H5 A3 & B1 pullup resistor change

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exxos
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H5 A3 & B1 pullup resistor change

Post by 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
Capture.PNG (82.64 KiB) Viewed 4340 times

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...
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
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sporniket
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Re: H5 A3 & B1 pullup resistor change

Post by 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 ?
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Re: H5 A3 & B1 pullup resistor change

Post by exxos »

sporniket wrote: Tue Feb 02, 2021 11:16 pm 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...
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
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Re: H5 A3 & B1 pullup resistor change

Post by 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.
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Re: H5 A3 & B1 pullup resistor change

Post by exxos »

kodak80 wrote: Wed Feb 03, 2021 8:29 am 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.
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Re: H5 A3 & B1 pullup resistor change

Post by kodak80 »

exxos wrote: Wed Feb 03, 2021 8:38 am
kodak80 wrote: Wed Feb 03, 2021 8:29 am 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.
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Re: H5 A3 & B1 pullup resistor change

Post by exxos »

kodak80 wrote: Wed Feb 03, 2021 8:43 am 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...
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Re: H5 A3 & B1 pullup resistor change

Post by kodak80 »

exxos wrote: Wed Feb 03, 2021 8:46 am
kodak80 wrote: Wed Feb 03, 2021 8:43 am 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.
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Re: H5 A3 & B1 pullup resistor change

Post by stephen_usher »

kodak80 wrote: Wed Feb 03, 2021 8:29 am 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.
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Re: H5 A3 & B1 pullup resistor change

Post by 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
STF H5 Pull up fix expansion board.png (18.34 KiB) Viewed 4026 times
H5 pull-up fix board schematic.png
H5 pull-up fix board schematic.png (93.42 KiB) Viewed 4026 times
H5 Pull-up fix board Eagle BRD.zip
(8.14 KiB) Downloaded 160 times
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