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Greasy cartridge port?


ralphb
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I always wondered ... When I plug in a pristine cartridge board into the TI 99, and then remove it, the connectors on the cart feel greasy or oily.

 

Is this just gunk, or is the cartridge port "greased" to make insertion of carts easier? How would that even work?

 

If the "grease" is insulating, wouldn't that prevent the cart from connecting to the bus? And if it is conducting, well, wouldn't that short everything?

 

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This was a common problem back in the day. The culprit is a little self-destructing sponge like item in the GROM port connector that was originally designed to 'clean' the cartridges. What it actually does is collect a bunch of crap and deposit it all over your clean cartridges.

 

1) What you want to do is open up the TI, remove the GROM connector (it just slides out like a cartridge).

2) Look at the face and notice the little tabs that hold it onto the connector, remove the face cap and throw it away.

3) Now drop the entire connector in cup of water mixed with a generous amount of DawnTM diswashing detergent.

4) Let it sit for a couple of hours.

5) Remove it from the detergent, and rinse thoroughly.

6) Dry the GROM port completely, compressed air is best, or a hair dryer will work.

7) Re-install and NEVER have to worry about it again.

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The felt pad that was in there was a metal-shavings magnet. The oil collected the metal, the metal spread far enough through the pad to short out the contacts, and cartridges started responding strangely. Remove the felt and the problems go away. . .

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Funny you should raise this topic.
I have mentioned before that I am a TI noob (only got my first 99 this year) and have no historic background with them.

So was not aware of any peculiarities with the cartridge port.

But during my FlashROM testing I was finding the cart edge connector was getting sticky with a black, grease like substance.

Actually it was amazing how much I was wiping off the connectors after each insert.

I have not stripped the TI down yet, so I'm thinking years of accumulation.

I did manage to give the connector in the computer a clean using a bit of cardboard (seen this method used before) and this solved some of the intermittent issues I was getting.

I also have some very old Strowger microscrub strips (very old telephone exchange equipment contact cleaner) that I used to clean the connector contacts in the computer.

These are very handy if you can get your hands on them...probably have not been made in decades...only one reference I could find online.

 

http://www.worthpoint.com/worthopedia/strowger-microscrub-contact-cleaning-220699437

 

 

Cheers,

Shane

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Funny you should raise this topic.

I have mentioned before that I am a TI noob (only got my first 99 this year) and have no historic background with them.

 

Hi Shane,

Many of us old TI'ers have had this done to our computers for years, and it's one of the first things that returning TI'ers do to their consoles, so we don't really think much about it. Since you are a self-described newbie, I refer you to << THIS >> excellent article on the Mainbyte site.

 

Welcome aboard! :thumbsup:

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Thanks for the link, that is good info. :)
Did not realize there was the felt behind that black 'cap / cover'.

And the cardboard cleaning that I did is the same as what was mentioned in the very last bit of that link (Seen that same method with other cartridge based devices) :thumbsup:

Although, I did the clean with everything still in place so it looks like I will need to have a bit of a teardown to remove that cover with the felt then.

 

Thanks,

Shane

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I've worked at cleaning my cartridge ports significantly, all of the gunk is out.

 

But it seems they oxidize quickly... Seems like I have to recondition them weekly... I've been wishing I could find a gold plated replacement connector... Anyone have any solutions for this? I'm tempted to try Deoxit.

 

-M@

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Ahh, looks like my TI teardown is going to happen quicker than anticipated.

My only working TI has had a failure before my eye's while using it today.

Had been using it on and of for a couple of hours when I performed a soft reset back to the TI screen

only to be confronted with this...

 

Assuming VRAM...

post-37708-0-97445200-1468671837_thumb.jpg

post-37708-0-43920600-1468671845_thumb.jpg

post-37708-0-44425000-1468671850_thumb.jpg

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That's awesome, thanks mizapf.

 

I found a random VRAM picture, and assuming this would indicate my faulty VRAM chip is the 3rd chip in from the left

while looking at the board in the same orientation as it sits in the computer (not looking from the rear of the computer).

 

Thanks again for the link...really cool.

 

Cheers,

Shane

post-37708-0-80489300-1468720987_thumb.jpg

Edited by 00WReX
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It's not that simple according to the schematics. The chips in your picture (from left to right) are U102 – U109. The bits they represent (from MSb – LSb) are as follows:

 

MSb--> U109

U107

U106 <--5th chip from the left

U105

U103

U108

U104

LSb--> U102

 

It looks like the one you want is U106.

 

...lee

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I updated the Ninerpedia page: http://www.ninerpedia.org/index.php?title=Troubleshooting

 

This should be the correct order.

 

Based on the parts placement diagram, the schematics and the fact that Shane's replacing U106 fixed his VRAM bit 2 problem, the order is not a straight right-to-left but rather as in the following image:

 

post-29677-0-75524200-1468767345_thumb.png

 

...lee

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I had another big win today...super excited to get another TI up and running.

I fixed an NTSC original TI-99/4A.

This has been dead since I received in in late April.

I don't have an oscilloscope, only a logic probe and Multi-meter so I sort of narrowed it down, but did end up socketing the ROMS and SRAMS and a couple of others...

Found one of the SRAMs to be dead.

So now I have a Beige PAL machine (working after replacing a dead VRAM last weekend), and now an original style NTSC machine.

 

What I did with this one, was to remove the felt from behind the cap, and then re-fit the cap.

I thought the cap may help (slightly) to support the bare FlashROM...

 

Cheers,

Shane

post-37708-0-33672900-1469360887_thumb.jpg

post-37708-0-43423900-1469360896_thumb.jpg

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  • 3 months later...

Is it ok to use denatured alcohol (methylated spirits overseas) to perform the cleaning of the cartridge contacts and the port? It seems to be getting more challenging finding tape head cleaner these days. Perhaps something like this: <Link> ? As I've been testing and cleaning I noticed my carts with upper contacts are all flaky, I can't think of it being anything than needing a good cleaning.

 

Thanks.

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Is it ok to use denatured alcohol (methylated spirits overseas) to perform the cleaning of the cartridge contacts and the port? It seems to be getting more challenging finding tape head cleaner these days. Perhaps something like this: <Link> ? As I've been testing and cleaning I noticed my carts with upper contacts are all flaky, I can't think of it being anything than needing a good cleaning.

 

Thanks.

Yes, I don't see any issue with it, you can get this at almost any building supply and, I believe, Walmart. I use 91% alcohol from Walmart or a local drugstore for most of my cleaning on circuit boards. Just did this on a Macbook Air that I just repaired.

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  • 8 months later...

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