32Mhz OSC fix.

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exxos
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32Mhz OSC fix.

Post by exxos »

This one came about due to this thread viewtopic.php?p=83291#p83291 where the H5 refused to boot up.

I don't know how widespread this problem is. So I am classing this as advisory for the moment. Where you need to place a 470R 0805 resistor as shown below.

IMG_0706.JPG
IMG_0706.JPG (284.56 KiB) Viewed 1334 times

The resistor is a load resistor on the OSC output to GND. The voltage can rise to several volts otherwise, and I think that is whats upsetting the shifter in not giving it a stable clock. If the clock is bad, the system won't even try to boot!

I suspect the problem is more than likely with the new OSC's sold in the store, the YXC branded ones. But it probably won't do any harm in doing this modification as a standard anyway.
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
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alienkidmj12
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Re: 32Mhz OSC fix.

Post by alienkidmj12 »

Sounds similar to something I had but @PhilC fixed it.

All l know is he had to route a wire towards top right of board.

Sorry can't be more helpful,

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Re: 32Mhz OSC fix.

Post by exxos »

@PhilC ??
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
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PhilC
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Re: 32Mhz OSC fix.

Post by PhilC »

exxos wrote: Thu Nov 03, 2022 11:45 am @PhilC ??
It's been a while but I do remember having to fit a few bodge wires, Don't know what to or where though, sorry.
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JezC
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Re: 32Mhz OSC fix.

Post by JezC »

I'm going to try this on my newer H5C1...but any chance of photos of your working board please @alienkidmj12 ?

Just in case it's not just the osc output....

Thanks!
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