Ti-990

[zippysticks]

Could somebody with a ti-990 system with a programmers panel take some pictures of the rear of the panel, i'm hoping it has some component designations on for the LED, it's not clear from the schematic if they are in the same order as they are on the panel.
I'm building a pcb for a replica programmers panel to connect to my 990/10A processor board.

Many thanks,

Jim

I have a panel - will try and get some pictures for you this weekend.

 

[Jim Hearne]

I have a panel - will try and get some pictures for you this weekend.

Thank you very much, hopefully there is a silkscreen on the rear of the PCB

 

[zippysticks]

No silkscreen on the rear of the PCB, and this is the best shot I can shot without dismantling the PCB from the front panel. reluctant as I don't want to have to faff about aliging all the LED's and switches back up.

 

[Jim Hearne]

Thank you very much, that should do, since i have the schematic hopefully i can trace the tracks from the LED's back to the shift registers on the picture.
I only need to be able to trace a couple to confirm the led order.

I wouldn't expect you to take the PCB off.

Thanks again,

Jim

 

[zippysticks]

Let me know of you need anything else. I'm preparing to power this baby up tomorrow - at least for some large PSU cap forming for a few days.
A previous owner had cut off all the mains power cables and removed fuses - I'm hoping it was just a precaution before offloading the machine rather than a sign of something more sinister.

 

[Jim Hearne]

Thank you, I have been able to follow enough tracks on the picture to confirm what i needed to know.
Despite the LED's being labelled (left to right) as Bit 8 to Bit 15 and then Bit 0 to Bit 7, that is the correct order.

Funny how they used 4 x 5 keypads (only using 2 rows) for the switches, i wonder if they were they same as there calculators.

Good luck with your power up.

Jim

 

[Jim Hearne]

Here is my recreation of the programmers panel for use with the 990/10A pcbs.
It's not intended to be an exact copy, it's smaller and i have used SMT caps and resistors. But the circuit is 100% the same.
Just ordered some boards.

 

[zippysticks]

Very nice - let us know how you get on.

Made some progress with my system at the weekend. I have managed to rewire the entire AC mains supply and it is now working - at least beyond the huge 240v->115v mains transformer, filters and to the AC power conversion board. Hope to get more time this weekend to get into the DC. Three 115V fans in the chassis are incredibly loud.