exxos's Atari, Amiga & retro forum

@stephen_usher Looks like it might be time to update that list of machines in your signature... ;)

Hehe

Looks like the TI 99/4A has bad 4116 display RAM.

When I very first turned it on it was OK for a couple of seconds and then more and more of the display became corrupt and stayed corrupt in that way when power cycled. Not surprising. 4116 RAM is notoriously bad.

stephen_usher wrote: 12 Mar 2022 19:28 IMG_2617.jpg
The TI 99/4A is in mint condition with not even a hint of a fingerprint on the aluminium.

Wow!! Just like new :)

Well, pulled the machine apart this morning and replaced the bad video DRAM.

One chip was obviously bad with the output being a few millivolts. Replaced that and things got a bit better. One other chip was behaving slightly strangely when viewed on the 'scope so replaced that and...


Happy machine! :-)

My experience with the Memotech MTX helped here as it uses the same graphics sub-system so it was obvious to me what the fault was.

And this afternoon checking out the Mac LCII as much as I can without being to re-cap the power supply (which is mostly dead) as Sod's law states that in my large stash of capacitors I have none which match those in the power supply.

So, rigged up the bench power supply for 5V. All fine as far as I can tell.

That TI is really nice :)

As for the LCII I had an LC475 a few years back and ended up getting rid of it as I just didn't have enough space, and now honestly wish I hadn't!! It's a scenario that's played out a few times for me over the years, and I'm happy to finally be over it!!

That is an impressive and very nice haul :mrgreen:

I'm going to be giving away the TI. I'd never use it for exhibitions and the two games carts are awful arcade clones.

After that power test on the LCII I noticed that a couple of the surface mount caps had belched their guts, so I had to clean up the electrolyte.

I've got a full set of the surface mount caps on order now, along with a full set of the power supply low voltage side ones. They should arrive on Tuesday.

The LCII isn't fastest machine on the planet. It was definitely a Low Cost machine. Only 4MB of RAM on board. I'll have to find out what sort of SIMMs it takes.

stephen_usher wrote: 13 Mar 2022 17:49 I'm going to be giving away the TI. I'd never use it for exhibitions and the two games carts are awful arcade clones.

After that power test on the LCII I noticed that a couple of the surface mount caps had belched their guts, so I had to clean up the electrolyte.

I've got a full set of the surface mount caps on order now, along with a full set of the power supply low voltage side ones. They should arrive on Tuesday.

The LCII isn't fastest machine on the planet. It was definitely a Low Cost machine. Only 4MB of RAM on board. I'll have to find out what sort of SIMMs it takes.

Lovely caps!! Apple seemed to have a particular talent for putting crappy caps in their machines of this era.

I think what I liked about the LC was the form factor, it's really neat. I actually acquired a number of LCs, the 475 included, from a school that had a huge pile in the basement. I knew a guy who worked there, and he said I could take what I wanted, so I think I took the LC475 and another 3 machines, plus matching CRTs. I really regret getting rid of them, and though the 475 had its own specific set of problems, it was a nice little machine, and the CPU looked glorious in all its ceramic finery!!

I may try and find another 475.

The TI is one of those machines I say 'I want one of those' and when it comes to the crunch, I get other stuff instead. I always remember going to Liverpool with my parents, and one of the department stores had the TI along with Ataris and Commodores, and I always thought it looked fab, but it was just too expensive, hence why I ended up with an Atari 600XL in the end.

Yeah, the TI is quite limited. It's got a very tiny amount of built-in RAM which rather hobbles the 16 bit processor. It was really designed with cartridges in mind, the BASIC is just a place holder.

The LC475 is really sought after as it's the fastest of the m68k Macs and the motherboard can be fitted into a Mac Color Classic.