New TI-99/4A owner here, with some questions.

[Cheshire Noir]

Hey Folks,

New here, so I apologise if I'm off base at all.

I have some hardware questions, but first a little background 🙂 
I'm a "general" collector of 8 and 16 bit retro systems, triggered by a friend of mine giving me an Amiga CD32 about 8 years back. (Up until then, I'd been a fan of retro emulation). I'd been slowly growing my collection of "core" systems to cover the majority of 8 and 16 bit systems to the point where I was really only missing two main systems, that being the TRS-80 Model 1 and the TI-99/4A.
Then the past weekend, while going through, cleaning up a "trashpile" of old systems, I managed to find a Dick Smith System 80, which is a clone of the TRS-80 Model 1, as well as a pair of TI-99/4As! (One beige and one silver)
 

Back to the TI-99/4A, neither system came with modulator or power supply. 

I've been looking into my options for getting power in and picture out, but until I know the units are actually working, I don't want to put too much money into them. I'm also in Australia (PAL region) so ordering stuff from Ebay tends to mean I pay twice what the goods are worth in shipping, so DIY is my preferred option.

 

On the power front, I was thinking of getting a suitable MeanWell and use it to bypass the internal regulator entirely... It'll work in my initial testing. The other alternative I have is I can get a transformer locally that's rated for 2A that has a 18V outer and 9V center tap I could possibly use? Is the extra 0.5v on the smaller winding going to be an issue?

On the video front, well, that's more of an issue. I know PAL units do a "component" out. What are the chances I can feed that (Possibly with suitable resistors) into a Component capable monitor? (I have an old LCD TV I use for a lot of my systems)

Anyway, great to enter the TI club, even if my systems don't yet work 🙂

 

Cheers!

 

Chesh

[Hans23]

10 minutes ago, Cheshire Noir said:

On the power front, I was thinking of getting a suitable MeanWell and use it to bypass the internal regulator entirely... It'll work in my initial testing. The other alternative I have is I can get a transformer locally that's rated for 2A that has a 18V outer and 9V center tap I could possibly use? Is the extra 0.5v on the smaller winding going to be an issue?

The console will get maybe a bit hotter in the power supply region, but it won't be damaged by the slightly higher voltage.

 

11 minutes ago, Cheshire Noir said:

On the video front, well, that's more of an issue. I know PAL units do a "component" out. What are the chances I can feed that (Possibly with suitable resistors) into a Component capable monitor? (I have an old LCD TV I use for a lot of my systems)

None of the YuV monitors that I tried would be able to display the signal coming out of the TMS9929A directly.  One way to get a usable signal out of the machine is to use a tms-rgb board, which is soldered under the TMS9929A and provides for RGB output.  Another is to build or get an F18A, which provides a VGA and also has some advanced capabilities like better sprites and 80 chars/line support.  For simple composite video output, getting the original modulator seems to be the most sensible approach.

[ti99iuc]

@Cheshire Noir Hello and welcome in the TI community  
for the PAL version of the TI99 you have some additional solutions over the ones descibed from @Hans23

 

1) The easier free one is to build a Composite Cable using only the Y (green) signal, btw this will be a Black&White signal only but at least you can check if your TI99 works good.
anyway this is the schematic pin-out to build a complete Component Cable if you want to try (I have tried several monitors/TV and on someone it works perfect but you can't know until you will try):

2) If you have also the modulator PHA2036/2030 you can easily modify this to obtain a composite signal:
https://www.ti99iuc.it/web/index.php?pageid=119&pagina=mod_proj1&sezione=4&data=Mod_and_Tuneed

 

3) The PHA2037 RGB Scart Interface
This is the French version Modulator and has a Standard RGB signal with SCART

4) The Italian User Club with the help of Fabrizio Corpetti have also the updated version of the PHA2037 named miniPHA2037.
It is smaller than the original one and it is also optimized to work also with LCD Monitor/TV, it also has a Line-Out female RCA to connect additional external speakers if needed.
(actually I have finished in my store but you can contact Fabrizio Corpetti following the instructions in the link:
https://www.ti99iuc.it/web/index.php?pageid=homepage&artid=214

 

 

4) The F18A is a best solution for the VGA signal and also additional features, if you want you can read the review that I wrote when this was released
https://www.ti99iuc.it/web/index.php?pagina=articoli&artid=56

 

 

 

Edited October 19, 2022 by ti99iuc

[Cheshire Noir]

Thanks @Hans23 and @ti99iuc!

OK the transformer looks like a cheap way to test the system powers up and is relatively cheap and available locally. I can also get the parts for the simple mono video out as my first step 🙂

 

Once I know one of them is working, I can start looking at better solutions.

 

Unfortunately both came with nothing. I pulled them out of a "junk pile" of old electronics. So far, of the machines I salvaged, 2 work, 1 partially works and 1 is dead. The TIs are next on my test list 🙂

 

Chesh

[+arcadeshopper]

Others have chimed in, but all this info is in the FAQ.. Power requirements, video options.. etc.. 

 

[Tuxon86]

7 minutes ago, arcadeshopper said:

Others have chimed in, but all this info is in the FAQ.. Power requirements, video options.. etc.. 

 

Silly question... Will there ever be a new batch of F18A for the TI-99 available? 

 

[Shift838]

4 hours ago, Tuxon86 said:

Silly question... Will there ever be a new batch of F18A for the TI-99 available? 

 

Some of the components can be difficult to find now and pricey.  I have found a handful of the ones I needed, and I do have a few blank boards I can populate.  I just have not been able to carve out time to do so yet.

[Tuxon86]

Just now, Shift838 said:

Some of the components can be difficult to find now and pricey.  I have found a handful of the ones I needed, and I do have a few blank boards I can populate.  I just have not been able to carve out time to do so yet.

No rush really.... I just wanted to know if the project was still active. No point of suggesting it as a possible upgrade if it's impossible to source one.

[Shift838]

54 minutes ago, Tuxon86 said:

No rush really.... I just wanted to know if the project was still active. No point of suggesting it as a possible upgrade if it's impossible to source one.

i'll check some suppliers for the hard to find chips and find out if they have more stock that I can get.

[+arcadeshopper]

5 hours ago, Tuxon86 said:

Silly question... Will there ever be a new batch of F18A for the TI-99 available? 

 

I just had 20 in my store..   so yes.. but sporadically.. parts are hard to come by right now 

[Duewester]

I've heard it said that you can get your +5, -5, and 12v from a an older PC AT power supply. If you have one around, you can at least see if the 99's are worth saving. IMHO, any 99 is worth saving.

Edited October 19, 2022 by Duewester

[Shift838]

31 minutes ago, Duewester said:

I've heard it said that you can get your +5, -5, and 12v from a an older PC AT power supply. If you have one around, you can at least see if the 99's are worth saving. IMHO, any 99 is worth saving.

that is correct, not typically on the newer ATX power supplies but the older AT as you stated that have the P8/P9 connectors will do the required voltage.

 

You can use a standard ATX power supply since those are more readily available, but a circuit would need to be designed to get the -5v from the -12v line with a regulator that will do the correct amount of amps the TI requires.

Edited October 19, 2022 by Shift838

[Duewester]

I have a couple of old AT supplies. One I turned into a benchtop power supply. Just remember, there is a jumper you have to install to get them to start up remotely.

[Shift838]

24 minutes ago, Duewester said:

I have a couple of old AT supplies. One I turned into a benchtop power supply. Just remember, there is a jumper you have to install to get them to start up remotely.

i know on both of my old AT computers the power switch is a latching switch, unlike the new ATX power supplies that use momentary switches and uses a timer circuit to keep the power supply engage, much like the one I designed for my 838-PEB boards.

 

 

[Cheshire Noir]

11 hours ago, arcadeshopper said:

Others have chimed in, but all this info is in the FAQ.. Power requirements, video options.. etc.. 

 

Did read through the FAQ, but found it a little ambiguous in places around my PAL setup. Thus my checking 🙂

(For instance, I'm still not entirely confident about how to wire up an AC power supply to the system. The picture of the power pack says "18vAC / 8.5vAC" whereas the illustration of the input connector says 8vAC, 16vAC and 5vAC. I'm assuming it's actually something around 16v with a center tap at around 8v. https://www.unige.ch/medecine/nouspikel/ti99/pinouts.htm#Power suggests the white wire is the center tap...)

 

I do happen to have an ATX PSU with the -5V rail intact (An older model) so I'll try initial power up of the systems from that. I'll worry about something more reliable if they work.

 

Chesh

[Cheshire Noir]

Well, whattaya know? it works!

 

Now I can justify putting some actual $$$ into a solution.

(I'll probably keep my "rig" I built together so I can test it with the other TI, but for now, I'm pretty chuffed with the results)

 

Chesh

[Duewester]

Awesome @Cheshire Noir. Next project - get the red/yellow back into the display.

Looks like a old PC power supply still has a purpose.😎

I just realized, you have a PAL system, right?.😎 That means you have the pal version of the vdp and therefore more than one video connection out. So probably just need to hook it up to get all colors.

I guess my other question is - is that a QI version 99?

Edited October 20, 2022 by Duewester

[+mizapf]

@Cheshire NoirAnd don't forget to press Alpha Lock. Upper case is the default on the TI, in particular when it comes to device names. The last picture shows that you typed small capitals, the TI understanding of "lowercase".

[Cheshire Noir]

Heh. Thanks!

The plan for today is to see if I can get colour out of it.

It's only got the one video out port, but I'm going to see if component out works initially, and if that doesn't work, I'll look at converting YUV to RGB somehow. (I have a whole bunch of links to read through already)

@Duewester I'd never even heard of a QI version 99 before you mentioned it, so I went and looked it up and I don't think mine is. It has 3 voltage levels on the PSU, brass coloured ground fingers and a copyright date of 1981. I'll have a closer look if I have to dissect the machine any further.

@mizapf right! I was wondering what I was doing wrong 🙂 The keyboard is subtly "wrong" to me, but TBH, it's not even remotely the worst keyboard I've had to deal with. (Looking at you, CreatiVision. Also the Commodore PET doesn't have number across the top row of keys, only on the numeric keypad. Why???)

 

Once I have video sorted and the power supply less "janky" I guess it'll be time to start thinking about expanding it. As I got several other systems when I picked up this one, it could end up being an expensive year  

 

Cheers!

 

Chesh

 

 

 

[Duewester]

@Cheshire Noir, a beige 99 is always a crapshoot as to whether it might be a QI (last dying effort of Ti to compete against other computers of the time) 99 or not. The motherboard is the real tell. It's drastically different from the previous versions.

[+arcadeshopper]

14 hours ago, Duewester said:

@Cheshire Noir, a beige 99 is always a crapshoot as to whether it might be a QI (last dying effort of Ti to compete against other computers of the time) 99 or not. The motherboard is the real tell. It's drastically different from the previous versions.

correct, QI is the motherboard not the roms..so the date can still be 1981 and it could be QI, however if you have a (c) 1983 it's LIKELY a QI board..  and has the ROM program scan removed from the roms.. The only real way to tell other than opening and looking at it is the side port is steel not brass USUALLY on a QI..   

 

 

[+mizapf]

15 hours ago, Cheshire Noir said:

@mizapf right! I was wondering what I was doing wrong 🙂 The keyboard is subtly "wrong" to me, but TBH, it's not even remotely the worst keyboard I've had to deal with. (Looking at you, CreatiVision. Also the Commodore PET doesn't have number across the top row of keys, only on the numeric keypad. Why???)

As for the keyboard, I believe it was the early years of computing for me that made me prefer mechanical keyboards until today. In fact, the TI keyboard has a lot of similarity with my current Cherry linear (black) switch keyboard. The typing experience was not that bad on the TI, apart from some FCTN key combinations.

 

In contrast, I could never really understand how people managed to work some longer time with the C64 keyboard. The chassis was much higher, so you could not keep your hands resting on the table, and the keys were much harder to press.

 

(We're not even talking about ZX Spectrum's rubber keyboard...)