Help with broken? TI-99/4A ?

[+arcadeshopper]

composite

 

vga

[walterg74]

Two options:

1: remove chips from motherboard, install sockets, replace with new chips

2: buy f18a, remove 9918a chip, clean off goo and remove heat block from rf shielding, install f18a in vdp socket, run vga cable to vga monitor, dance the happy dance

 

f18a source: http://codehackcreate.com/store#!/F18A-V1-7-Video-Board/p/14022176/category=0

 

Greg

Ouch.. Yeah I don't think I want to spend ~80 bucks on that...

 

If anything it would have to be the vdp change, but putting assi how easy or difficult it would be for me for the soldering, I can't even find one listing for them on ebay...

 

I think I might have to deal with the seller on this one and try to get a refund, as it was listed as working.

[+arcadeshopper]

how much did you pay for it?

 

Greg

[walterg74]

$50 + $25 shipping (came with plentry of cartridges)

[+arcadeshopper]

$50 + $25 shipping (came with plentry of cartridges)

 

Sounds like you got a deal carts are worth something depending on the titles... I would suggest instead of doing that that you send it to someone here who's willing to do the repair or swap the motherboard with a working one..

 

Greg

[matthew180]

Ouch.. Yeah I don't think I want to spend ~80 bucks on that...

I sell them as cheap as I can. The demand is very low (less than 100 a *year*), so production costs are higher. Sorry. This is hobby quantity hardware and I have to hand finish the assembly on each one, so it will always cost more.

 

If anything it would have to be the vdp change, but putting assi how easy or difficult it would be for me for the soldering, I can't even find one listing for them on ebay...

Why does it matter if I don't sell them on ebay (you have mentioned this twice)? I have a small store on my website and support the F18A primarily through this forum where the bulk of 99/4A users hang out. The F18A is not something made by many companies or some cheap board coming out of China. It is a hobby project that turned into a hobby product.

 

The F18A is an easy install on the 99/4A because the original VDP is already in a socket. You only have to pop out the original 9918A VDP (i.e. it only takes a screw driver and a little patience) and insert the F18A. The hardest part is probably modding the console for the VGA connector. Removing the DRAM chips is a lot harder, especially on the old motherboards. But this depends on each person's own soldering skills.

 

I think I might have to deal with the seller on this one and try to get a refund, as it was listed as working.

These are old systems and they won't last forever. We are seeing that the DRAM chips are usually the first to fail. If you have an F18A, the DRAM chips in the system are no longer used (the F18A has its own VRAM), so it does not matter if they are failing (you can even remove them completely for some power savings if you want.)

 

You might want to see if Marc Hull still has some consoles for sale, that way you know you will be getting a unit that has been checked out and upgraded.

[walterg74]

I sell them as cheap as I can. The demand is very low (less than 100 a *year*), so production costs are higher. Sorry. This is hobby quantity hardware and I have to hand finish the assembly on each one, so it will always cost more.

I'm not judging your price, it is what it is and it's probably fair. It's just not an amount that *I'm* willing to spend on for what it does.

 

 

Why does it matter if I don't sell them on ebay (you have mentioned this twice)? I have a small store on my website and support the F18A primarily through this forum where the bulk of 99/4A users hang out. The F18A is not something made by many companies or some cheap board coming out of China. It is a hobby project that turned into a hobby product.

The F18A is an easy install on the 99/4A because the original VDP is already in a socket. You only have to pop out the original 9918A VDP (i.e. it only takes a screw driver and a little patience) and insert the F18A. The hardest part is probably modding the console for the VGA connector. Removing the DRAM chips is a lot harder, especially on the old motherboards. But this depends on each person's own soldering skills.

 

I think you are misreading my comments. What I'm "complaining" about not finding on ebay are replacement video ram chips, not yours....

 

These are old systems and they won't last forever. We are seeing that the DRAM chips are usually the first to fail. If you have an F18A, the DRAM chips in the system are no longer used (the F18A has its own VRAM), so it does not matter if they are failing (you can even remove them completely for some power savings if you want.)

 

You might want to see if Marc Hull still has some consoles for sale, that way you know you will be getting a unit that has been checked out and upgraded.

Thanks for the tips, I will keep them in mind.

 

Does anyone know or can explain if these chips are bad, how come when I put a cartridge in it seems to work fine? Are they not related at all for anything?

 

What would this failure I have cause besides seeing these characters on the screen in basic ?

Edited February 5, 2016 by walterg74

[+Ksarul]

You have a RAM chip with a few stuck bits. You probably have some errors on screen with the games you play, but they may be hidden in the graphics/less visible when using the cartridges. They may even be not visible at all, depending on where the cartridge places the screen data in the VDP memory. The problem is likely in a single chip--and only affects bits at a few positions (as opposed to the whole chip being bad). It may also extend into other areas outside the standard screen display (BASIC programs are also stored in VDP memory, as are data files for Adventure or Tunnels of Doom), which would corrupt that data. Your only real choices are to replace the bad chip or to put an F18A into the console, assuming you want to fix it (or use it for anything except cartridge games).

[+arcadeshopper]

http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.TRS0&_nkw=16k+dram&_sacat=0

 

I dunno maybe the ebay issue is you don't know what you are looking for? It's a chicken and egg issue. Nobody sells a "fix a TI" kit because frankly most people dispose of the console if it has any issue since they were about $10 each to replace them for the longest time. The Console is the cheap part. I paid 50$ for a nib one on ebay this week. And that was ONLY because its nib.. But frankly it may have issues coming out of the box, as it's been sitting there for 30 years+- bit being used. electronics hate that..

 

If you want to ship me your console I'll swap the motherboard with a working one for $10+shipping back.. lmk

 

Greg

[matthew180]

I'm not judging your price, it is what it is and it's probably fair. It's just not an amount that *I'm* willing to spend on for what it does.

Thanks, and sorry. The F18A gets compared to things like the RaspberryPi and Arduino when it comes to price. I try to just be factual, but it can come across harsh.

 

I think you are misreading my comments. What I'm "complaining" about not finding on ebay are replacement video ram chips, not yours....

Ah, yes, I did read it wrong. Sorry.

 

Does anyone know or can explain if these chips are bad, how come when I put a cartridge in it seems to work fine? Are they not related at all for anything?

Depending on how the DRAM is failing, only certain addresses of the memory may be bad. If a cartridge does not use much VRAM other than displaying basic tiles, then it may not expose the bad part of the memory.

 

What would this failure I have cause besides seeing these characters on the screen in basic ?

Aside from the display errors, BASIC and Extended BASIC store their programs in VRAM, so you can expect almost any BASIC/XB program to be corrupt and not run correctly. Also, disk buffers are stored in VRAM, so any reading or writing to disk might be corrupt. Any program that uses VRAM to store data could malfunction.

 

You might want to check coin-op arcade part sites for the DRAMs, many computers in the arcade machines used those DRAMs.

[walterg74]

http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.TRS0&_nkw=16k+dram&_sacat=0

 

I dunno maybe the ebay issue is you don't know what you are looking for? It's a chicken and egg issue. Nobody sells a "fix a TI" kit because frankly most people dispose of the console if it has any issue since they were about $10 each to replace them for the longest time. The Console is the cheap part. I paid 50$ for a nib one on ebay this week. And that was ONLY because its nib.. But frankly it may have issues coming out of the box, as it's been sitting there for 30 years+- bit being used. electronics hate that..

 

If you want to ship me your console I'll swap the motherboard with a working one for $10+shipping back.. lmk

 

Greg

Yes, that may very well be it! All I could search for was for ti 99 ram, etc, so probably something more specific I don't know how to search.

I really appreciate your offer, problem is I'm not from the US, so I buy these thing whenever I get a trip over there, which means I'm just there for a week or two and then I'm gone until who knows when the next one is.

 

Just by luck I returned home this past sunday and now I get to go again on March 1st, so may be second chance to get a really working one, amd see what I do woth that one that I left at a friend's house.

[+Ksarul]

Here is a link to the necessary 4116 RAM chips on eBay. They are pretty easy to find--once you know what you need (and where the problem is on the board). I hope this helps!

[walterg74]

Here is a link to the necessary 4116 RAM chips on eBay. They are pretty easy to find--once you know what you need (and where the problem is on the board). I hope this helps!

Thanks for that!

 

So any found there as long as they say 4116 ram, and working should be god?

 

did I need 8 chips?

[+arcadeshopper]

Thanks for that!

 

So any found there as long as they say 4116 ram, and working should be god?

 

did I need 8 chips?

 

yes you need 8 chips to replace them all, and 8 sockets so you can replace them easier in the future if necessary

[walterg74]

Hey folks. Sadly my trip to the US (which starts today) is only for a few days, and could't get to take look and order these in time.

 

As such, and since the seller refunded the cost of the item anyway, and I already got another TI when he did, I will go ahead and give the TI away to anyone that wants it and is willing to pay shipping.

 

Just PM me and create a shipping label? (If fedex better, I have a fedex store across from my hotel if not I'll look for a ups drop off?).

 

Should be from my location 77380, to yours, and I'll paste it o. The box and get it out to you this week.

 

Cheers!