RTC Replacement

[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?

IMG_1141.jpg (361.31 KiB) Viewed 8193 times

[exxos]

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.

[Steve]

Also re-check every single trace to the closest vias

[frank.lukas]

Try power the Falcon on and put shortly NVRAM pin18 to GND. When the Falcon boot up set the NVRAM right ...

[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...

[exxos]

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

[avctech]

Also re-check every single trace to the closest vias

Thanks, will try that tomorrow when the light is better

[avctech]

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

Thanks everyone for all your help so far....

[exxos]

Was just checking voltages, and when I checked pin 11 with power on, the Falcon booted, but the keyboard wouldn't work.

Dataline

Capture.JPG (44.96 KiB) Viewed 8130 times

[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

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