TheRealAnubis

June 14, 2014

Great suggestions! I may even have a couple of those games!

A PE box and drives plus XB adds a whole 'nother layer to it. When I got mine, the TI became to me a "real computer" I could actually do stuff with. Why aren't you considering that option? Lack of funds, the space to set it up, no desire to go that route?

I guess a little of each. I've not laid eyes on an entire system, or even the PEB for that matter. There are a few drives available on ebay, and they look HUGE to me, like the old MFM drive that was in my 286. I've been kicking around the HXC floppy emulator, but I've not seen how they hook that up to a TI... I just haven't had time to research it far enough, and it's a little pricey for me at this point. It's the same situation with the Atari 800XL - I'll likely just play cartridge games on it because the drives are selling for $40+ including shipping, and they are listed as 'untested, no cables, power supply, etc.' For me 'untested' means broken. Even most of the 'working' stuff ends up broken somehow!

Have you tried any of the several excellent TI emulators? All of this and lots more is available to see what you like enough to get the real versions.

That's a good idea! I never seem to remember the emulators, and I've used quite a few of them.. I'll see what I can get going in that department! Thanks!

What brought you to the TI? You seem to know your way around inside of one.

Long ago I had a friend that had one. Well, his parents had one. His mom used it for her accounting business, but when they weren't home we would play games on it. He also had an Intellivision that we played almost to death (AD&D Cloudy Mountain - best game going IMO).

Recently out of the blue a friend brought one to me. It was his late brother's, and no one knew anything about it or really wanted it. He knew I was into vintage stuff, so he wanted to know if I wanted it. I (of course) said I did!

Out of the box, it was not working, so I pulled it apart to see what was going on. From there I was compiling a list of problem chips and trying to locate them online. Unlike the Commodore, I didn't see a ready supply of used or NOS IC's. That could mean that it is rare for these to burn out, OR, they are just hard to find.

I tend to tear things apart and see what makes them tick - old hardware is very interesting to me. Repairing and tinkering with old systems is a fun hobby for me, and it keeps me learning all the time!

June 14, 2014

Hi,

Fail time is unknown. As far as the person that had it knew, it was working fine!

Some of this old electronic stuff is going dead on the shelf. Things like Tantalum capacitors which can fail to a dead short and electrolytics, which have multiple failure modes and can be hard to test properly. Tants are easy, just Ohm 'em. Find one dead, redo 'em all with modern good stuff, no cheap China timebombs need apply. Panasonic and Nichicon are good. Orange drops or equivalent for the Tantalums, they're polarized, btw.

Good to know - there are a number of parts and types that differ from what I'm used to working on, so those present an unknown.

Could be a power surge did it. Or a wayward connection to a port made by a child perhaps or a too inquisitive adult. I've been there many times as both a kid and an old fart. Did it look like someone had been inside before you opened it up?

Yeah, I suppose it's down to an 'anything could have happened' scenario! As far as I could tell, it looked like it had not been opened up, but depending on how careful a person was, they just could have done a nice job putting it back together. Not like the Commodore, where you can usually tell because the tabs that hold the bottom pan are soldered back poorly, or the plastic clips on the back of the top cover are broken because it wasn't reinstalled correctly.

It's either the chip(s) or where the chip feeds that causes the load. Old transistors and others have begun to grow tiny metallic "whiskers" off tinned connections inside the part. Enough stray whiskers that grow and connect to the wrong spot can short it out. NASA wrote about it, got them, too. And certain old transistor radios as well, like Zenith and others. We see more of that as time moves on and old parts grow a beard.

Now that's news to me! I would have never thought that kind of thing would happen... Hmmmmm.. So much to test!

Thank you for all of the information!

June 14, 2014

Hi,

I've seen a similar post elsewhere, but I'm not likely to get a hold of a floppy drive and box, so I'm looking for everyone's favorite cartridge games on the TI-99!

Thanks!

June 14, 2014

My General Experience with Electronic Chips is when they're Super Hot, they're Dead, ( as in A Dead Short ).. My SX, wouldn't even POST... After Removing the SID, everything worked, but the Sound and the Paddles...

I would think the TI wouldn't be any different.... Scorching Chips, are Dead Chips..

MarkO

Which then leads me to the question - what happened to this TI? The power supply is good, the power board is good, it was very clean and well taken care of, but it has several dead IC's. Strange.

June 14, 2014

Yeah, I have a whole box of NOS Mitsumis with the membrane contacts, and as far as I've seen so far, every single one I've pulled out barely responds. I haven't dismantled them to see if they can be fixed, but seems likely that oxidation is a bigger problem than on the older mechanical switches.

It's a strange setup inside.. There's a sticky plastic cover that can be gently peeled off, which I did, then I used alcohol to clean everything, and it didn't make a bit of difference..

June 13, 2014

When I Blew up the SID chip in my SX-64 in 1988, it got very hot too.. got a donor chip from a C64..

Luckly the SX was Socketed..

Yeah - I'm pretty familiar with the 64 and what runs cold, warm, and hot. Usually when they get nuclear it's a sign of a bad IC, but since I'm unfamiliar with the TI and what it does heatwise, I'm hoping someone that does a lot of repairs can give me some tips!

I'd love to find a donor motherboard for this one. I'm really interested in getting it going because it was a friend's late brother's, and apparently he loved it and was way into it back in the day. I'm hoping that I won't end up having to socket the entire board before I get it working!

June 13, 2014

Hi,

I'm on my last TI-99 to repair. This one seems to have a lot of problems. Bad keyboard, and several of the IC's are running extremely hot in under a minute.

I have already tried a different (working) VDP, and also the piggyback RAM trick (all 8 at once!)

The HOT IC's are:

SN94624N - Sound IC

SN74LS245N

TIM9904ANL

SN74LS194AN

The RAM is ice cold, and the VDP and TMS9901 heat up after a little while, but nothing extreme.

I'm concerned about these IC's that heat up to scorching almost immediately! Is anyone familiar with the IC's enough to let me know if this sounds like a batch of bad IC's?

I like to solder, but I don't really want to socket all of these IC's because once I do it's difficult to find the replacement IC's.

Thank you!

June 13, 2014

Great! One vote for tossing them!

June 13, 2014

Hi,

I'm new to the TI scene, but I've been working with (and on) Commodore computers for a long time. I know that the bottom RF shield isn't a have to re-install on them - so if someone spilled something into the console and it ended up rusting the bottom shield, you can just remove it and toss it.

The last 2 TI's that I've been working on have had serious surface rust on both parts (top & bottom) of the RF shielding. I notice that there's a ground attached to the bottom piece of the console that goes to the expansion port and then to the bottom of the RF shield. Also - the other part of the RF shield has the heatsink for the VDP.

I have some really good copper heatsinks that I can put on the VDP if necessary, and I can fix the ground to the expansion port as well.

My question is - what do you all do with these rusty shields? It can't be good to just replace them with them shedding little bits of rusty metal all over the motherboard and the insides of the case.

I took one set and wire brushed it of all surface rust, then rubbed in a light coating of sewing machine oil, then wiped that until the oil was only a light residue protecting the metal.

I've got my 'beige' unit apart now, and it's the rustiest one yet. I'm going to hold off on putting it back together until I see if anyone has a better way of dealing with them than what I've tried.

June 13, 2014

Sounds like you're on your way! Good job tracking down a wire broken inside the insulation. Rare, but it does happen. Odd you have so many dead keyboards. I always thought they were pretty sturdy, but there were cheaper ones that TI used later on.

-Ed

Yeah, overall I'm not having very good luck getting them going. The one I have working I'm pretty happy about, though!

June 13, 2014

Wouldn't it be cheaper to use a more modern parts to make a full replacement power supply? A fuse and switch (optional, many people uses power strips these day that already have switch) on primary side of a basic transformer that step down from mains to 9v AC, full wave rectifier, caps to filter out ripples after rectifier, and a 5v DC-DC converter. On the 9VAC one could build a crowbar circuit that blows fuse and shuts down the power supply if something goes wrong. With good components this could costs about the same as the saver but outlast any Commodore made C=64 power supply.

Well, in this case, I think this solution is for people that aren't willing/able to build their own power supply. I got mine because I have to test a lot of systems, and usually those systems come with classic 'bricks'. This allows the user to keep what they have, and never worry about the classic brick killing their RAM.

I also built Ray's load tester for the power supplies so I can do some testing on them as far as voltage being correct over a long period of time.

According to Ray, the older bricks always fail the same way, so this saver he makes is setup to prevent that failure from causing damage on the 5VDC line. The 9VAC line comes directly off the transformer, and isn't likely to be bad - unless the PS has been shorted, then the internal fuse blows.

I have a couple of the power supplies that came with the RAM expansion, and they don't fail like the old style bricks do - but then again, the size of the brick is almost double the size of the old ones! Also, this solution is not for everyone because those power supplies are tough to find, and pretty expensive!

June 13, 2014

Hi,

I'm new in the TI hobby, but I've had 4 consoles apart in the last few weeks, and EVERY one has a problem with the cartridge port. The little 'felt' piece inside of the port is deteriorating and turning into some type of sticky oily substance.

I even have one that looks white and new, but on closer inspection, it's soaked with this oily substance! Once the deterioration gets advanced, the 'felt' turns brown and starts breaking off and getting inside the cartridge and the cartridge port.

I would highly recommend taking your TI apart and popping off the right angle connector, then remove the black cover piece (snaps off), then I've been taking a small straight tip screwdriver and scraping that gunk out of there, followed by a wash and dry with alcohol.

If everyone already knows about this, I apologize, but just in case, I wanted to help!

:grin:

Update - Well, I guess it isn't a secret - here's some good pictures:

http://mainbyte.com/ti99/minimem/cart_fix.html

June 13, 2014

I'll have to check this out! I'm working on this one for a friend, and he doesn't want to spend much $$. A new mobo and keyboard would run $65 before shipping, so I may have to buy the keyboard and mobo connector and work with that. It should be a quick solder job!

June 13, 2014

I had a console with one or more bad RAM chips. Like the OP, I removed all of them, socketed the board and installed new replacement chips. After all that, it still didn't fire up and I never did track down the problem. I still have the console stored away, it seemed a shame to waste all the work and parts.

My answer to that setback was to stock up on spare consoles. I think I have 5 now; that one, another dead one and three still working. Two basic PE boxes with multiple floppy drives, plus speech and EXB for each. Back when I used it to handle my darkroom print processing, a working and reliable TI was literally indispensible! Not to mention helping with the books and officework, plus all the after-hours "fun" stuff I did with it.

Glad you got yours running! My first thought would have been to check for bad solder joints or bridges on all those socket pins. I gotta also wonder if those other problems you found weren't part of the fail that caused you to replace the RAM in the first place?

"A,S,D,F,G" Aren't these keys all tied to a common matrix connection? In which case, a simple keyswitch cleaning won't help (but can't hurt). The key layout is easy enough to find. Either a bad trace or perhaps a blown diode on that line? Spare keyboards are no problem to find if that's the easy cure.

-Ed

Sounds like a good setup! I've only got one working out of the 4 I have. I did check the RAM that I pulled, and only one was dead. Well, at least it's all socketed now so I can just pop them out if they die!

You are correct on the connection - I found a 'surgery' page here:

http://nouspikel.group.shef.ac.uk/ti99/surgery.htm

This led me to double check the wires from the plug to the keyboard, and wire 3 was actually broken where it connected to the plug! The wire was still 'connected' for all appearances - so without a meter you would have never guessed it to be bad.

The info I used was:

The keyboard connection cable is fairly fragile. If one of the wires gets loose you will notice that a whole row or column of key stops responding. Refer to the following matrix to find out which wire is damaged (the red wire is #15):

Key Wire

= . , M N / #5

space L K J H ; #4

enter O I U Y P #1

9 8 7 6 0 #2

fctn 2 3 4 5 1 lock #7

shift S D F G A #3

ctrl W E R T Q #10

X C V B Z #11

#12 #13 #14 #15 #9 #8 #6

In other words:

1 Keyboard row 2 (enter O I U Y P)

2 Keyboard row 3 ( <nc> 9 8 7 6 0)

3 Keyboard row 5 (shift S D F G A)

4 Keyboard row 1 (space L K J H ; )

5 Keyboard row 0 ( = . , m n /)

6 Keyboard alpha-lock key

7 Keyboard row 4 (fctn 2 3 4 5 1 alpha_lock)

8 Keyboard column 5 ( / ; P 0 1 A Q Z)

9 Keyboard column 4 ( N H Y 6 5 G T B)

10 Keyboard row 6 (ctrl W E R T Q)

11 Keyboard row 7 (<nc> X C V B Z)

12 Keyboard column 0 (= space enter <nc> fctn shift ctrl <nc>)

13 Keyboard column 1 (. L O 9 2 S W X)

14 Keyboard column 2 (, K I 8 3 D E C)

15 Keyboard column 3 (M J U 7 4 F R V)

I like to post this kind of stuff because someday that page may not be available, then you will just hit a dead link and never get the info...

There is a TON of TI information on those pages...

I hope this helps the next traveler looking for keyboard information.

As for my other keyboards - one confirmed dead, even after cleaning. It's a Mitsumi, and only 4 or 5 keys work on that one. Also, I did check the cable - they are all connected!

Thanks for the help everyone!

June 13, 2014

I myself got a TI99 console with bad video ram, got to do the same thing, any good sources for those video ram dram chips?

You can order them new at Jameco - .89 each if you buy 10 or more (.99 if you don't). There is also a guy on ebay selling working pulls for a good price too if you can get people to NOT bid on them!

June 12, 2014

Ok,

I ended up having several problems that combined to make this happen -

Cartridge port - that little foam insert that used to be there has deteriorated and turned into a sticky mess - this stuff was on the cartridge and in the port. Cleaned.

Cartridge port on motherboard - had some green oxidation on several of the pins. Cleaned.

GROM 1 & 2 - had a brownish oxidation on the pins. I used my brass brush on both of them and now the problem as cleared up!

Now my only problem is non-working A,S,D,F,G keys. It's the switch type keyboard, and I sprayed the non-working keys with some contact cleaner, but they are still dead. I'm going to make sure that the cable that connects to the motherboard doesn't have any breaks or tears as advised in another post.

June 12, 2014

Hmmm... I'll check that out. Thanks!

June 12, 2014

Hi,

I just swapped out all 8 RAM IC's with sockets and new RAM, now when I power on, I get the intro screen, I press a key and it gives the message "Insert Cartridge". Any cartridges that I have tried do not work - the screen goes crazy after the intro screen.

I understand that the message to insert the cartridge relates to GROM 0 (I read that if you remove GROM 0 you get this message). Anyone have a source for these, and if that's bad, shouldn't the cartridges still work?

Thanks!

June 12, 2014

Thanks!

I'll copy/paste it there now!

June 12, 2014

Best has complete New 800XL motherboards on sale for $39. Not worth fixing if there's any significant damage.

Wow - that's a pretty good deal! Are they populated with IC's as well?

June 12, 2014

Hi,

I just swapped out all 8 RAM IC's with sockets and new RAM, now when I power on, I get the intro screen, I press a key and it gives the message "Insert Cartridge". Any cartridges that I have tried do not work - the screen goes crazy after the intro screen.

I understand that the message to insert the cartridge relates to GROM 0. Anyone have a source for these, and if that's bad, shouldn't the cartridges still work?

Thanks!

June 12, 2014

Nice link - I'll have to send a PM to see if they still have a ton of them left!

Robert - good idea! I'll make sure that it's not something like that instead of the keyboard internals!

June 11, 2014

I've searched about tips for repairing TI-99/4A keyboards, but I haven't found much information. Mostly the advice is to replace the keyboard.

The type I have has the plastic sheets with the contact points on them. I tried a clean and that didn't really do anything. I have a couple of TI's, and none of the keyboards are working fully. One of them has keys that look a little different than the regular ones. The font is different or something. I'll take a pic when I get a chance.

Anyway, if anyone has any tips for getting one of these working, let me know! Also, I'm looking for a couple of black key keyboards. I'd take a beige key one if no one has any black ones to spare. I'd rather have a working TI than one that's color matched and only has 6 keys working!

Thanks!

June 11, 2014

I have one of the external Power Savers, and have installed internal ones in every one that I have fixed. Nothing makes you feel better than knowing that the old brick isn't going to fry your RAM!

June 9, 2014

Great information! Thank you!

I've located a keyboard and connector from BEST (thank you all for the tip!) - still thinking about if I really need the keyboard - but then there's a minimum $20 order, so I'll have to shop around on there and see if I can find some other stuff. I really can't tell if the keyboard is bad or not since the mobo plug is in such bad shape.

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