exxos's Atari, Amiga & retro forum

PhilC wrote: 10 May 2021 13:18 @rubber_jonnie I was talking shifter chip into adaptor board

But agree, forget that and get it running without to see if it still works.

We're definitely in agreement then!

I did as you suggested and resoldered into place the onboard RAM and turned on the system and it boots up.


As a side note: the purply color is somehow caused by my convertion to SCART to HDMI, as it happens with my other 1040 STFM.

I still have the shifter chip on the board and plugged into the socket, so I assume that shows that there is nothing wrong with the shifter chip or board. That leaves me with the MMU component, I would guess. I don't see any issue physically, with the MMU board.

Any suggestions on next steps?


Regards,
Malcolm

Place the ribbon cable in the shifter board and check from the free end of the cable to the shifter pins and make sure all 16 wires have continuity , with the power off of course ...

I tested the continuity on the pins leading to the ribbon cable port and the far end of the ribbon cable, that would plug into the MMU. There was continuity on all pins.


I tried testing continuity from the pins on the shifter IC itself and there is not continuity from those pins to the end of the ribbon cable, but I'm not sure if that is what you were referring to.


UPDATE: I tried reconnecting the ribbon cable (no clue if it led to or caused this), but now I am getting a constant "trilling" or "RRRRRRRR" sound from the computer when I power it on. I disconnected the 4MB RAM from the MMU, but it is still occurring.

With that purple background it looks like you've bad connections on the shifter, in this case specifically the red output, but there could be others. Check those pins!

@kmcrainey

You still haven't addressed the issue of the 5 pins on the Shifter's right hand side (Same side as the connector on the Shifter adapter) that are not properly in the socket and are possibly the cause of your purple screen.

You need to get these fundamentals right before moving on to the next thing, or you end up with one problem layered on another.

Steps I'd advise:

1. Put the machine back to its known working condition.
2. Remove the Shifter from its adaptor and straighten the legs, being careful not to snap them.
3. Replace the Shifter into the adaptor making sure you have the pins straight and properly in the socket.
4. Replace the Shifter Adaptor complete with Shifter onto the mainboard.
5. Test to make sure you have restored the screen to correct colours.

Then return to the 4MB RAM expansion installation, because then you'll know the Shifter adaptor is working for the shifter part of the install.

You're on the wrong side of the shifter...pinout is here https://www.exxosforum.co.uk/forum/viewt ... =10#p60270

I did mention earlier that I believed the purple border is a result of the video convertion from DIN to SCART to HDMI. Just to make sure, I hooked it up to my original Atari monitor and the boarder is not there:


Does this normal image show that there is no issue with the shifter chip as it is attached to the shifter board? Is that's the case, that just leaves an issue with the pins leaving the shifter board, the the lines through the ribbon cable, the pins entering the 4MB ram board that is on the CPU, The way the 4MB ram is situation on the upgrade board, and finally the way that the 4mb board is set on the MMU.

Please let me know if I am correct in ruling out the shifter IC and the shifter board, excluding the ribbon cable port.

I am also still getting this "RRRRRRRR" sound continuously now for audio, which only started happening yesterday after reconnecting the upgraded RAM. I resoldered the on board RAM, computer booted up fine. Then I attached back the ribbon cable from the shifter board to the MMU and now this constant sound. I don't know if it's related to the ribbon being rehooked up, it's just what I did before it started happening. Any ideas on what could cause this and how I can fix this?

As the problems are mounting up, I suggest you send your board to @Steve to repair before things get any worse..