H5 A3 & B1 pullup resistor change

[exxos]

Revision A3 and B1 had 4.7K pull up resistors which are not adequate when using a lot of or particular add-on boards.

If you are not experiencing any issues you can probably just leave them alone..

A suitable alternative is 2.2K...

https://www.mouser.co.uk/ProductDetail/ ... ApBQ%3D%3D


Packs to change are..

Capture.PNG

Is possible just changing the databus ones may be enough to solve some issues alone.. So I was suggest just try changing those first few have problems as it may solve them...

[sporniket]

Tonight, having started my build, I could have a good look at those resistors, and it's quite tiny, and I feel uneasy to hack them.

On the other hand, we have those marvelous expansion ports, so I was telling myself that leaving alone the existing resistors, and making an extension that add another set of pull-ups resistors (4.7k too) in parallel would achieve an equivalent pull-up of 2.35k. Am I right ?

[exxos]

Tonight, having started my build, I could have a good look at those resistors, and it's quite tiny, and I feel uneasy to hack them.

On the other hand, we have those marvelous expansion ports, so I was telling myself that leaving alone the existing resistors, and making an extension that add another set of pull-ups resistors (4.7k too) in parallel would achieve an equivalent pull-up of 2.35k. Am I right ?

You could hack up a pull up plug in board for a 68K socket.. I was going to do one, but unless people have problems then it could be left alone anyway...

[kodak80]

I guess this would be why my NetUSBee will not work in the cartridge port?

I have tried in all 3 of my B1 boards and been unable to get the USB port to mount as storage. I also have an Exxos IDE board installed.

[exxos]

I guess this would be why my NetUSBee will not work in the cartridge port?

It could be, but people been moaning about NetUSBee for months, seems it's just inherently buggy.

[kodak80]

I guess this would be why my NetUSBee will not work in the cartridge port?

It could be, but people been moaning about NetUSBee for months, seems it's just inherently buggy.

I had it working on my H4 board, but did note others had issues. If I can find some time, I will see if adding some in-parallel 4.7k pull-ups in an expansion socket changes anything.

[exxos]

I had it working on my H4 board, but did note others had issues. If I can find some time, I will see if adding some in-parallel 4.7k pull-ups in an expansion socket changes anything.

I guess it depends if you fitted 4.7K or 2.2K on the H4 I guess...

[kodak80]

I had it working on my H4 board, but did note others had issues. If I can find some time, I will see if adding some in-parallel 4.7k pull-ups in an expansion socket changes anything.

I guess it depends if you fitted 4.7K or 2.2K on the H4 I guess...

Just checked and, yes, I have 2.2k SIL resistors on my H4 board.

[stephen_usher]

I guess this would be why my NetUSBee will not work in the cartridge port?

NetUSBee is a finicky beast. Just a slight change in the PSU voltage, or the length of the data lines or if there's an 'r' in the month will stop it working.

e.g. on my 520STe it works fine with the stock PSU but can't be seen at all, even to read the Ethernec ROM, with the Exxos PSU. Swap the PSUs over again and it's happy.

[kodak80]

So I have created a board that will fit in an H5 5v expansion socket to allow me to test adding 4.7K pull-ups in parallel. It includes both data and address lines to allow both to be tested.

STF H5 Pull up fix expansion board.png

H5 pull-up fix board schematic.png

H5 Pull-up fix board Eagle BRD.zip