to if it helps. It really just looks like two sockets stuck together.

Is that the Tang 9k? instead of a F18A?

[nuxi]

It's the one on the left. From the batch in January last year.

 

Oh, I get it, no the sockets themselves look like two sockets stuck together , so I was saying a pic wouldn't really help.

Edited March 7 by nuxi

[matthew180]

37 minutes ago, nuxi said:

It's the one on the left. From the batch in January last year.

 

The one on the left is the original F18A and I have not made those since about 2017, so unless you bought a used one from someone, then you do not have an original F18A.

 

The one on the right is the F18A-MK1, and I started making those in 2022, IIRC.

 

What you see above are the ONLY variations of the F18A, and there are no other boards or sockets involved.

 

Please recheck what you have.  As RickyDean mentioned, you probably have the Tang 9K, which is not the F18A (and why I would appreciate it if you could edit the thread topic to say Tang 9K, rather than F18A).

 

Ah, right, I forgot, Hans23 did make a few batches of the original F18A.  I do not know what PCB pins were used for those units, so if putting a machine socket into the 99/4A VDP socket is working for you, then great.

 

Edited March 8 by matthew180
Corrections

[nuxi]

This was the shift838 run