MC68HC16Z1 troubleshooting

[tony359]

Hello all,

As a fun project I am troubleshooting a system board of an old sound processor which is featuring a MC68HC16Z1 microcontroller. The board seems dead. I have good clock and the reset line is ok but I see no activity whatsoever anywhere.

This is a total fun project and it's probably beyond my capabilities but I am just having a go. I'm building some cables to extend the board out of its chassis so I can probe it more easily but does anybody have any troubleshooting tips on this chip? Am I expected to see any activity on the address lines or data lines meaning that the processor is trying to read the program or could a faulty eeprom or RAM result into a completely dead system?

Thanks for any tips you could have!
Tony

[ale500]

The manual of the microcontroller is still available, have a look at it. It is an "enhanced" HC11/HC12 with true 16 bit registers. The Bus is asynchronous like in the 68k, and not synchronous like in the HC11. Post some pictures of the board .

[tony359]

Hi Ale500,

Apologies for not following up. I just wanted to let the community know that I eventually managed to observe some brief data transfer on the data lines at power up so I assumed the CPU was attempting to do something. I realised a memory module was VERY warm and I had 27 Ohm between VCC and ground.
Once the memory module was replaces the board came back to life!

I now have a digital scope, I'm confident it would have been much easier to spot that activity!

Thanks again for your help and sorry for disappearing.

[Bassman59]

I bet that those two big empty sockets in the middle of that board are EPROMs, and those EPROMs held the program memory for your processor. I think you're dead in the water.

[tony359]

Bassman,

Indeed! I just don't have EEPROMS for all my boards so I have been swapping them around. I happened to take a picture of a board that doesn't have the EEPROM but don't worry, I am aware the board won't start without those chips

[Benta]

The board looks like it's VME format. Looks nicely built too.

[ale500]

I'm glad it was that easy nice to see the 68HC16 being used somewhere.