Luis' Build

[exxos]

I don't think the YM chip would stop booting. Did you get the CPU from my store ? Normally they have a QC sticker on them. While I have no objections to where people get parts, a lot from China are faulty. So I just wanted to cover the basics first. Similar with the ram, again, do you really know it works ?

Like I said earlier https://www.exxosforum.co.uk/forum/viewt ... =78&t=2362 you will have to start some trouble shooting, of course double check there is no shorts on the board, or anything alike.

[lrodriguezrullan]

Yes. I purchased the CPU from your store. That should be good.

I am not sure about the SIMM. I got it on eBay, so it may not be good.

I completed the following troubleshooting steps as you recommended:

Reset Test - OK. I measured from pin 16 to 18 on one of the CPU sockets. On boot, after a short delay, it went from 0V to 5V. Pressing reset, it went to 0V for a short delay and then back to 5V.

Pull Ups Test - Not sure. All pins as expected, except pins 12 (1.5K) and 53 (0.93K). Not sure if these are OK.

Bus Shorts Test - OK.

LS11 Test - Not sure if I measured in the right place. I measured from the top left pin of the glue chip to the three pins to the right of the U2 (?) chip, as described on the "Problem with H4 not booting (zChris's board)" thread. Got 0 resistance.

First Power Voltage Test - Not sure. All pins as expected, except pins 23 (0.15V) and 28 (0.05V). Not sure if these are OK.

Should I get another SIMM?

[exxos]

You could try another one. Though a diagnostic cart is your only option currently I think.

I would check soldering on the simm socket, 32mhz osc, check it's running.. There really isn't much to getting a H5 running.

I will also try and post a new test when I can verify next week (I'm not at home right now). But you will need ideally a 68k dip socket in place.

[lrodriguezrullan]

I'll try a new SIMM from your store.

Thanks!

[exxos]

Here'ya go https://www.exxosforum.co.uk/forum/viewt ... 084#p79084

[lrodriguezrullan]

Thanks. I will take a look at it.

[lrodriguezrullan]

I got the new SIMM from your store. Still getting a white screen. Did the test with the 68K DIP socket and got 11111 on pins 1-5 of the CPU.

[exxos]

Did the test with the 68K DIP socket and got 11111 on pins 1-5 of the CPU.

Need to know the full bus results..

[lrodriguezrullan]

Hi. I got all ones from D0-D15. :cry:

[exxos]

Hi. I got all ones from D0-D15. :cry:

ROM clearly isn't working then. What do you get on the ROM jumper above IO port #1 ? I assume its at 5v ?