PhilCs blog / the latest things hes broken(fixed)

[rubber_jonnie]

@JezC i don’t think @Icky has anything to worry about with my old engineers hands.

My thumb has been in the wars recently. The new puppy has been at it.

Icky got an owie

[PhilC]

Annoyingly, the TI-99 that I'd fitted the new ram and rom chip to decided it was going to play up. When left running for a couple of minutes the screen would start getting corrupted and then lose sync.

So one of my Chinese spare parts arrived today, I ordered a new TMS9929ANL chip and thought I'd test it on the dodgy TI. Well the good news unexpectedly is that fitting that actually cured the issue with the TI.

So one very simple

10 LET P = 1
20 PRINT P
30 LET P=P+1
40 GOTO 20

and its still running just fine but boy is it slow, we're only up to 4119ish at time of writing. I can't remember these computers seeming this slow back in the day?

[rubber_jonnie]

Annoyingly, the TI-99 that I'd fitted the new ram and rom chip to decided it was going to play up. When left running for a couple of minutes the screen would start getting corrupted and then lose sync.

So one of my Chinese spare parts arrived today, I ordered a new TMS9929ANL chip and thought I'd test it on the dodgy TI. Well the good news unexpectedly is that fitting that actually cured the issue with the TI.

So one very simple

10 LET P = 1
20 PRINT P
30 LET P=P+1
40 GOTO 20

and its still running just fine but boy is it slow, we're only up to 4119ish at time of writing. I can't remember these computers seeming this slow back in the day?

What have you got against for/next loops

Glad to hear it's working

[PhilC]

This arrived in the post today, thank you @mrbombermilzy

IMG_2723.jpeg (221.37 KiB) Viewed 979 times

As you can tell I have all my tools to hand to take it apart and get it working again. But if that doesn’t work I have a pair of 36” stilsons and a large axe in the shed for those stubborn case screws.

[PhilC]

First plug in and

IMG_2724.jpeg (778.57 KiB) Viewed 976 times

Hoping it’s something simple like a memory error but we will soon see once I open it up.

[PhilC]

So I plugged the electron in, got the Scope ready, logged off from my work pc and BEEP, I about jumped off my chair.

It will now boot to desktop but takes a very long time about it, so I think I shall be checking the reset circuit first. PSU seems ok at 4.96V and -5.02V.

Edit:

Whoops, if you plug the keyboard in it now boots right away, time to leave it off for a mo but still check the reset caps. Only other thing I've done is to check and clean the ULA.

[PhilC]

And it won’t go wrong at all now, well that was disappointing, I was hoping for more of a challenge.

It does look lovely and clean inside too, so now I’m off to try and find a tape lead for it.

IMG_2726.jpeg (340.66 KiB) Viewed 963 times

[rubber_jonnie]

So I plugged the electron in, got the Scope ready, logged off from my work pc and BEEP, I about jumped off my chair.

It will now boot to desktop but takes a very long time about it, so I think I shall be checking the reset circuit first. PSU seems ok at 4.96V and -5.02V.

Edit:

Whoops, if you plug the keyboard in it now boots right away, time to leave it off for a mo but still check the reset caps. Only other thing I've done is to check and clean the ULA.

Is that wrench for percussive maintenance?

I would have a look at the electrolytic caps in the internal part of the PSU, obviously there's not much to be done with the external AC part of the PSU. Mine were a mess and had to be replaced.

[PhilC]

So I plugged the electron in, got the Scope ready, logged off from my work pc and BEEP, I about jumped off my chair.

It will now boot to desktop but takes a very long time about it, so I think I shall be checking the reset circuit first. PSU seems ok at 4.96V and -5.02V.

Edit:

Whoops, if you plug the keyboard in it now boots right away, time to leave it off for a mo but still check the reset caps. Only other thing I've done is to check and clean the ULA.

Is that wrench for percussive maintenance?

I would have a look at the electrolytic caps in the internal part of the PSU, obviously there's not much to be done with the external AC part of the PSU. Mine were a mess and had to be replaced.

Yes, whenever you can't find a hammer, use your Ridgid Stilsons, larger bang, the bigger the pair. This only needed a little tweak, so that 18s came out

[rubber_jonnie]

And it won’t go wrong at all now, well that was disappointing, I was hoping for more of a challenge.

It does look lovely and clean inside too, so now I’m off to try and find a tape lead for it.

IMG_2726.jpeg

I believe what you need is an ElkSD