exxos's Atari, Amiga & retro forum

Yes, all fixes done and double checked this time, no shorts and proper continuity on all the fixes.

Some progress, the Mono/RGB issue is linked to my UBE Switch. If I use a standard SCART, no more reboot and picture is clean and stable in both high res and low res.
I suspect the UBE switch get confused and keeps switching Mono Detect on and off, which in turns generates reboots. This UBE switch works flawlessly with other STs including my other H5 though... I will need to check why it behaves strangely with this specific H5.

Now the keyboard issue: Keyboard is detected as it works well with diag cart and there are no « beeps » when not using diag carts (jumper is properly soldered, so it should beep).
I suspect TOS initialization code for 6850 is not applied properly, so need to check all connections to the ACIA.

The H5 has a built on UBE type switch .. You would just need to solder a VGA connector in the H5..

Yes, realized that when building the second H5 but I had no connector available. I just ordered some.

For the keyboard issue, it’s really weird:
- Case #1 Diag Cart with keyboard: IRQ line fro 6850 is pulled high and goes low only when a key is pressed, normal behaviour (same on a different ST).
- Case #2 Diag Cart without keyboard : IRQ line for 6850 is pulled high for 3.5s after boot, then it goes low and stays there, normal behaviour.
- Case #3 TOS 1.4 with or without keyboard: IRQ line for 6850 is pulled high for 3.5s after boot, then it goes low and stays there!

Checking communication between keyboard and ACIA shows proper dialog for config of the keyboard. Key press shows also, scan codes being sent to ACIA, whatever the scenario.

I swapped ACIA and ROM with a known good machine, but no change.

So,I guess there is something wrong during TOS init, but I’ve no clue where to look next. I guess it’s going to be logic analyzer and comparison of the results between two machines, but 3.5 secs is a long long time in terms of bus activity.

exxos wrote: 28 Feb 2021 10:38 The H5 has a built on UBE type switch .. You would just need to solder a VGA connector in the H5..

Got the VGA connectors, but if I replace the standard connector, I need to solder an audio jack somewhere on the original connector's socket(Pin 1) and there's no space for a jack on the motherboard, or did I miss something ?
It would be great to be able to solder a jack in front of the RF output for those having an STFM case.

olivier.jan wrote: 02 Mar 2021 11:25 Got the VGA connectors, but if I replace the standard connector, I need to solder an audio jack somewhere on the original connector's socket(Pin 1) and there's no space for a jack on the motherboard, or did I miss something ?
It would be great to be able to solder a jack in front of the RF output for those having an STFM case.

hmm yeah, thats a point, I don't think anyone thought about audio when using VGA... I guess bodge wire the audio line somewhere and use a chassis mount jack on the case...

exxos wrote: 02 Mar 2021 11:37 hmm yeah, thats a point, I don't think anyone thought about audio when using VGA... I guess bodge wire the audio line somewhere and use a chassis mount jack on the case...

@olivier.jan - something like this - https://www.exxosforum.co.uk/forum/viewt ... =20#p55052

Icky wrote: 02 Mar 2021 12:15 @olivier.jan - something like this - https://www.exxosforum.co.uk/forum/viewt ... =20#p55052

Yes, very nice. No 3D printer here, but I should be able to do something with Multimorph plastic. Will try this over the week-end if I manage to fix my keyboard issue first.

I was going to start a long debugging session with the logic analyzer this morning to identify my keyboard issue, but under the shower, an idea came up: my issue is with the 6850 IRQ line staying low, this IRQ line is shared between the two 6850, could it be the MIDI ACIA having a problem ?
Bingo, removed the MIDI ACIA and keyboard works fine both with diag cart and with GEM.
Put back ACIA and removed Opto-coupler, keyboard works fine too.
So, mistake is pretty simple here: As I didn’t follow all the threads about H4, I never noticed th Opto-coupler on H4 and H5 have a different pinout from the original ones and I used one pulled from the donor machine.
So this one is fixed (or will be when I get a new Opto coupler) and the H5 boots nicely.