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+--- Thread: PC85 Core Board on 1248 Rev I Base board? (/thread-517.html)
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RE: PC85 Core Board on 1248 Rev I Base board? - MbeeTech - 18-06-2022
(18-06-2022, 02:28 PM)CheshireNoir Wrote: A related question: Can I drop the C29 4700uF capacitor on the main board to something smaller? If I change between programs, currently I need to walk away for a few minutes to let that bad boy discharge. Smoothing is good, but this is ridiculous.
John
Hi John.
No need to change the cap, just do a cold reset :
Hold down ESC, press and hold RESET, let RESET go, then let ESC go.
This should clear the ram contents.
RE: PC85 Core Board on 1248 Rev I Base board? - CheshireNoir - 18-06-2022
Cheers Ewan.
I'll use that from now on in.
John
RE: PC85 Core Board on 1248 Rev I Base board? - Ernest - 18-06-2022
(18-06-2022, 05:29 PM)CheshireNoir Wrote: Cheers Ewan.Excellent news John,
I'll use that from now on in.
John
Those red ones can be a pain but mot always.
Sometimes I forget that anyone not cutting their teeth on the Microbee SRAM, wont be familiar with the Hard RESET to clear the RAM.
I just don't think about it, it's just automatic. I think my fingers just know there own way to the combination, I doubt I would be exaggerating much in saying that they have gone through that sequence 100,000 times over the years.
Be aware that the sequence will not allow you to reset in all cases. Some of the games from back in the day disabled normal key function and only some keys would respond. I think it was all in the pursuit rapid response to key input, squeezing ever little bit of SPEED.
If you are running a switch mode power source on this unit , it would probably be a good idea to lower that capacitor anyway. The 4700uF is quite the short circuit at power up to the supply and why stress it more than necessary. a factor of 10 to 470uF @ 25Volt would be fine.
Ernest
RE: PC85 Core Board on 1248 Rev I Base board? - someone - 20-06-2022
(18-06-2022, 08:25 PM)Ernest Wrote: ... The 4700uF is quite the short circuit at power up to the supply...
S100 systems use 68,000 to 110,000uF capacitors on their unregulated +8V line; they're often the size of soft drink cans.
RE: PC85 Core Board on 1248 Rev I Base board? - mjelic - 26-06-2022
(18-06-2022, 02:28 PM)CheshireNoir Wrote: Smoothing is good, but this is ridiculous.LOL! Right?! I've never seen anything like it.
RE: PC85 Core Board on 1248 Rev I Base board? - ChickenMan - 28-07-2022
The System 80 power supply uses an axial 22,000uF, eventually found a replacement from Mouser, should be here by the end of the week
RE: PC85 Core Board on 1248 Rev I Base board? - CheshireNoir - 28-07-2022
All I can say is "Don't lick the spicy end".
John
RE: PC85 Core Board on 1248 Rev I Base board? - someone - 29-07-2022
(28-07-2022, 12:45 PM)CheshireNoir Wrote: All I can say is "Don't lick the spicy end".
John
Before or after it has exploded?