Problem with H4 not booting (zChris's board)

[PhilC]

@zChris there certainly looks to be solder or other debris behind the pins. Have you tried carefully pushing each pin to make sure that none are loose?

[zChris]

@zChris there certainly looks to be solder or other debris behind the pins. Have you tried carefully pushing each pin to make sure that none are loose?

Yeah checked now. None is loose.

/zChris

[PhilC]

@zChris Also just looking at the PCB, can you please check PIN number four on the top left side of the glue. It looks like it may have a broken track? you could try metering between the via and that pin to make sure there is a good connection.

[zChris]

@zChris Also just looking at the PCB, can you please check PIN number four on the top left side of the glue. It looks like it may have a broken track? you could try metering between the via and that pin to make sure there is a good connection.

It was just some dirt. Sorry about the bad state of it all i have tried to take a better photo.

2021-08-19_22-41.png (3.11 MiB) Viewed 2684 times

[PhilC]

@zChris OK, That looks much better.

Have you been through the troubleshooting page that @exxos did?

https://www.exxosforum.co.uk/forum/viewt ... =78&t=2362

It may be that with handling of the board that some of the connections have gone bad, so start by removing the CPU and try all the pull-ups with the power off, then work through the rest. It really has to be something simple as this board ran really well when I had it.

Also, I know it may sound daft to ask but remove your rom chip, turn it upside down and sent me a photo of it like that please

[zChris]

@zChris OK, That looks much better.

Have you been through the troubleshooting page that @exxos did?

https://www.exxosforum.co.uk/forum/viewt ... =78&t=2362

It may be that with handling of the board that some of the connections have gone bad, so start by removing the CPU and try all the pull-ups with the power off, then work through the rest. It really has to be something simple as this board ran really well when I had it.

Also, I know it may sound daft to ask but remove your rom chip, turn it upside down and sent me a photo of it like that please

Ive done all except the last one first bus cycle since it seemed to complex for me. Ill send you a pic right away.

/zChris

[PhilC]

@zChris I'd work through the first bus cycle bit as much as you can do, it will take quite a while but again will rule it out

[exxos]

There is another way which I've not tried.. But if you remove the CPU, and hardwire all the address lines to 0V, LDS,UDS,AS also..

Idea as adress zero should trigger the GLUE to set ROM2 low for some time after power up. So you should see the binary pattern as stated in my troubleshooting page.

[zChris]

There is another way which I've not tried.. But if you remove the CPU, and hardwire all the address lines to 0V, LDS,UDS,AS also..

Idea as adress zero should trigger the GLUE to set ROM2 low for some time after power up. So you should see the binary pattern as stated in my troubleshooting page.

Hardwire to 0v, is that the same as ground them?

/zChris

[exxos]

Hardwire to 0v, is that the same as ground them?

Yep.