RTC Replacement

Current solutions and designs.
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avctech
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RTC Replacement

Post by avctech »

I replaced the RTC today. Desoldering the old one was not as simple as expected because it had a plastic cover which meant I couldn't snip the legs first.

Anyway, desoldered the old one (quite easily), cleaned up the pads and soldered in the new one, easy....or so I thought.

Connected the PSU, RAM floppy and keyboard and the Falcon won't boot. I get the power light and the fan (which I also replaced) spins away happily to itself, but the floppy won't boot and I get no video output.

I have tried the ALT+SHIFT+RSHIFT+UNDO but that doesn't help.

The RTC is getting 5v and the ground is connected, the battery is showing 3.1v

Any suggestions before I decide it's now a retro doorstop? :lol:
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exxos
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Re: RTC Replacement

Post by exxos »

avctech wrote: Fri Aug 21, 2020 2:23 pm I have tried the ALT+SHIFT+RSHIFT+UNDO but that doesn't help.
Are you holding down all these keys and then turning on the power ? It is pretty difficult to do without a second pair of hands.

Also what is the floppy light doing, normally It will flash several times fast, then be off for a couple of seconds, then flash very fast again.. Meaning the RTC is unable to basically initialise.
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Steve
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Re: RTC Replacement

Post by Steve »

Also re-check every single trace to the closest vias
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frank.lukas
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Re: RTC Replacement

Post by frank.lukas »

Try power the Falcon on and put shortly NVRAM pin18 to GND. When the Falcon boot up set the NVRAM right ...
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avctech
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Re: RTC Replacement

Post by avctech »

Are you holding down all these keys and then turning on the power ? It is pretty difficult to do without a second pair of hands.
Tried with a little helper, but still no joy.
Also what is the floppy light doing, normally It will flash several times fast, then be off for a couple of seconds, then flash very fast again.. Meaning the RTC is unable to basically initialise.
Yep, that is what it is doing...
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Re: RTC Replacement

Post by exxos »

avctech wrote: Fri Aug 21, 2020 8:12 pm Yep, that is what it is doing...
Sounds like the RTC is failing to initialise, so I would check the traces to it as I assume you have a bad data line or something, Falcon circuit diagram is on here...https://www.exxosforum.co.uk/forum/viewt ... f=31&t=100
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avctech
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Re: RTC Replacement

Post by avctech »

Steve wrote: Fri Aug 21, 2020 3:45 pm Also re-check every single trace to the closest vias
Thanks, will try that tomorrow when the light is better :D
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avctech
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Re: RTC Replacement

Post by avctech »

exxos wrote: Fri Aug 21, 2020 8:37 pm
avctech wrote: Fri Aug 21, 2020 8:12 pm Yep, that is what it is doing...
Sounds like the RTC is failing to initialise, so I would check the traces to it as I assume you have a bad data line or something, Falcon circuit diagram is on here...https://www.exxosforum.co.uk/forum/viewt ... f=31&t=100
Was just checking voltages, and when I checked pin 11 with power on, the Falcon booted, but the keyboard wouldn't work.

Rebooting, I have the same problem, no video output and flashing floppy light.

Will check the traces tomorrow when the light is better, it does sound like one of my solder joints could be iffy :D

Thanks everyone for all your help so far....
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Re: RTC Replacement

Post by exxos »

avctech wrote: Fri Aug 21, 2020 8:49 pm Was just checking voltages, and when I checked pin 11 with power on, the Falcon booted, but the keyboard wouldn't work.
Dataline :)

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https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
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avctech
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Re: RTC Replacement

Post by avctech »

At least I now know I didn't break anything, that was my big worry. Been soldering for years, but my micro electronics is a bit rusty after 20 years, so had that doubt in my mind :shock:

Will check everything again tomorrow, now I am on the right track (pardon the pun) :lol:
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