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Electronics => Repair => Topic started by: sampler1 on August 18, 2022, 11:54:25 pm

Title: Synthesizer main board. XP-80 CPU?
Post by: sampler1 on August 18, 2022, 11:54:25 pm

Hi All something a bit different.
Im working on a synthesizer Roland XP-80 that won't boot. I replaced all the SMD Caps as many were leaking But it's still not booting. I am wondering if someone can shed some light for me . I checked the clock on the CPU ( IC12)  HD6437034 and that seems ok. I then checked the Reset and its high. From what I read if its high the CPU should reset.
I have never checked RESET. Can someone clarify ? I think if the Reset was low the cpu would function.
https://www.synthxl.com/roland-xp-80/ (https://www.synthxl.com/roland-xp-80/)
Any help would be great!
Regards

Title: Re: Synthesizer main board. XP-80 CPU?
Post by: wasedadoc on August 19, 2022, 12:46:48 am

No, the reset pin is active low.  See the HD6437034 datasheet.  Low resets the CPU. High lets it run.

Page 11 of https://docs.rs-online.com/4ca5/0900766b80c2b5e5.pdf

Title: Re: Synthesizer main board. XP-80 CPU?
Post by: sampler1 on August 19, 2022, 03:09:47 am

Thank you !
So if I get this my clock is working and the CPU is running. Time to move on to something else.
Now the question is . ???
All the rails are ok, all the caps are changed, CPU is ok. Hummmm

Big thanks !