kodak80 H4 build (x2)

[kodak80]

Okay, I have resoldered the ROM pins and check continuity and resistance on address and data pins and they all test fine but still getting the wrong address. Any suggestions?

[exxos]

This is basically the problems derkom had with a bad joint somewhere... Have you read though his thread ? everything we could suggest is already been mentioned in that one.

[kodak80]

Removed the SIMM and re-tested the address and without RAM. This now reads as:
1111111100001110

Now re-soldering the SIMM pins...

[exxos]

Removed the SIMM and re-tested the address and without RAM. This now reads as:
1111111100001110

Now re-soldering the SIMM pins...

If your using a simm, did you do the fix for that ?

[kodak80]

Yes, patch on the SIMM pins was done.

After re-soldering the SIMM socket, I now have one address on SIMM and the other when using the Falcon RAM card.

[kodak80]

I am pleased to announce the birth of another working H4 board. Washed out video even with 150R resistors on the RGB signal instead of the 75R ones.

Special thanks to @PaulJ for the DiagROM file as this was a great help in fixing the issues I had.

070FE530-DB35-4909-A6C6-84457640806A.jpeg

1B3218BF-1372-4CA8-832C-054969E48DC6.jpeg

[exxos]

:bravo: try those big smt caps in series with the 75R like @PhilC did and see if it solves the issue.

[PhilC]

I had to reset my monitor back to default settings as well for it to look better.

I'll probably try some bigger resistors too when I'm back home.

[PaulJ]

Congrats on the birth of your second H4. :thumbup: :thumbup: :thumbup:

[kodak80]

Congrats on the birth of your second H4. :thumbup: :thumbup: :thumbup:

Thanks, it is actually my first board that is now booting up. My second board is under way but unlikely to be built this weekend as I am missing some capacitors which are on there way to AU.