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 (342.03 KiB) Viewed 4249 times

1B3218BF-1372-4CA8-832C-054969E48DC6.jpeg (207.01 KiB) Viewed 4249 times

[exxos]

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.

[kodak80]

Congrats on the birth of your second H4.

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.